Journal articles on the topic 'Batch digesters. eng'

Anaerobic digestion is widely used for wastewater treatment, especially in the food industries. Generally after the anaerobic treatment there is an aerobic post-treatment in order to return the treated water to nature. Several technologies are applied for winery wastewater treatment. They are using free cells or flocs (anaerobic contact digesters, anaerobic sequencing batch reactors and anaerobic lagoons), anaerobic granules (Upflow Anaerobic Sludge Blanket – UASB), or biofilms on fixed support (anaerobic filter) or on mobile support as with the fluidised bed. Some technologies include two strategies, e.g. a sludge bed with anaerobic filter as in the hybrid digester.With winery wastewaters (as for vinasses from distilleries) the removal yield for anaerobic digestion is very high, up to 90–95% COD removal. The organic loads are between 5 and 15 kgCOD/m3 of digester/day. The biogas production is between 400 and 600 L per kg COD removed with 60 to 70% methane content. For anaerobic and aerobic post-treatment of vinasses in the Cognac region, REVICO company has 99.7% COD removal and the cost is 0.52 Euro/m3 of vinasses.

Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for overcoming these limitations. In this study, continuous anaerobic digestion (AD) of manure mixed with optimally AAS-treated manure fibers was compared to the AD of manure mixed with untreated manure fibers. Due to lab-scale pumping restrictions, the ratio of AAS-optimally treated manure fibers to manure was only 1/3 on a total solids (TS) basis. However, the biogas productivity and methane yield were improved by 17% and 38%, respectively, also confirming the predictions from a simplified 1st order hydrolysis model based on batch experiments. Furthermore, an improved reduction efficiency of major organic components was observed for the digester processing AAS-treated manure fibers compared to the non-treated one (e.g., 42% increased reduction for cellulose fraction). A preliminary techno-economic analysis of the proposed process showed that mixing raw manure with AAS manure fibers in large-scale digesters could result in a 72% increase of revenue compared to the AD of manure mixed with untreated fibers and 135% increase compared to that of solely manure.

Pre-concentration of municipal wastewater by chemically enhanced primary treatment (CEPT) was studied under controlled laboratory conditions. Both iron and aluminium-based coagulants were examined at gradually increasing concentrations (0.23, 0.35, 0.70 and 1.05 mmol/L). The CEPT sludge generated from different coagulation experiments was digested in batch anaerobic reactors, while the supernatant was tested in a dead-end microfiltration setup. The results of the study show that biogas yield was dramatically decreased (from 0.40 to 0.10 m3/kg chemical oxygen demand of influent) with increasing coagulant dose. In contrast, supernatant filterability was improved. Based on the laboratory results, a conceptual design was produced for a community of 2000 inhabitant equivalents (IE), using CEPT technology (at low coagulant dose) with anaerobic digestion of the concentrates. According to this, the capital and operational costs were 0.11 and 0.09 €/m3, respectively. The biogas generated is used for digester heating and the overall process is energy self-sufficient. At a small-scale and in private applications, CEPT technology is preferably operated at higher coagulant dose, followed by membrane filtration for water reuse. Accordingly, sewage purification and reuse is possible without implementing aerobic biological processes.

ABSTRACT Aiming to evaluate different wastewaters in the anaerobic co-digestion (ACoD) of hatchery wastes, a batch test was conducted in bench horizontal digesters. At the end of the process, the potential production of biogas and methane was calculated as well as the chemical composition (macro- and micronutrients) of the effluent and the concentrations of methane and carbon dioxide gas at 60 days. The monitoring of the process included observations of the reduction of the organic carbon, chemical oxygen demand, and total (TS) and volatile solids (VS), as well as the variation of pH and electrical conductivity (EC). The results showed that the mixing between the hatchery fresh waste and swine wastewater (T4) and among fresh hatchery waste, water from the first anaerobic pond of the hatchery and swine wastewater (T5) represent significant sources of renewable energy and thereby greater potential for biogas production (192.50 and 205.0 L biogas per kg of VS added to T4 and T5, respectively). The average concentration of methane in the biogas varied from 72 to 77% among the treatments. For all treatments, reductions were observed in TS and VS and increases in pH and EC. It was concluded that the energy recovery from hatchery wastes is favoured by the addition of swine wastewater in the ACoD process.

Sunflower residues are considered a prominent renewable source for biogas production during anaerobic digestion (AD). However; the recalcitrant structure of this lignocellulosic substrate requires a pretreatment step for efficient biomass transformation and increased bioenergy output. The aim of the present study was to assess the effect of alkaline pretreatment of various parts of the sunflower residues (e.g., heads and stalks) on their methane yield. Experimental data showed that pretreatment at mild conditions (55 °C; 24 h; 4 g NaOH 100 g−1 total solids) caused an increase in the biochemical methane potential (BMP) of both heads and stalks of the sunflower residues as determined in batch tests. The highest methane production (268.35 ± 0.11 mL CH4 g−1 volatile solids) was achieved from the pretreated sunflower head residues. Thereafter; the effect of alkaline pretreatment of sunflower head residues was assessed in continuous mode; using continuous stirred-tank reactors (CSTRs) under two operational phases. During the first phase; the CSTRs were fed with the liquid fraction produced from the pretreatment of sunflower heads. During the second phase; the CSTRs were fed with the whole slurry resulting from the pretreatment of sunflower heads (i.e., both liquid and solid fractions). In both operating phases; it was observed that the alkaline pretreatment of the sunflower head residues had a negligible (phase I) or even a negative effect on biogas production; which was contradictory to the results of the BMP tests. It seems that; during alkaline pretreatment; this part of the sunflower residues (heads) may release inhibitory compounds; which induce a negative effect on biogas production in the long term (e.g., during continuously run digesters such as CSTR) but not in the short-term (e.g., batch tests) where the effect of the inoculum may not permit the inhibition to be established.

An attractive way of recovering essential phosphorus from digested sludge of a WWTP is the precipitation in the sludge directly, as part of the continuous treatment process. For optimizing the precipitation, 1 litre-batch tests were performed in a model system to examine the MAP-crystallization kinetics. Different parameters such as e.g. the aeration flow rate were investigated. The aim was to find an optimized setting for a pilot reactor for the continuous production of MAP. This reactor performed as an airlift reactor for an improved mixing and stripping the dissolved CO2 and separating the MAP-crystals. The optimal condition for the airlift pilot reactor is given when the air flow rate for mixing the system and for stripping CO2 for a maximum MAP precipitation is aligned with the particle size distribution.

Wastewaters generated from agricultural industries are usually hard to treat due to a high organic content. The basic treatment process to be used can only be anaerobic digestion, a process with the additional advantages of (i) limited production of stabilized sludge and (ii) utilization of the produced biogas. The cotreatment of such seasonally produced wastewaters is proposed in order to secure the economically favorable and stable year-round operation of a treatment plant, with the additional benefits of smaller capital costs (due to the use of centrally located rather than distributed treatment facilities) and the exploitation of complementarity in waste characteristics (e.g. avoidance of nutrients (N,P) addition when a codigested wastewater contains nutrients in excess). A mathematical model for codigesting piggery, olive-mill and dairy wastewaters was developed based on batch kinetic experiments. An organic loading rate of 3.84 g COD/l·d was found to be safe for a digester operating on a year-round basis, fed sequentially with piggery, piggery-olive-mill and piggery-dairy wastewaters.

Many waste water treatment plants in Sweden have been using pre-precipitation, which has considerably decreased the load on the existing activated sludge process. In many cases it has been possible to introduce predenitrification, with minor changes or increase of volume, in order to reach the required effluent values, which in Sweden varies between 10 and 15 mg Ntot/l as annual average value. In treatment plants with anaerobic digestion of sludge, some 15–20% of the nitrogen load is recirculated with the return liquors from dewatering. Separate treatment of ammonia-rich return liquors has successfully been using SBR-technique for nitrogen removal, adding external carbon source, e.g. methanol or ethanol. The overall result is, however, not sufficient to meet the requirement, without additional action. The use of SBR-reactors, designed for nitrification/denitrification of return liquors from dewatering of digested sludge, and part of the influent raw waste water, 20–30%, as a carbon source, has been proven most cost-effective, both from investment and operation cost point of view. The result is a considerably decreased load on the existing biological stage, making it possible to introduce pre-denitrification without any extension of reaction volumes. The paper presents the result from full-scale operation of some plants in Sweden.

Homoacetogenic bacteria are strict anaerobes capable of autotrophic growth on H2/CO2 or CO, and of heterotrophic growth on a wide range of sugars, alcohols, methoxylated aromatic compounds and one carbon compounds, yielding acetate as their sole metabolic end-product. Batch activity tests on anaerobic granular sludge, using H2/CO2 as a substrate and 2-bromoethanesulfonate (BES) as a specific methanogenic inhibitor revealed that H2/CO2 conversion and concomitant acetate production commenced only after a lag period of 60–100 h. This finding suggests that the homoacetogenic population of digester sludge could be maintained by heterotrophic growth on sugars or other organic compounds, rather than by autotrophic growth on H2/CO2. In the present study, two upflow anaerobic sludge bed (UASB) reactors were operated at 37°C and 55°C for two distinct trial periods, each characterised by the application of influents designed to enrich for homoacetogenic bacteria. Specific primers designed for the amplification of the functional gene encoding formyltetrahydrofolate synthetase (FTHFS), a key enzyme in the acetyl-CoA pathway of acetogenesis, were used as a specific probe for acetogenic bacteria. The diversity of acetogens in the granular sludge cultivated in each reactor was revealed by application of FTHFS targeted PCR. Results show that biomass acetogenic composition was dependent upon the operational temperature of the reactor and the substrate supplied as influent.

A new Actinidia chinensis gold-fleshed kiwifruit cultivar ‘Zesy002’ was tested to investigate whether it could positively modulate the composition of the human colonic microbiota. Digested Zesy002 kiwifruit was added to in vitro pH-controlled anaerobic batch fermenters that were inoculated with representative human faecal microbiota. Alterations to the gut microbial ecology were determined by 16S rRNA gene sequencing and metabolic end products were measured using gas chromatography and liquid chromatography – mass spectrometry. Results indicated a substantial shift in the composition of bacteria within the gut models caused by kiwifruit supplementation. Zesy002 supplemented microbiota had a significantly higher abundance of Bacteroides spp., Parabacteroides spp. and Bifidobacterium spp. after 48 h of fermentation compared with the start of the fermentation. Organic acids from kiwifruit were able to endure simulated gastrointestinal digestion and were detectable in the first 10 h of fermentation. The fermentable carbohydrates were converted to beneficial organic acids with a particular predilection for propionate production, corresponding with the rise in Bacteroides spp. and Parabacteroides spp. These results support the claim that Zesy002 kiwifruit non-digestible fractions can effect favourable changes to the human colonic microbial community and primary metabolites, and demonstrate a hitherto unknown effect of Zesy002 on colonic microbiota under in vitro conditions.

Liquor rejected from the centrifugation of the digested sludge can contain the concentrations of ammonium ions up to 1750 mg/L. These loads are usually returned to the intake of wastewater treatment plants (WWTP) without additional treatment and can have a negative impact on biological wastewater and/or sludge treatment processes, e.g. phosphorus and nitrogen removal. This article deals with the use of naturally obtained sorbent, zeolite, in batch and column test procedure for removing ammonium from the rejected liquor. This research study was carried out using different sizes of zeolite particles: 0.8–1.6 mm and 1.6–2.5 mm. The highest efficiency of ammonium removal (up to 98 %) was achieved by applying the zeolite particles of 0.8–1.6 mm. Article in Lithuanian. Santrauka Sausinant pūdytą dumblą centrifugomis išsiskiria skystis, kuriame gali būti didelės amonio jonų koncentracijos (iki 1750 mg/l). Taip užterštas ir papildomai nevalytas dumblo vanduo, grąžinamas į nuotekų valymo įrenginių pradžią, gali trukdyti nuotekų ar dumblo valymo procesams, būtent, kai siekiama pašalinti azotą ir fosforą. Nagrinėjamas gamtinio sorbento ceolito panaudojimas amonio jonams šalinti iš dumblo vandens maišaluose ar skystį filtruojant pro ceolito užpildus. Tyrimams naudota 0,8–1,6 mm ir 1,6–2,5 mm dydžio ceolito grūdeliai. Didžiausias amonio jonų šalinimo iš skysčio efektyvumas (iki 98 %) buvo pasiektas, kai ceolito grūdeliai 0,8–1,6 mm dydžio.

A novel anaerobic, chemo-organotrophic, sulfate-reducing bacterium, designated strain Olac 40T, was isolated from a Tunisian wastewater digestor. Cells were curved, motile rods or vibrios (5.0–7.0×0.5 µm). Strain Olac 40T grew at temperatures between 15 and 50 °C (optimum 40 °C), and between pH 5.0 and 9.0 (optimum pH 7.1). It did not require NaCl for growth but tolerated it up to 50 g l−1 (optimum 2 g l−1). In the presence of sulfate or thiosulfate, strain Olac 40T used lactate, pyruvate and formate as energy sources. Growth was observed on H2 only in the presence of acetate as carbon source. In the presence of sulfate or thiosulfate, the end products of lactate oxidation were acetate, sulfide and CO2. Sulfate, thiosulfate and sulfite were used as terminal electron acceptors, but not elemental sulfur, nitrate or nitrite. The genomic DNA G+C content of strain Olac 40T was 70 mol%. The profile of polar lipids consisted of phosphatidylglycerol, phosphatidylethanolamine, aminophospholipid and four phospholipids. The main fatty acids were C16 : 0, anteiso-C15 : 0 and iso-C15 : 0. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain Olac 40T was affiliated with the family Desulfovibrionaceae within the class Deltaproteobacteria . On the basis of 16S rRNA gene sequence comparisons and physiological characteristics, strain Olac 40T is proposed to be assigned to a novel species of the genus Desulfocurvus , for which the name Desulfocurvus thunnarius is proposed. The type strain is Olac 40T ( = DSM 26129T = JCM 18546T).

This work investigated the potential of generating biogas from mono-digestion of various substrates such as food and fruit waste (e.g., durian shell, dragon fruit peel and pineapple peel) and co-digestion in different combinations of a co-substrate as food waste as well as different types of fruit waste (durian shell, dragon fruit peel and pineapple peel). The mixture of food waste and fruit waste ratio varied as follows: 75:25, 50:50 and 25:75, which was based on weight. The batch experiments were carried out using 125 ml anaerobic digesters and were incubated for 50 days. For a mono-substrate, food waste produced the highest amount of methane gas (60.63 ± 1.02 ml/gvs) followed by durian shell (34.93 ± 1.30 ml/gvs), pineapple peel (31.70 ± 1.60 ml/gvs), and dragon fruit peel (30.12 ± 1.20 ml/gvs), respectively. The highest amount of methane gas came from food waste mixed with durian shell (FW75:D25), and it was on a higher level than food waste mixed with dragon fruit peel (FW75:DF25) and pineapple peel (FW75:P25). The highest methane gas production of co-digestion which was observed at the proportion of food waste and durian shell was 75:25 and produced higher content of methane gas than the highest methane gas production of mono-digestion (food waste) according to the high organic compound and optimum pH value in the system. The results showed that the co-digestion of durian shell and food waste improved methane production and reduced the startup time compared with their mono-digestion. On the other hand, pineapple peel was not suitable for co-digestion with food waste due to a decreasing pH value in the system.

Biogas production considered the most encouraging sources of renewable energy in Sudan. Anaerobic process of digestion is considered as efficient techniques of producing biogas. The process also a trustworthy method for treatment of municipal wastes, and the digested discharge could be utilized as soil conditioner to improve the productivity. This research work states at the option of using domestic sludge of the wastewater treatment plant in Soba municipal station (south of Khartoum-Sudan) to produce biological gas (biogas). A laboratory investigation was carried out using five-liter bioreactor to generate biogas for 30 days. The total volume of gas made was 270.25 Nml with a yield of 20 Nml of biogas/mg of COD removed. Chemical oxygen demand, Biological oxygen demand, & total solids drop produced were 89, 91 & 88.23% respectively. Microbial activity was declined from 1.8x107 (before starting the process of digestion) to 1.1x105 germs/mL (after completion of 30 days of digestion). This study offered a significant energetic opportunity by estimated the power production to 35 KWh.Key word: Sludge, municipal plant, organic material, anaerobic process, breakdown, biological gas potentialNTRODUCTIONIncreasing of urban industries style in the world has given rise to the production of effluents in huge amounts with abundant organic materials, which if handled properly, be able to end in a substantial source of energy. Although of a fact that there is an undesirable environmental effect related with industrialization, the influence can be diminished and energy can be tapped by means of anaerobic digestion of the wastewater (Deshpande et al., 2012). Biological wastewater treatment plant (WWTP) is a station for removal of mainly organic pollution from wastewaters. Organic materials are partly transformed into sludge that, with the use of up-to-date technologies, represents an important energy source. Chemical biological, and physical technology applied throughout handling of wastewater produce sludge as a by-product. Recent day-to-day totals, dry solids range from 60–90 g per population equivalent, i.e. EU produces per year 10 million tons of dry sludge (Bodík et al., 2011). Sludge disposal (fertilizers use, incineration, and landfills) is often explored since of increasingly limiting environmental legislation (Fytili and Zabaniotou, 2008). The energy present in sludge is obviously consumed in anaerobic digestion. Anaerobic Process is considering the most appropriate choice for the handling of organic effluents of strong content. This process upgraded in the last few years significantly with the applications of differently configured high rate treatment processes, particularly for the dealing of industrial releases (Bolzonella et al., 2005). Anaerobic process leads to the creation of biological gas with high content of methane, which can be recovered, and used as an energy source, making it a great energy saver. The produced gas volume during the breakdown process can oscillate over a wide range varying from 0.5 – 0.9 m3 kg–1 VS degraded (for waste activated sludge) (Bolzonella et al., 2005). This range rest on the concentration of volatile solids in the sludge nourish and the biological action in the anaerobic breakdown process. The residue after digestion process is stable, odorless, and free from the main portion of the pathogenic microorganism and finally be able to use as an organic nourishment for different application in agriculture. Sludge significant coming out from breakdown which allows to yield a renewable energy, that was cheap, obtainable, & no polluting. Sustainable development considered the production of biogas as environmentally friendly and an economic key (Poh and Chong, 2009).OBJECTIVES Sudan have huge tones of sewage sludge from domestic sewage water is accumulated daily in lagoon of soba sewage treatment plant, so this work, we were carried for energy production and treatment of sludge, which constitutes a plentiful waste which ever know any sort of handling after few years from establishing the station.MATERIALS AND METHODSExperimental apparatus: Anaerobic breakdown was done in five liters fermenter. The fermenter was maintained at 35oC in a thermostatic bath and stirred regularly. U shaped glass tube was connected to the fermenter, allowing the measurement of produced biogas volume and pressure. Water displacement technique was used for determination of the volume of produced biological gas (biogas) at the beginning of each sampling. Testing of the biogas combustibility was determined by connecting one of ends of the tube to a gas collection and storage device (balloon), the other end to a Bunsen burner. In the process of reduction of carbon dioxide (CO2) to maximum dissolution in the tube the liquid must be a salty saturated acid solution (5% citric acid, 20% NaCl, pH ¼ 2) (Connaughton et al., 2006).Substrate: About 5L sludge containing culture medium were taken from the lowest part of the first settling tank in Soba station. The moisture content of initial substrate was 35%. The collected sample was preserved at 4oC prior to loading the biological reactor (Tomei et al., 2008). Table 1 showed the sludge features in the reactor with a loading rate of 16 g TS/L, (Connaughton et al., 2006; Tomei et al., 2008).Analytical Methods: The pH was controlled by using HANNA HI 8314 model as pH meter device. Assay was used for determination of Alkanility & Volatile fatty acids (Kalloum et al., 2011). The standard method of analysis was used for recognized the Chemical Oxygen Demand (COD) (Raposo et al., 2009). Titrimetric method was used for analyzing Volatile fatty acids (VFA). Alkalinity assay was used for determination of Total Alkalinity (TA). Oxitop assay was used for measuring the biological oxygen demand. Ignition method was used for measuring Volatile Solids (VS) by losing weight in dry sample at 550oC in the furnace, & Total solids were done to constant weight at 104oC (Monou et al., 2009). A method of water displacement was used for determination of the total volume of Biological gas produced (Moletta, 2005). Microbial species & analyses were determined by microbial standard assay. Sample analysis was done by explore of three replicates and the outcomes were the middling of these replicates. Startup of experiments continues until a bubble of gas was detected.RESULTS AND DISCUSSIONMeasurement of pH: Figure 2 exhibited pH trends during 30 days with a drop pattern from 7.0 to 6.0 during the first five days; this was mainly because of the breakdown of organic materials and the development of (VFA). Then later, an increasing pattern in pH was noticed to 6.98, for the next week, then Steadying around this pH level was continued till the completion of the breakdown period which taken 30 days. Those out comes were also reported by other researchers (Raposo et al., 2008)Measurement of VFA: Development of VFA throughout 30 days was depicted in figure 3, an increase in volatile fatty acids up to 1400 mill equivalents per liter (meq/L) in the first ten days. This criterion of making of volatile fatty acid is typical to the researcher’s report of identification of hydrolysis in acidogenesis stage (Parawira et al., 2006). The decline in volatile fatty acids after the tenth day was owing to intake by bacteria which would relate to the stage of acetogenesis.Total alkalinity (TA): During the ten days, we observed rise in volatile fatty acids content followed by a drop in a pH in the same time (figures 4 and 5). Encountered to these alterations, an increase in the total alkalinity in the medium for reestablishing situations of alkalinity to the outbreak of methanogens stage (figure 4). Through all the digestion period the ratio of VFA/TA which was equal and lower than 0.6±0.1 were described in figure 6. These ratios designated the achievability of the procedure despite the essential production of volatile fatty acid (Chen and Huang, 2006; Nordberg et al., 2007). The anaerobic digestion process may be hinder by the production of volatile fatty acid.Biogas production: Pressure measurement and biogas volume were used for controlling biogas production. Figure 7 explained the changing in biogas pressure throughout the digestion period. quality of Biogas was obtained with minimum methane of 40% (Bougrier et al., 2005; Lefebvre et al., 2006). Total volume of biological gas production was 270.25 Nml. The yield of biological gas was 20.25 Nml/mg COD removed, which is in range of the others researcher report (Tomei et al., 2008). Biogas production can be calculated from the following formula (Álvarez et al., 2006): Biogas production= (Total quantity of biogas produced)/(Total solid).The COD and BOD removal: Chemical oxygen Demand (COD) and Biological Oxygen Demand (BOD) showed a significant reduction of 89% and 91% respectively (figures 8 and 9). Consequently these reduction in contaminants proved that anaerobic process of digestion was an operational technique for removal of organic pollution. Some researchers reported the same results (Bolzonella et al., 2005; Álvarez et al., 2006; Wang et al., 2006). Another criterion for proving the removal of organic pollutants was reduction of total solids (TS), where the drop approached 88.23% (figure 10). Some researcher’s reports approached the same drop (Hutnan et al., 2006; Linke, 2006; Raposo et al., 2009). Therefore it was possible to conclude that anaerobic digestion necessary showed decrease or reduction of organic pollutants rates because of the transformation of organic substances into biogas and accordingly led to the drop of chemical oxygen demand (COD). This could be explained in figure 11 by the comparison of the two techniques during the anaerobic digestion process. That means the chemical oxygen demand (COD) drop should be tailed essentially by Total solids drop (TS).Microbial activity: Figure 11 showed the microbial variation during anaerobic digestion. The total micro flora (total germs) declined from 1.8x107 (before starting the process of digestion) to1.1x105 germs/mL (after completion of 30 days of digestion). Moreover figure 12 obviously explained what was running during the process of digestion in the reactor, microbial species vanishing after the 30 days such as streptococci and Escherichia coli. Some researchers reports explained that there was some sort of relationship between physicochemical and the biological parameters of micro flora with total solid (TS). figure 13 described obviously this relationship of the drop of micro flora which go along with total solids reduction. This intended that consumption and a declining in the mass residue of organic materials created at the termination of digestion was the outcome of the transformation of organic materials into biological gas and also the sum of microorganism reduction. This attained result proved that the process of anaerobic digestion was a good process for decontamination (Deng et al., 2006; Perez et al., 2006; Davidsson et al., 2007).CONCLUSIONSoba sludge’s municipal station carried in this research paper demonstrated operative for biological gas production (biogas). During the first five days, breakdown of organic materials and the formation of volatile acids were started. Volatile fatty acids increased up to 1400 mill equivalents per liter (meq/L) in the first ten days, then started to decline in after the tenth day this owing to intake by bacteria which would resemble to acetogenesis stage. The biogas production lasted until the 21th day then starting decreasing till the last day (30 day) this due to instability of the culture medium of fermentation which became completely poor. COD and BOD showed a significant reduction of 89% and 91% respectively. 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Biogas (methane) production from batch anaerobic digesters containing varying concentration of sugar industry wastewater sludge as inoculums and organic fruit and vegetable market solid waste as a substrate was experimentally studied in this research. It was observed that biogas production was optimized with batch anaerobic digestion of fruit and vegetable solid waste. It was carried out for 60 days at room temperature with untreated sugar industry wastewater sludge as an inoculums with the varying concentration 10%, 20% and 30% of the working volume (Weight) of substrate. The performance of reactors was evaluated by measuring the daily biogas production at the room temperature and pH was maintained in the range of 6.8 to7.3 respectively. The maximum cumulative methane production is 597.66 ml/gVS. The biogas yields at the end of the 60days total cumulative biogas for R1, R2 and R3 was obtained as 382.48ml/gVS, 552.66ml/gVS and 597.66ml/gVS respectively from the reactors. At the end of the 60 days total cumulative biogas for Rc(control) was obtained as 196.85ml/gVS. It was observed that the methane content of the biogas generated from the reactors was in the range of 47–56% in control reactor and that forR1, R2and R3 were 56-61%, 60-67% and 65-74% respectively.

Objective This study is to investigate the changes of trace elements (Cu, Fe, Zn, Se, Mg) in serum and skeletal muscle of rats after skeletal muscle injury induced by downhill running, and to find out the change regularity of trace elements in the body after exercise injury. To provide experimental basis for how to use trace elements supplements reasonably. Methods Fifty-four healthy male Sprague-Dawley rats aged 8 weeks were randomly divided into two groups: control group (C, N=6) and exercise group (E, N=48, include: 0 h group, 6 h group, 12 h group, 24 h group, 48 h group, 72 h group, 1- week group and 2- week group). The rats in exercise groups run down a 16°incline at 16m/min for 90 minutes. At the end of the exercise, the rats were killed at 0 h, 6 h, 12 h, 24 h, 48 h, 72 h, 1 week and 2 weeks, respectively. The serum was got from the inferior vena cava blood and diluted by 1% nitric acid. The muscle was got from the right side of the rat's sural which were digested by concentrated nitric acid and 30% hydrogen peroxide in 75℃water bath for 20mins. The content of trace elements in muscle and serum were measured by inductively coupled plasma atomic emission spectrometry (ICP-MS). All the data are analyzed and processed by SPSS22.0 statistical software. Results (1) The contents of trace elements in serum showed: Cu, Zn, Mg, Se decreased immediately after exercise, but the Cu still increased to reach a peak at 24h after decreasing, and after 2 weeks the content of Cu was slightly lower than pre-exercise level. However, the content of Zn did not elevate again, it continued declined to the lowest at 24h which was significantly lower than control group (P < 0.05). And after 2 weeks, Zn did not return to the pre-exercise level. The changes of Mg, Se in serum was not statistically significant. There is no difference between 0h and control groups in content of Fe, after that Fe decreased continually and appeared the least value at 24h, the differences between immediate group and control group were statistically significant (P < 0.05). Fe returned to the pre-exercise level after 2 weeks. (2) The contents of trace elements in muscle showed: Most of trace elements increased to the maximum level at 6 h, after that Mg, Fe, Cu decreased to the lowest value at 72 h which were significant lower than 0h group or 6h group (P < 0. 05). ALL the trace elements were lower than pre-exercise level. There was no statistical difference in the content of Se in muscle. Conclusions (1) The different changes of trace elements in skeletal muscle and serum after exercise injury may be due to the redistribution of trace elements caused by the body adaptability. (2) The most obviously changes of trace element in serum and muscle are Cu and Zn. Both of them did not return to the pre-exercise level after 2 weeks, it suggests that the supplement include Cu and Zn may play an important role in recovering after exercise-induced injury.