Journal articles: 'Primary sedimentation tank'

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Li, Ya Feng, Xin Wang, and Sha Liu. "Engineering Example of A²O-High Density Sedimentation Tank-Filter Tank Process in the Treatment of Municipal Sewage." Applied Mechanics and Materials 178-181 (May 2012): 671–75. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.671.

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The process parameters and running effect of A2O-high density sedimentation tank-filter tank process applied in the treatment of municipal sewage were introduced，aiming to provide technical basis for broad application of A2O-high density sedimentation tank-filter tank process. An engineering case was taken as example to describe process flow, process parameters and the size of the structures. The character of the designing was explained along with the discussion of the running effect. The running effort shows that municipal sewage treated by A2O-high density sedimentation tank-filter tank process can meet the requirements of Grand A of Primary standard of Discharge standard of pollutants for municipal wastewater treatment plant（GB189118—2002）.

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Lindeborg, Claës, Niklas Wiberg, and Alexander Seyf. "Studies of the dynamic behaviour of a primary sedimentation tank." Water Science and Technology 34, no. 3-4 (August 1, 1996): 213–22. http://dx.doi.org/10.2166/wst.1996.0435.

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This study concerns the dynamic behaviour of a primary sedimentation tank in a municipal WWTP. It is a part of the effort to estimate the varying biological load on the activated sludge stage under different operating conditions. The primary settlers have been investigated with several methods: (i) cross sectional sampling of suspended solids; (ii) tracer tests with lithium-solution; (iii) finite element method (FEM); (iv) flow measurement with a turbine-type sensor; and (v) cross-sectional flow measurement with a cross-bar metering device. The choice of measurement positions, the number of samples and the methods selected for analyses have all been guided by the ambition to avoid erroneous conclusions due to odd single measurement data. The study demonstrates how modern graphical computer methods like Finite Element Method and MATLAB Toolboxes can be used to increase our understanding of the settler.

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Shahrokhi, Mahdi, Fatemeh Rostami, Md Azlin Md Said, Saeid-Reza Sabbagh-Yazdi, Syafalni Syafalni, and Rozi Abdullah. "The effect of baffle angle on primary sedimentation tank efficiency." Canadian Journal of Civil Engineering 39, no. 3 (March 2012): 293–303. http://dx.doi.org/10.1139/l2012-002.

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Li, Yuan, Jie Liu, Yibiao Yu, Hao Zhu, Zheng Shen, and Yalei Zhang. "Particle Size Distribution Based Occurrence Features of Organic Components in Printing and Dyeing Wastewater Under a Treatment Process." E3S Web of Conferences 118 (2019): 04009. http://dx.doi.org/10.1051/e3sconf/201911804009.

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A more detailed occurrence features of organic matters in the printing and dyeing wastewater, based on its particle size distribution (PSD) and along with a wastewater treatment process, was conducted to provide a support for advanced treatment. Results suggested that, (1) In the dyeing wastewater, the occurrence characteristic of COD was: soluble>supra colloidal>colloidal>settleable; However, for protein, the supra colloidal was dominant, followed by the soluble. The feature of the polysaccharide was consistent with COD’s. In the wastewater, 29.66% of COD could be attributed to proteins and 3.45% of the COD could be attributed to polysaccharides. (2) The relationship among the forms of COD in the primary sedimentation tank, aerobic tank, secondary sedimentation tank, and reverse osmosis-treated concentrated effluent was consistent, that was: soluble>colloidal>supra colloidal>settleable. (3) In the primary sedimentation tank, the settleable COD was almost completely removed; In the aerobic tank, the residual super colloidal COD was not much; After MBR-RO treatment, the COD in the reverse osmosis concentrated water was almost dissolved and only a little presented in other forms.

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Gaastra, S. B., P. P. Weesendorp, J. Zabicki, and J. W. van Dijk. "Practical Experiments with Chemical Pre-Treatment in a Primary Sedimentation Tank." Water Science and Technology 24, no. 10 (November 1, 1991): 337–38. http://dx.doi.org/10.2166/wst.1991.0324.

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Gamal El-Din, A., and D. W. Smith. "Modeling a Full-Scale Primary Sedimentation Tank Using Artificial Neural Networks." Environmental Technology 23, no. 5 (May 2002): 479–96. http://dx.doi.org/10.1080/09593332308618384.

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Du, Shu Xin, Yuan Qing Wu, and Zhi Bao Yuan. "Detection of COD in the Wastewater Treatment Process Based on Fluorescence Excitation-Emission Matrix Spectrometry." Applied Mechanics and Materials 178-181 (May 2012): 599–602. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.599.

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In the wastewater treatment process, it is necessary to detect the concentrations of organic matter in order to monitor the operation and adjust the process parameters. Based on fluorescence excitation-emission matrix spectrometry, Chemical oxygen demand (COD) of effluent wastewater in the primary sedimentation tank, the secondary sedimentation tank and the final sedimentation tank of Hengdian Wastewater Treatment Plant, Zhejiang Province, is detected respectively based on fluorescence excitation-emission matrix spectrometry. In order to compare the modeling performance, principal component regression (PCR), partial least squares (PLS), parallel factor analysis (PARAFAC) and multi-way partial least squares (N-PLS) are respectively used to build the calibration models between the fluorescence spectrometry and COD. Experimental results show PLS is better than PARAFAC and N-PLS in the aspect of modeling performance for detecting COD in the wastewater.

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Apri Yulianto, Arlini Radityaningrum, and Ro’du Dhuha Afrianisa. "Rancang Bangun Biofilter untuk Pengolahan Limbah Cair Kegiatan Sentra Wisata Kuliner di Kecamatan Tambaksari, Kota Surabaya." Al-Ard: Jurnal Teknik Lingkungan 6, no. 2 (May 18, 2021): 86–95. http://dx.doi.org/10.29080/alard.v6i2.1175.

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The development of culinary business at Culinary Tourism Centre (CTC) has produced domestic wastewater from dish washing activities and food residues. One CTC in Tambaksari District, Surabaya City has not had Wastewater Treatment Plant (WWTP) yet. The CTC only has equalization tank for accommodating wastewater before discharged into the water body. This research aimed to determine the characteristics of domestic wastewater from the CTC and to design the appropriate WWTP in the CTC. The standard was based on the Regulation of the East Java Governor Number 72 Year 2013. The result showed that the concentrations of TSS, grease and oil, BOD, COD were 14 mg/L, 1.59 mg/L, 1154.8 mg/L, and 2054.8 mg/L, respectively. The WWTP units consisted of a grease trap, an equalization tank, primary sedimentation tank, anaerobic tank, aerobic tank, and secondary sedimentation tank. The estimated cost to build the WWTP was IDR 278,093,774.

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Ruider, E., H. Kroiss, and W. von der Emde. "Experience with a Selector Used for Treatment of Sugar Beet Waste." Water Science and Technology 20, no. 4-5 (April 1, 1988): 9–21. http://dx.doi.org/10.2166/wst.1988.0150.

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The largest sugar mill in Austria is situated on a small creek (100-200 1/s) and the waste water, which has a flow of up to 45000 m3/d, is treated in a low loaded activated sludge plant with a selector. The installed plant consists of a 6700 m3 capacity primary sedimentation tank, a 400 m3 selector (coarse bubble aeration tank), a main aeration tank of 16000 m3 capacity equipped with 16 mammoth rotors each 9 m long and a final settling tank. The plant has operated very reliably since it started to run in the campaign of 1984.

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Dupont, René, and Claus Dahl. "A one-dimensional model for a secondary settling tank including density current and short-circuiting." Water Science and Technology 31, no. 2 (January 1, 1995): 215–24. http://dx.doi.org/10.2166/wst.1995.0105.

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This paper presents a dynamic one-dimensional flux model for the secondary settling tank which is suitable for use with the latest innovations in models for activated sludge tanks, and which takes into account observed effects of density current and short-circuiting. The components of the influent to the settling tank are divided into three fractions. Soluble components, non-settleable particulate components (primary particles), and settleable particulate components. (macroflocs). Soluble components and primary particles are considered to follow the hydraulic flow in the settling tank. The transport of macroflocs in the settling tank is modelled according to the traditional flux theory on a layer model of the settling tank extended with a model for density current and short-circuiting. For modelling of the density current in the inlet region of the settler a dynamic inlet height is introduced. The short-circuiting is modelled by the introduction of a factor which accounts for the dilution in the suspended solids concentration at the bottom of the settling tank down to the concentration in the return sludge flow. Settling velocities of the macroflocs for both free and hindered sedimentation are measured, and a new model for the settling velocity is proposed. The model is validated with data from the wastewater treatment plant Lynetten, Copenhagen, Denmark. It was found that the suspended sludge concentration profile and the suspended sludge concentration in the return sludge were predicted well with the model.

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Shi, Xuan, Yi Yao, Nan Zhao, Xin Jin, Pengkang Jin, Xiaochang Wang, and Guanghua Wang. "Characteristics of flow regime adjustment enhancing carbon source recovery in activated primary sedimentation tank." Chemosphere 251 (July 2020): 126405. http://dx.doi.org/10.1016/j.chemosphere.2020.126405.

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Zeghal, Slim, Nelu Puznava, Jean Philippe Subra, and Patrick Sauvegrain. "Process control for nutrients removal using lamella sedimentation and floating media filtration." Water Science and Technology 38, no. 3 (August 1, 1998): 227–35. http://dx.doi.org/10.2166/wst.1998.0214.

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The objective of this work is to provide an efficient method to control the dosing of chemicals in order to optimise the operation of the complete treatment train associating phosphorus precipitation in a lamellae separator followed by nitrogen removal in a Biostyr® filter with methanol addition. Four coagulation-flocculation tanks of 1.54 m3 total volume were used, followed by a lamellae primary tank of 0.65 m2 footprint and 5.4 m2 total settling surface. On-line measurements were used. The pilot was operated initially with no chemicals, at constant and variable flow. Different control strategies were sought. To help tune the controllers, step changes in chemicals dosing were made to identify the open-loop process transfer function at different flow rates. The system was then operated in closed loop. This proved to be an efficient means of operating the system. Future work will continue to test various control strategies.

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Mazzolani, G., F. Pirozzi, and G. d'Antonoi. "A generalized settling approach in the numerical modeling of sedimentation tanks." Water Science and Technology 38, no. 3 (August 1, 1998): 95–102. http://dx.doi.org/10.2166/wst.1998.0184.

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Numerical models for the prediction of turbulent flow field and suspended solid distribution in sedimentation tanks are characterized by refined modeling of hydrodynamics, but apparently weak modeling of settling properties of suspensions. It is known that sedimentation tanks typically treat highly heterodisperse suspensions, whose concentrations range from relatively high to low values. However, settling is modeled either by considering one or more particle classes of different settling velocity, without accounting for hindered settling conditions, or by treating the suspension as monodisperse, even in regions of low concentration. A new generalized settling model is proposed to account for both discrete settling conditions in low concentration regions of the tanks and hindered settling conditions in high concentration regions. Settling velocities of heterodisperse suspensions are then determined as a function of particle velocities in isolation and their total concentration. The settling model is used in the framework of a transport model for the simulation of hydrodynamics and solid distribution in a rectangular sedimentation tank. Results show that solid distribution is mainly affected by particle interactions in the inlet region and by settling properties of individual particles in the outlet region. Comparison of the proposed settling model with other settling models suggests that a generalized approach of the modeling of settling properties of suspensions is a primary concern to obtain reliable predictions of the removal rate.

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Mwamila, Tulinave Burton, Moo Young Han, and Soyoon Kum. "Sustainability evaluation of a primary school rainwater demonstration project in Tanzania." Journal of Water, Sanitation and Hygiene for Development 6, no. 3 (July 8, 2016): 447–55. http://dx.doi.org/10.2166/washdev.2016.186.

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Water shortages are widely prevalent in developing countries, affecting lives of people including schoolchildren, who miss classes while fetching water for daily use. A typical case was that of Mnyundo Primary School in Tanzania, East Africa. A rainwater harvesting (RWH) system was then constructed because of easy adaptability of the technology. The purpose of this study is sustainability evaluation. The evaluation considered construction details, level of water supply service, potential for sustainability and replication. Coarse screen, first flush tank, and sedimentation tank were included for maintaining drinkable water quality through particle load reduction. The water level gauge incorporated enables easy monitoring of water usage, while the provided training and operational manual are a practical guide on system management for the users. Local labor, material and techniques used, are recommended for capacity building, sense of ownership, and cost reduction. Companies’ involvement is encouraged by providing financial support to the schools as their corporate social responsibility. RWH is thus suggested as a sustainable alternative for drinking water supply.

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Hatziconstantinou, G. J., P. Yannakopoulos, and A. Andreadakis. "Primary sludge hydrolysis for biological nutrient removal." Water Science and Technology 34, no. 1-2 (July 1, 1996): 417–23. http://dx.doi.org/10.2166/wst.1996.0399.

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Primary sludge hydrolysis can enrich primary effluent with the soluble organics which in turn can be a valuable carbon source to subsequent nutrient removal processes. By controlling hydraulic retention time and temperature it is possible to confine the anaerobic digestion of the primary sludge to the acidogenic and acetogenic phase (hydrolysis/fermentation process), and take advantage of the soluble organics produced. This paper presents the results of a research involving bench and pilot scale experiments related to primary sludge hydrolysis. The pilot scale sedimentation tank (4.10 m in diameter, 3.20 m in depth) operated over an expended period of 21 months as a conventional clarifier and following this as a fermentor unit employing sludge recirculation. Parallel to the pilot scale experiments, several batch and continuous flow bench scale experiments were conducted in order to determine the factors controlling the production of soluble organics and the effect of the latter on the denitrification process. The conclusions drawn were that a) a soluble COD production of the order of 5-6% in terms of sludge TCOD can be expected in a batch fermentor operating with HRT≅2days at T≤ 20°C, b) in a continuous flow fermentor, combinations of T>20°C and SRT>2 should be applied in order to achieve a production of the order of 10%, c) significant soluble carbon production can be achieved in primary sedimentation tanks (over 30% in terms of influent SCOD) when relatively increased SRTs (4 to 5 days) in combination with sludge recirculation are employed, under T>22°C, and d) increased denitrification performance of the order of 9 mgNOx/g MLSS.hr, can be achieved with hydrolysate as a carbon source.

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Li, Yuhao, Bruce R. Sutherland, Murray K. Gingras, George W. Owttrim, and Kurt O. Konhauser. "A novel approach to investigate the deposition of (bio)chemical sediments: The sedimentation velocity of cyanobacteria–ferrihydrite aggregates." Journal of Sedimentary Research 91, no. 4 (April 22, 2021): 390–98. http://dx.doi.org/10.2110/jsr.2020.114.

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ABSTRACT Sedimentation velocities of various chemical sediments are typically calculated using Stokes's law. However, applying it to chemical sediments that form in situ in the water column is not ideal because the particle properties do not fulfill many of the assumptions underpinning the applicability of Stokes' law. As a consequence, it has been difficult to predict the sedimentation rate of ancient chemical sediments, such as Precambrian banded iron formations (BIF), because their primary sediments likely comprised aggregates of ferric hydroxides, such as ferrihydrite [Fe(OH)3], and marine bacterial biomass, including cyanobacteria. In this work we use a new experimental method to address the mechanisms by which primary BIF sediment, formed by the oxidation of dissolved Fe(II) by O2 and simultaneously incubated with cyanobacterium Synechococcus sp., were deposited to the Archean ocean. Specifically, we formed the aggregates in situ over a wide range of initial pH and Fe(II) concentrations, continuously recorded the entire settling processes of aggregates under each condition, and then processed the data in MATLAB according to different settling mechanisms. Our results demonstrate that ferrihydrite–cyanobacteria aggregates settled to the ocean floor either through the formation of uniformly descending concentration fronts or through convective plumes. The sedimentation mechanism depended on both initial Fe(II) concentration and the pH. Correspondingly, two algorithms were developed to characterize the sedimentation velocity. These algorithms tracked the alteration of light intensity from low to high as sediments descended from an initially homogeneous state through a water tank, and as well calculated the average light intensity over time, from which vertical time series were constructed allowing calculation of the sedimentation velocity. Our method not only provides an accurate estimation of the in situ sedimentation velocity of cell–mineral aggregates, but also provides new insights into the physical mechanisms by which the primary sediments composing BIF were deposited.

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Trzcinski, Antoine Prandota, Chong Wang, Dongqing Zhang, Wui Seng Ang, Li Leonard Lin, Terutake Niwa, Yasuhiro Fukuzaki, and Wun Jern Ng. "Performance of A-stage process treating combined municipal-industrial wastewater." Water Science and Technology 75, no. 1 (October 31, 2016): 228–38. http://dx.doi.org/10.2166/wst.2016.511.

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A biosorption column and a settling tank were operated for 6 months with combined municipal and industrial wastewaters (1 m3/hr) to study the effect of dissolved oxygen (DO) levels and Fe3+ dosage on removal efficiency of dissolved and suspended organics prior to biological treatment. High DO (>0.4 mg/L) were found to be detrimental for soluble chemical oxygen demand (COD) removals and iron dosing (up to 20 ppm) did not improve the overall performance. The system performed significantly better at high loading rate (>20 kg COD.m−3.d−1) where suspended solids and COD removals were greater than 80% and 60%, respectively. This is a significant improvement compared to the conventional primary sedimentation tank, and the process is a promising alternative for the pre-treatment of industrial wastewater.

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El-Din, Ahmed Gamal, and Daniel W. Smith. "A combined transfer-function noise model to predict the dynamic behavior of a full-scale primary sedimentation tank." Water Research 36, no. 15 (September 2002): 3747–64. http://dx.doi.org/10.1016/s0043-1354(02)00089-1.

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Hien, P. G., L. T. K. Oanh, N. T. Viet, and G. Lettinga. "Closed wastewater system in the tapioca industry in vietnam." Water Science and Technology 39, no. 5 (March 1, 1999): 89–96. http://dx.doi.org/10.2166/wst.1999.0226.

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Wastewater from tapioca processing factory containing high COD (11,077-19,083 mg/l), SS (4,180-7,600 mg/l) and low pH (4.33-5.60) still causes heavy pollution to receiving water in South Vietnam. Closing the water circuit in the tapioca industries represents a very attractive option for eliminating pollution problems and the reuse of treated wastewater and solid wastes. The investigated and presently occasionally already implemented system consists of primary sedimentation tank, anaerobic treatment using UASB-reactors, aeration tanks using attached growth reactor and oxidation ponds system. Under laboratory conditions, organic loading rates applied in UASB-reactors are up to 40,35 kg COD/m3.d with treatment efficiency of 90-95%, reducing the COD concentration from up to 13,449 mg/l to 624-780 mg/l. The final effluent COD (sol.) after treatment in the pond system operated at hydraulic retention time of 12-20 days is lower than 10 mg/l. This effluent is suited very well either for use in agriculture or in the factory.

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Yu, Y. H., and K. S. L. Lo. "A Pilot-Plant Study to Salvage a Full-Scale Treatment Plant." Water Science and Technology 25, no. 1 (January 1, 1992): 93–98. http://dx.doi.org/10.2166/wst.1992.0014.

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Kwei-Shan Wastewater Treatment Plant is the second oldest treatment plant ever designed and operated in Taiwan, to treat the combined industrial wastewater collected from various kinds of factories located in Kwei-Shan Industrial Park. From the beginning the treatment plant has been suffering from influents containing a spectrum of various pollutants harmful to the activated-sludge system of the plant. Extreme pH measurements (1.4-12.0), jumpy organic contents (COD 104-6660 mg/l), high metal concentrations (Cu up to 19 mg/l, Zn up to 37 mg/l), and high grease concentrations (up to 470 mg/l) were unbelievably found in tne plant influents, while a traditional plain primary settling tank was the only shield to protect the aeration basin from damage. In a dilemma like this, a pilot-plant study was undertaken to save the efficiency of the existing biological treatment plant from those various fatal influent constituents. A flow equalization tank and a chemical treatment unit were first built to damp out pH and COD variations, Ca(OH)2 was added to remove the toxic metals as well as part of the grease. The effluent after the above treatment was then neutralized and sent to the downscaled activated sludge system containing one aeration tank and one settling tank. The results indicated that equalization and chemical precipitation by using the existing space of the roughing filter and the sedimentation tank could produce much safer influents to the activated sludge system.

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He, Li, Tao Tan, Zhixi Gao, and Leilei Fan. "The Shock Effect of Inorganic Suspended Solids in Surface Runoff on Wastewater Treatment Plant Performance." International Journal of Environmental Research and Public Health 16, no. 3 (February 4, 2019): 453. http://dx.doi.org/10.3390/ijerph16030453.

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Previous studies on the water quality of surface runoff often focused on the chemical oxygen demand (COD), nitrogen, phosphorus, and total suspended solid (TSS), but little is known in terms of the inorganic suspended solids (ISS). This research investigated the effects of ISS carried by surface runoff on the treatment efficiency of the pretreatment facilities and the ratio of mixed liquor volatile suspended solid to mixed liquor suspended solid (MLVSS/MLSS) of the activated sludge in a wastewater treatment plant (WWTP) with the anaerobic-anoxic-oxic (AAO) process in Chongqing city, China. The results showed that the surface runoff had a long-lasting impact on the grit removal capacity of the grit chamber, affecting the normal operation after the rainfall. In contrast, the primary sedimentation tank showed strong impact resistance with higher removal rates of COD, TSS, and ISS. Nonetheless, the primary settling tank aggravates the removal of organic carbon in sewage during rainfall, having a negative impact on subsequent biological treatment. The ISS in the surface runoff could increase the sludge concentration and decrease the MLVSS/MLSS ratio. After repeated surface runoff impact, the MLVSS/MLSS ratio in the activated sludge would drop below even 0.3, interrupting the normal operation of WWTP.

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Bhatia, Nikhil, and Lalsangzela Sailo. "Optimal Design for Conventional Wastewater Treatment Systems using a Computing Language MATLAB R2012a." Science & Technology Journal 5, no. 1 (January 1, 2017): 16–21. http://dx.doi.org/10.22232/stj.2017.05.01.02.

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In the present scenario of rapid urbanization, the demand for wastewater treatment is continuously increasing. The majority of research in the field of wastewater treatment plant (WWTP) is focusing on its modeling part. The design of WWTP is developed using professional quality software packages which incorporate the fundamental concepts with the key engineering principles. With the aim to obtain an optimal design, in this study a novel Decision Support System (DSS) is developed for the preliminary units integrating screening chamber, grit chamber and equalization tank with primary sedimentation tank as the primary process and activated sludge process, trickling filter and rotating biological contactor as different types of the secondary units of Wastewater Treatment System using a computing language MATLAB R2012a. DSS is a comprehensive and user-friendly program which could incorporate most of the theoretical and practical constraints. One of the major concerns of DSS is the dimension constraint for the design and operation of WWTP. DSS incorporates miscellaneous mathematical functions and the code to develop a user-desired design. The applicability of the DSS model is illustrated through the various design problems. The design developed will support the future growth and development of the cost optimization models for WWTP.

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MONAGHAN, JOE J., CATHERINE MÉRIEUX, HERBERT E. HUPPERT, and JOHN MANSOUR. "Particulate gravity currents along V-shaped valleys." Journal of Fluid Mechanics 631 (July 17, 2009): 419–40. http://dx.doi.org/10.1017/s0022112009007174.

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This paper extends previous studies of saline gravity currents at high Reynolds number flowing along a tank with a V-shaped valley. We use experiments and a box model to determine the primary features of the flow. The particulate gravity currents were initiated by releasing a fixed volume of fluid consisting of pure water mixed with silicon carbide particles from a lock at one end of the tank. The resulting motion and deposit pattern differ significantly from those for the propagation of a particulate gravity current along a flat-bottomed tank. The front of the current, seen from above, is approximately parabolic (with axis parallel to the flow direction) in contrast to the current in a flat-bottomed tank where it is nearly a straight line perpendicular to the flow. This feature mimics the results for pure saline currents. When seen in profile the currents do not have a clearly defined raised head, which is a feature of the flat-bottomed currents. The mass deposited per unit area varies nearly monotonically with respect to distance down the tank, again in contrast to the case of the flat-bottomed tank. The exceptions to this are the two experiments which have the highest ratio of lock height to length. The mass deposited per unit area across the V-shaped valley is much larger in the central part of the valley than it is on the flanks for any position along the valley. We find that the results can be described with remarkable accuracy by a box model using a generalization of the equation for sedimentation from a turbulent medium due to Martin and Nokes. Our results further show that the factor used in the deposition rate equation which is commonly assumed to be 1 should be smaller, typically 0.7.

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Nakada, N., M. Yasojima, Y. Okayasu, K. Komori, and Y. Suzuki. "Mass balance analysis of triclosan, diethyltoluamide, crotamiton and carbamazepine in sewage treatment plants." Water Science and Technology 61, no. 7 (April 1, 2010): 1739–47. http://dx.doi.org/10.2166/wst.2010.100.

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The behavior of antibacterial triclosan, insect-repellent diethyltoluamide (DEET), anticonvulsant carbamazepine, and antipruritic crotamiton was investigated at two sewage treatment plants (STPs) to clarify their complete mass balance. Twenty-four-hour flow-proportional composite samples were collected from the influent and effluent of primary and final sedimentation tanks, a biofiltration tank and disinfection tanks. Sludge samples (i.e., activated and excess sludge) and samples of the return flow from the sludge treatment process were collected in the same manner. The analytes in both the dissolved and particulate phases were individually determined by a gas chromatograph equipped with mass spectrometer. Triclosan was dominantly detected in the particulate phase especially in the early stage of treatment (up to 83%) and was efficiently removed (over 90%) in STPs, mainly by sorption to sewage sludge. Limited removal was observed for DEET (55±24%), while no significant removal was demonstrated for crotamiton or carbamazepine. The solid-water distribution coefficients (Kd, n=4) for triclosan (log Kd: 3.7–5.1), DEET (1.3–1.9) and crotamiton (1.1–1.6) in the sludge samples are also determined in this study. These findings indicate the limitations of current sewage treatment techniques for the removal of these water-soluble drugs (i.e. DEET, carbamazepine, and crotamiton).

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Nakada, N., M. Yasojima, Y. Okayasu, K. Komori, H. Tanaka, and Y. Suzuki. "Fate of oestrogenic compounds and identification of oestrogenicity in a wastewater treatment process." Water Science and Technology 53, no. 11 (May 1, 2006): 51–63. http://dx.doi.org/10.2166/wst.2006.337.

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Understanding of the fate of oestrogen and oestrogenic compounds is important in improving the removal efficiency for oestrogens in wastewater treatment plants (WWTPs). In this study an attempt was made to clarify the fate of oestrogen, oestrogen sulphates, and oestrogenic compounds (synthetic oestrogen, nonylphenol and its relatives) by an instrumental analysis, and the fate of oestrogenicity by an in vitro assay. The investigation was conducted in an activated sludge WWTP in winter and summer, focusing on identification of the primary substances that induce oestrogenicity. Wastewater samples were analysed by employing the silica-gel fractionation technique in conjunction with two-step column chromatography. The results revealed that, in winter, the WWTP efficiencies for the removal of nitrogen and oestrogens decreased and the oestrone level increased with the progress of the treatment. Oestrone and oestrogenic substances are likely to circulate between the aeration tank and the final sedimentation tank. In summer, however, these compounds were effectively removed in the WWTP. The results of the column chromatography coupled with the bioassay suggested that E1 and E2 are the predominant contributors to the oestrogenicity in the influent, return sludge and effluent of the WWTP. The measurement by the instrumental analysis supported these findings.

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Fleckseder, H., L. Prendl, and H. Meulenbroek. "The Staging of Large Wastewater Treatment Plants - A “Modular” Approach." Water Science and Technology 25, no. 4-5 (February 1, 1992): 67–73. http://dx.doi.org/10.2166/wst.1992.0482.

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The primary driving force for re-investments in wastewater treatment plants in Austria - and also other countries in Central Europe - is at present not an increase in load to treatment but a marked increase in effluent requirements to be fulfilled. (The re-investments necessary for sludge handling and treatment remain outside this paper.) Within a period of 20 years, the load specific requirements on aeration tank volume rose five- to tenfold, when Lv = 2.0 kg BOD5/(m3d) was the starting value, and roughly doubled for final clarifiers. In addition, the importance of the application and expansion of primary sedimentation decreased as well. This development over time in Central European countries as well as the need to utilize previous investments as long as possible - 35 to 60 years for civil works are common as periods of depreciation - indicate that investments in new plant at any location in the world have to consider the possible whole life cycle of a plant and that plant hydraulics becomes the “key hook” for expandability.

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Inagaki, Tetsuya, Yukari Shinoda, Mitsuhiro Miyazawa, Hitoshi Takamura, and Satoru Tsuchikawa. "Near-infrared spectroscopic assessment of contamination level of sewage." Water Science and Technology 61, no. 8 (April 1, 2010): 1957–63. http://dx.doi.org/10.2166/wst.2010.070.

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We examined the use of near infrared (NIR) spectroscopy as a rapid technique for the evaluation of sewage quality. Influent water samples, primary sedimentation tank water samples, and final effluent water samples were collected from sewage treatment facilities in Nagoya, Japan and their NIR spectra obtained. Partial least squares (PLS) models for total phosphate (TP), total nitrogen (TN), biochemical oxygen demand (BOD), total organic carbon (TOC), and turbidity of sewage water were constructed from the NIR data. The models provided good correlation between measurements obtained conventionally and those predicted from spectroscopy. Spectral variation induced by background interference in samples affected accuracy. Loading plots and score plots derived from PLS regression analysis resolved the background interference and allowed highly accurate predictions. Spectral variation induced by contamination in the sewage was a main predictor of sewage quality. These results show that NIR spectroscopy shows potential for in-line, non-destructive measurement of sewage quality.

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Lessard, P., D. Martel, and B. Desjardins. "Modélisation du comportement des matières en suspension à l'effluent d'un décanteur primaire lamellaire." Canadian Journal of Civil Engineering 20, no. 5 (October 1, 1993): 767–77. http://dx.doi.org/10.1139/l93-102.

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Process modelling can prove a useful tool for the control of wastewater treatment plants. The objective of this research was to verify that a primary settling model developped for a conventional process is applicable to a process using lamellar settling. The lumped-parameter model examines the hydraulics of a system composed of stirred tank reactors in series and simulates suspended solid concentration of the effluent under various flow regimes. The model has been validated using data collected from a pilot lamella settler of a capacity of 15 m3 and operated over a wide range of flows (Hazen velocity between 0,43 and 2,59 m∙h−1). The prediction of the model was in agreement with the observed values both in terms of concentration and hydraulic behavior of effluent suspended solids (average relative error of 17%). How ever, less satisfactory was the model performance tested with the concentration data on settleable solids. Research is under way to study the different mechanisms of sedimentation going on in the settler. Key words: modelling, lamellar settling, settleable suspended solids.

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Ali, Arshad, and Muhammad Jawed Iqbal. "Proposed Wastewater Treatment Plant for a Paper Mill." Hydro Nepal: Journal of Water, Energy and Environment 11 (July 7, 2012): 25–28. http://dx.doi.org/10.3126/hn.v11i0.7157.

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The decline in the availability and alarming pollution of the existing water resources is the major environmental problem of third-world countries. The main reason of water pollution is the disposal of untreated industrial effl uents. This study was designed to evaluate the pollution load caused by a paper mill, and to propose a wastewater treatment plant design, based on the analyses of wastewater samples. The wastewater samples were collected from the local paper mill for a period of more than four months on a regular basis. The pH, temperature, color, TSS, TDS, BOD, COD and AOX were measured as, 8.1, 23°C, 2,431 PtCo unit, 956 mg/L, 3,046 mg/L, 1,582 mg/L, 2,492 mg/L and 19.81 mg/L, respectively. Based on the data obtained, the wastewater treatment plant consisting of a screening chamber, primary sedimentation tank and a UASB reactor was designed. It was concluded that the treatment effi ciency of more than 75% removal of BOD and COD concentrations could be accomplished. The treatment plant will also be able to produce 2,200 m3/day of biogas.DOI: http://dx.doi.org/10.3126/hn.v11i0.7157 Hydro Nepal Vol.11 2011 pp.25-28

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Zdybel, Jolanta, Tomasz Cencek, Jacek Karamon, and Teresa Kłapeć. "Effectiveness of Selected Stages of Wastewater Treatment in Elimination of Eggs of Intestinal Parasites." Bulletin of the Veterinary Institute in Pulawy 59, no. 1 (April 1, 2015): 51–57. http://dx.doi.org/10.1515/bvip-2015-0008.

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Abstract The objective of the study was to determine the degree of municipal wastewater contamination with intestinal parasite eggs of the genera Ascaris, Toxocara, and Trichuris at individual stages of treatment, and indication of potentially weak points in the hygienisation of sewage sludge. The study was conducted in 17 municipal mechanical-biological wastewater treatment plants which, to a slight degree, differed in the technological process of wastewater treatment and the method of hygienisation of sewage sludge. The selected treatment plants, located in seven regions, included five classified as large agglomerations (population equivalent - PE >100 000), ten as medium-size (PE 15 000-100 000), and two as smaller size with PE 10 000 - 5000. The largest number of viable eggs of Ascaris spp., Toxocara spp., and Trichuris spp. was found in the sewage sludge collected from the primary settling tank. A slightly lower number of the eggs were found in the samples of excess sludge, which indicates that the sedimentation process in the primary settling tank is not sufficiently long to effectively separate parasites’ eggs from the sewage treated. The number of eggs of Ascaris spp. and Toxocara spp. in the fermented sludge was nearly 3 times lower than that in the raw sludge. The effectiveness of hygienisation of dehydrated sewage sludge by means of quicklime was confirmed in two wastewater treatment plants, with respect to Ascaris spp. eggs, in three plants with respect to Toxocara spp. eggs, and in one plant with respect to Trichuris spp. eggs. The mean reduction of the number of eggs was 65%, 61%, and 100%, respectively. In one wastewater treatment plant, a reduction in the number of viable eggs of Ascaris and Trichuris species was also noted as a result of composting sludge by 85% and 75%, respectively. In the remaining treatment plants, no effect of hygienisation of sewage sludge was observed on the contents of viable eggs of these nematodes.

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Jinénez, B., A. Chávez, and C. Hernández. "Alternative Treatment for Wastewater Destined for Agricultural Use." Water Science and Technology 40, no. 4-5 (August 1, 1999): 355–62. http://dx.doi.org/10.2166/wst.1999.0610.

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An Advanced Primary Treatment (APT) system commercially known as ACTIFLO®, coupled with a system of filtration and chlorination are described. The system used microsand grains in the coagulation phase. This allowed an almost immediate start-up as well as an increase in loading in the sedimentation tank to rates far higher than those previously described (up to 180 m/h). The process was shown capable of treating wastewater from a combined drainage system, which typically varies in water quality and quantity. The ACTIFLO® process reduced TSS from 354 to 27 mg/L, helminth eggs from 24.8 to 1.2 HE/L, COD from 460 to 198 mg/L, TKN from 21.7 to 18.3 mg/L, and TP-P from 8.7 to 3.2 mg/L. To comply with WHO, 1989 recommendations regarding HE quality in water destined for irrigation of crops eaten raw it is necessary to add to the APT a system of filtration. In the paper two types of filter media are compared. In both cases the HE were reduced to <1.0 HE/L for filtration rates of up to 40 m/h. In the disinfection phase 10 mg Cl2/L were used to reduce the number of fecal coliforms from 6.5 × 108 to 340 MPN/100 mL.

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MAXWORTHY, T. "The dynamics of sedimenting surface gravity currents." Journal of Fluid Mechanics 392 (August 10, 1999): 27–44. http://dx.doi.org/10.1017/s002211209900556x.

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We have performed a series of experiments on the dynamics of sedimenting, surface gravity currents. The physical situation concerns a current, with total density ρC, evolving at the surface of a fluid of greater density, ρA. In turn ρC is made up of interstitial fluid of density ρI and heavy particles with a concentration by weight c and a density ρP. Only the case of the release of a constant volume of particles and interstitial fluid has been considered in detail. It has been found that the sedimentation of the particles, plus some of the interstitial fluid, through the interface between the two fluids has a profound effect upon the motion of the current. When the rejected mixture of particles and upper- and lower-layer fluids reaches the bottom of the experimental tank it generates a secondary gravity current which in turn interacts with the primary current to further modify its behaviour. Using simple models we have been able to rationalize the observations and reveal the dynamical balances which appear to be important. A subsidiary experiment and analysis on the flux characteristics of the interface have been performed in order to further clarify the important effects of the particle motion through that region.

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Hijosa-Valsero, M., V. Matamoros, R. Sidrach-Cardona, A. Pedescoll, J. Martín-Villacorta, J. García, J. M. Bayona, and E. Bécares. "Influence of design, physico-chemical and environmental parameters on pharmaceuticals and fragrances removal by constructed wetlands." Water Science and Technology 63, no. 11 (June 1, 2011): 2527–34. http://dx.doi.org/10.2166/wst.2011.500.

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The ability of several mesocosm-scale and full-scale constructed wetlands (CWs) to remove pharmaceuticals and personal care products (PPCPs) from urban wastewater was assessed. The results of three previous works were considered as a whole to find common patterns in PPCP removal. The experiment took place outdoors under winter and summer conditions. The mesocosm-scale CWs differed in some design parameters, namely the presence of plants, the vegetal species chosen (Typha angustifolia versus Phragmites australis), the flow configuration (surface flow versus subsurface flow), the primary treatment (sedimentation tank versus HUSB), the feeding regime (batch flow versus continuous saturation) and the presence of gravel bed. The full-scale CWs consisted of a combination of various subsystems (ponds, surface flow CWs and subsurface flow CWs). The studied PPCPs were ketoprofen, naproxen, ibuprofen, diclofenac, salicylic acid, carbamazepine, caffeine, methyl dihydrojasmonate, galaxolide and tonalide. The performance of the evaluated treatment systems was compound dependent and varied as a function of the CW-configuration. In addition, PPCP removal efficiencies were lower during winter. The presence of plants favoured naproxen, ibuprofen, diclofenac, salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide removal. Significant positive correlations were observed between the removal of most PPCPs and temperature or redox potential. Accordingly, microbiological pathways appear to be the most likely degradation route for the target PPCPs in the CWs studied.

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Rustige, H., and Chr Platzer. "Nutrient removal in subsurface flow constructed wetlands for application in sensitive regions." Water Science and Technology 44, no. 11-12 (December 1, 2001): 149–55. http://dx.doi.org/10.2166/wst.2001.0822.

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One of the most interesting sites for research on CWs in Germany has been established in Wiedersberg (Saxonia). The multi-stage concept with primary settling, vertical and horizontal flow reed bed followed by UV-disinfection and a special phosphorus filter bed, allows numerous ways of operation and investigations. Denitrification can be improved by recirculation through VF bed and sedimentation tank or by means of adding carbonaceous water from the primary stage to a second level within the VFB or directly to the following HF bed. In order to investigate the efficiency of P-elimination four kinds of natural sands containing different amounts of iron have been used. To maintain a long-term capacity for P-reduction an additional filter bed is filled with gravelly sand which had been used for the precipitation of iron from drinking water before. After saturating with P this filter medium can be exchanged easily. A result of more than one year of operation is the high performance rate for adsorption of phosphorus by enriched iron on drinking water filter sand. At a total loading rate of 350 g P/m3 filter medium 250 g P/m3 have been adsorbed. Design considerations can not be given yet. The median denitrification rate at VFB is 1.3 g N m-2d-1 and at HFB is 0.25 g Nm-2d-1. The low denitrifcation rate of HFB might be due to a very high quota of wastewater dilution by storm- and ground-water of 100 to 200 percent. The investigations on this wastewater treatment plant will be continued until June 2001 and experiments with filter columns will be added.

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Kwon, J. C., H. S. Park, J. Y. An, K. B. Shim, Y. H. Kim, and H. S. Shin. "Biological nutrient removal in simple dual sludge system with an UMBR (upflow multi-layer bioreactor) and aerobic biofilm reactor." Water Science and Technology 52, no. 10-11 (November 1, 2005): 443–51. http://dx.doi.org/10.2166/wst.2005.0722.

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In this study, a simple dual sludge process was developed for small sewage treatment. It is a hybrid system that consists of upflow multi-layer bioreactor (UMBR) as anaerobic and anoxic reactor with suspended growth microorganisms and post aerobic biofilm reactor with inclined plates. UMBR is a multi-function reactor that acts as primary sedimentation tank, anaerobic reactor, anoxic reactor, and thickener. The sludge blanket in the UMBR is maintained at a constant level by automatic control so that clear water (30mg-SS/L) can flow into the post aerobic biofilm reactor. It leads to improving performance of the biofilm reactor due to preventing of excess microbial attachment on the media surface and no requirment for a large clarifier caused by low solid loading. The HRT in the UMBR and the aerobic biofilm reactor were about 5.8h and 6.4h, respectively. The temperature in the reactor during this study varied from 12.5°C to 28.3°C. The results obtained from this study show that effluent concentrations of TCOD, TBOD, SS, TN, and TP were 29.7mg/L, 6.0mg/L, 10.3mg/L, 12.0mg/L, and 1.8mg/L, which corresponded to a removal efficiency of 92.7%, 96.4%, 96.4%, 74.9%, and 76.5%, respectively. The sludge biomass index (SBI) of the excess sludge in the UMBR was about 0.55, which means that the sludge in the UMBR was sufficiently stabilized and may not require further treatment prior to disposal.

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Zejda, Vojtěch, Vítězslav Máša, Šárka Václavková, and Pavel Skryja. "A Novel Check-List Strategy to Evaluate the Potential of Operational Improvements in Wastewater Treatment Plants." Energies 13, no. 19 (September 23, 2020): 5005. http://dx.doi.org/10.3390/en13195005.

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With increasing demands for cleaning and purification of water, wastewater treatment plants (WWTP) require their most efficient operation. The operators are thus obliged to constantly review the efficiency of the processing units and technological equipment of WWTPs and seek opportunities for improvements. To increase the efficiency of particular equipment, the important parameters to be used for the intensification must be correctly selected. A common WWTP consists of different types of processing units, where the basic parameters can be changed to achieve the highest efficiency (i.e., maximum output with minimum energy consumption) in the WWTP. However, due to many possible technologies in the wastewater treatment process, the combinations of processing units can be complex. In such cases, the efficiency assessment can be misleading if only basic parameters were accessed. Moreover, single-unit intensification can potentially improve the efficiency of the unit itself but cannot guarantee full process improvement. This can be due to negative causal effects in the downstream due to that unit intensification. This work reviews of key parameters at five selected pieces of WWTP equipment (inlet pump station, airlift pump, primary sedimentation tank, aeration chamber, and mixing of anaerobic digester) to demonstrate the correct selection of all affected parameters for the efficiency assessment. In the context of the whole WWTP process, it is necessary to take into account several other parameters to evaluate the efficiency of the equipment. Finally, a methodology for assessing the significance of the identified parameters is proposed. This methodology is effectively applied and demonstrated in the WWTP case study.

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Chen, Jie Yun, Zhi Zhang, Li Hua Xie, Ling Kong, and Xiao Jing Yin. "Regulating Strategies of Strengthening Nitrogen Removal for Low-Carbon Wastewater in Reversed A²/O Process." Advanced Materials Research 243-249 (May 2011): 4811–16. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.4811.

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According to the ineffective denitrification and the initial controlling technique flaws for low-carbon source in reversed A2/O process, and full scale experimental studies were conducted to strengthen denitrification at normal and low temperature days in 2008~2010, to ensure the best conditions of biological denitrification and promote the stable and efficient operation of the system. The results showed that in normal temperature seasons of 2008, after shortening the HRT of the primary sedimentation tank to 1/3 of design value, improving the MLSS to 4500mg/L, setting the first section of the aerobic zone as the denitrification transition section and improving the reflux ratio, available carbon source was increased by 15%, the effluent NH3-N was 2.5mg / L and the removal rate was 90%, the effluent TN was 17 mg/L and the removal rate was increased to 54% and unit power consumption was reduced by 15% to 0.22Kw•h/m3.At low temperature seasons of 2008~2009,by improving the MLSS to 6000mg/L, extending the sludge age to enrich a large number of nitrification and denitrification bacteria, controlling DO at about 1.2mg / L in the aerobic zone and so on, the effluent NH3-N was 3 mg / L and the removal rate was 88%, the effluent TN was 15.5 mg/L and the removal rate was 62%. In low temperature of 2009 ~2010, besides the same measures as before, adding a blender in the first section of the aerobic zone to provide a better anoxic environment for denitrification and to improve nitrogen removal, the effluent NH3-N was 3 mg / L and the removal rate was 87%, the effluent TN was 13.5 mg/L and the removal rate was 66%.

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Moruzzi, R. B., J. Bridgeman, and P. A. G. Silva. "A combined experimental and numerical approach to the assessment of floc settling velocity using fractal geometry." Water Science and Technology 81, no. 5 (March 1, 2020): 915–24. http://dx.doi.org/10.2166/wst.2020.171.

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Abstract Sedimentation processes are fundamental to solids/liquid separation in water and wastewater treatment, and therefore a robust understanding of the settlement characteristics of mass fractal aggregates (flocs) formed in the flocculation stage is fundamental to optimized settlement tank design and operation. However, the use of settling as a technique to determine aggregates' traits is limited by current understanding of permeability. In this paper, we combine experimental and numerical approaches to assess settling velocities of fractal aggregates. Using a non-intrusive in situ digital image-based method, three- and two-dimensional fractal dimensions were calculated for kaolin-based flocs. By considering shape and fractal dimension, the porosity, density and settling velocities of the flocs were calculated individually, and settling velocities compared with those of spheres of the same density using Stokes' law. Shape analysis shows that the settling velocities for fractal aggregates may be greater or less than those for perfect spheres. For example, fractal aggregates with floc fractal dimension, Df = 2.61, floc size, df > 320 μm and dp = 7.5 μm settle with lower velocities than those predicted by Stokes' law; whilst, for Df = 2.33, all aggregates of df > 70 μm and dp = 7.5 μm settled below the velocity calculated by Stokes' law for spheres. Conversely, fractal settling velocities were higher than spheres for all the range of sizes, when Df of 2.83 was simulated. The ratio of fractal aggregate to sphere settling velocity (the former being obtained from fractal porosity and density considerations), varied from 0.16 to 4.11 for aggregates in the range of 10 and 1,000 μm, primary particle size of 7.5 μm and a three-dimensional fractal dimension between 2.33 and 2.83. However, the ratio decreases to the range of 0.04–2.92 when primary particle size changes to 1.0 μm for the same fractal dimensions. Using the floc analysis technique developed here, the results demonstrate the difference in settlement behaviour between the approach developed here and the traditional Stokes' law approach using solid spheres. The technique and results demonstrate the improvements in understanding, and hence value to be derived, from an analysis based on fractal, rather than Euclidean, geometry when considering flocculation and subsequent clarification performance.

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Voit, Kevin, Joseph Kwiatkowski, Jennifer Ehrhardt, Jim Marx, Salil Kharkar, Walter Bailey, Sudhir Murthy, and John Carr. "Evaluating Odor Control Engineering Solutions for Primary Sedimentation Tanks Using Air Dispersion Modeling." Proceedings of the Water Environment Federation 2014, no. 12 (October 1, 2014): 6613–24. http://dx.doi.org/10.2175/193864714815940019.

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Shahrokhi, Mahdi, Fatemeh Rostami, Md Azlin Md Said, Saeed Reza Sabbagh Yazdi, and Syafalni Syafalni. "Computational investigations of baffle configuration effects on the performance of primary sedimentation tanks." Water and Environment Journal 27, no. 4 (October 22, 2012): 484–94. http://dx.doi.org/10.1111/j.1747-6593.2012.00367.x.

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Cowburn, Scott L., and David W. Borneman. "High-Rate Operation of Primary Sedimentation Tanks to Provide Additional Wet-Weather Treatment Capacity." Proceedings of the Water Environment Federation 2008, no. 17 (January 1, 2008): 411–27. http://dx.doi.org/10.2175/193864708788735448.

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42

Shahrokhi, Mahdi, Fatemeh Rostami, Md Azlin Md Said, Saeed Reza Sabbagh Yazdi, and Syafalni. "The effect of number of baffles on the improvement efficiency of primary sedimentation tanks." Applied Mathematical Modelling 36, no. 8 (August 2012): 3725–35. http://dx.doi.org/10.1016/j.apm.2011.11.001.

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43

Shahrokhi, Mahdi, Fatemeh Rostami, Md Azlin Md Said, and Syafalni. "Numerical modeling of baffle location effects on the flow pattern of primary sedimentation tanks." Applied Mathematical Modelling 37, no. 6 (March 2013): 4486–96. http://dx.doi.org/10.1016/j.apm.2012.09.060.

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Liu, Qi Wei, and Xiao Yu Zhang. "The Characteristics of the Mixed Sludge Supernatant by Mesophilic Two-Phase Anaerobic Digestion Process." Applied Mechanics and Materials 295-298 (February 2013): 1393–97. http://dx.doi.org/10.4028/www.scientific.net/amm.295-298.1393.

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The mesophilic (35°C) two-phase anaerobic digestion ( TPAD) process was used to treat mixed sludge from primary sedimentation and secondary sedimentation tanks ( 1:3 ). The results show that when HRT is 10 days and organic loading rate is 1.5kgVS/ (m3•d), the upper-liquid COD of methanogenic phase and acidogenic phase increased along with time, but not obviously; The contents oSuperscript textf polysaccharides and proteins in upper-liquid multiplied increased with digestion time, polysaccharides and proteins in acidogenic phase upper-liquid were more than methanogenic phase; The value of CST became larger after being digested by mesophilic two-phase anaerobic digestion, but the dewaterability of sludge in methanogenic phase is better than acidogenic phase.

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45

Adamski, R. E., V. DeSantis, A. Spangel, J. Pynn, L. Betty, C. M. Koch, and S. A. Gyory. "Step-feed operation at short detention times – a cost effective method for improving wastewater treatment." Water Science and Technology 41, no. 9 (May 1, 2000): 15–20. http://dx.doi.org/10.2166/wst.2000.0159.

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The Newtown Creek Water Pollution Control Plant (WPCP) is New York City's largest wastewater treatment plant. Wastewater treatment is provided by a high-rate activated sludge process without primary sedimentation. This process has achieved approximately 65 percent BOD5 and 75 percent TSS removal. As part of a revised facility plan, two alternative tracks were recommended for upgrading the plant to secondary treatment and providing nitrogen removal. One track would require demolishing most of the existing tankage and constructing new primary tanks followed by a step-feed biological nitrogen removal activated sludge process. The second track would preserve the existing high-rate activated sludge process and use biological filters to remove additional TSS, BOD5 and nitrogen. Alternatives have been investigated to enhance treatment at the Newtown Creek WPCP while the secondary treatment plant upgrading is being completed. This investigation demonstrated that simply converting the existing aeration tanks to step-feed operation could significantly improve TSS and BOD removals. These findings have led the City to consider a third track to meet secondary treatment requirements, (but with no nitrogen removal), consisting of modifying the existing plant to step-feed and adding additional step-feed aeration/sedimentation capacity. This track offers significant cost savings over Track 1 and Track 2.

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Jover-Smet, Margarita, Jaime Martín-Pascual, and Arturo Trapote. "Model of Suspended Solids Removal in the Primary Sedimentation Tanks for the Treatment of Urban Wastewater." Water 9, no. 6 (June 21, 2017): 448. http://dx.doi.org/10.3390/w9060448.

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K.M., Ho, Tam L.S., Gerges H., Chan M., Law D., and Tang D. "Smarter and Greener Design and Operation of Primary Sedimentation Tanks Using Three-Dimensional Computational Fluid Dynamic Modeling." Proceedings of the Water Environment Federation 2018, no. 18 (January 1, 2018): 122–32. http://dx.doi.org/10.2175/193864718825138088.

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Ramadori, R., V. Tandoi, and A. Misiti. "Bench Scale and Pilot Scale Experiments on Biological Phosphorus Removal." Water Science and Technology 17, no. 11-12 (November 1, 1985): 287–88. http://dx.doi.org/10.2166/wst.1985.0240.

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In connection with studies aimed at developing low-energy wastewater treatment processes considerable interest has been shown in the possibility of removal of phosphorus biologically rather than chemically. The results over one year from bench and pilot scale tests conducted with synthetic and settled domestic wastewaters respectively are reported. The pilot plant was installed in one of the Rome urban wastewater treatment works and consisted of a two stage (anaerobic-aerobic) system. The wastewater was withdrawn downstream from the primary settling tank and conveyed to the anaerobic reactor of the pilot plant. A similar experiment was conducted in a three reactor (two anaerobic and one aerobic) bench scale plant, where a synthetic solution (peptone, sodium acetate and potassium phosphate) was fed under rigorously controlled conditions of temperature, pH and dissolved oxygen. Both bench and pilot scale tests were designed to verify and quantify the biological removal of phosphorus; the performances of both phosphorus removal test scale systems were compared with those from a reference aerobic plant operating under the same conditions. The impact of several parameters on the biological removal of phosphorus were examined. These parameters were: nature of carbonaceous substrate, carbonaceous/phosphorus ratio, sludge age; etc. Considerable care and attention was given to checking phosphorus balances, once the steady state conditions had been obtained. The results can be summarized as follows:-Phosphorus removal was found to be greater in plants with an anaerobic stage than in the reference plants. At pilot scale level this is clearly shown by the plot of the daily phosphate concentration in the effluents. At bench scale it is shown by comparison between P contents in sludges (9.9% vs. 5.0%) and by the fact that, at the end of the experiment, large deposits of inorganic phosphate (mainly of Ca and Mg) were found on the walls of both anaerobic reactors. The unstable operating conditions of the reference plant due to the poor sedimentation characteristics of the sludges leading to uncontrolled losses of biomass meant it was impossible to obtain a reliable mean phosphorus abatement value, which in any case was always well below that found for the P-removal plant.-As reported above, the deficit in the phosphorus balance was due to inorganic phosphate precipitation. In this connection an excellent quantitative agreement was found between the deficit in the balance and the quantity of phosphorus collecting in the anaerobic reactors.-Phosphorus release from the biomass under anaerobic conditions has already been completed in the first anaerobic reactor (where carbonaceous substrate uptake also occurs) and the use of the second anaerobic reactor seems to allow a more complete phosphate precipitation.-Part of the carbonaceous substrate which disappears during the first anaerobic stage is metabolized. In fact, in this reactor, the complete disappearance of organic nitrogen is accompanied by the release of large quantities of ammoniacal nitrogen. Lastly, despite the fact that the values of the main operative parameters, such as hydraulic retention time, sludge age, temperature, pH and dissolved oxygen, were kept rigorously constant, a certain instability was found in the biomass as regards the maintaining of such high phosphorus removal efficiencies over long periods of time. This may be due to the highly variable biological population dynamics.

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Klaucans, Elvis, and Karlis Sams. "Problems with Fat, Oil, and Grease (FOG) in Food Industry Wastewaters and Recovered FOG Recycling Methods Using Anaerobic Co-Digestion: A Short Review." Key Engineering Materials 762 (February 2018): 61–68. http://dx.doi.org/10.4028/www.scientific.net/kem.762.61.

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Food production industry is the main producer of wastewaters with high fat, oil, and grease (FOG) content. FOG waste can be recovered from the wastewater stream by using physicochemical methods and reused considering their high methane potential. Popular method of FOG reuse is anaerobic co-digestion (AcoD) with wastewater treatment sludge and scum from the primary wastewater sedimentation tanks. This short review focuses on understanding the efficiency of FOG reuse possibilities by AcoD and takes a closer look at problems connected to degradation issues, gives an understanding on microbial changes during FOG degradation, and reviews enzymes involved in the degradation process.

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Sadrnejad, S. A. "Nitrification Processes in Tehran Wastewater Treatment Plant." ISRN Mechanical Engineering 2011 (May 31, 2011): 1–9. http://dx.doi.org/10.5402/2011/545794.

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A wastewater treatment plant is designed to daily treat 450000 m3 of wastewater collected from the city of Tehran. The wastewater treatment plant is located at the south of Shahr-Ray in southern Tehran with the area of 110 hectares. The treatment plant effluent will be transferred to Varamin agricultural lands to be used for the irrigation of crops. A conventional activated sludge for carbon removal and a high-rate trickling filter for nitrification of ammonia to nitrate are designed and constructed. The treatment plant consists of inlet pumping station, primary treatment, primary sedimentation tanks, selector and aeration tanks, trickling filter, and sludge treatment units. A mass balance analysis method which is a new approach for optimum design is used to achieve cost saving for the construction of south Tehran wastewater treatment plant. The comparison between combined system of activated sludge with trickling filter and an activated sludge alone shows that the combined system is 20% less costly and more efficient for the treatment of Tehran wastewater, the system has low volume demand, maximum biogas yeild, and low process control and is less variable to pH and chemical effects and highly energy-efficient.

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Journal articles on the topic 'Primary sedimentation tank'

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