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1.
The investigation was carried out on laboratory scale to assess the feasibility of upflow anaerobic sludge blanket reactor system as a pretreatment for hydrogenated vegetable oil industry wastewater with recourse to energy recovery. The reactor system operated at 35°C, resulted in COD removal efficiency in the range 98.9–80.1% at organic loading varying in the range 1.33–10 kgCOD/m3 day. The specific methane yield varied from 0.295–0.345 m3CH4/kgCODr. Hydraulic retention time, substrate concentrations, pH, and temperature were also varied to study the influence of operating parameters on reactor performance. The methane content decreased with increase in substrate loading rate, and varied from 53–66.7% under varying operating conditions. Impulse loading studies in terms of hydraulic, organic, and pH though resulted in destabilization of the reactor; however, the reactor rapidly achieved stable performance after steady operation.  相似文献   

2.
Changes in the acetoclastic methanogenic activity in the effluentfrom an upflow anaerobic filter (UFAF) were studied throughout a 36 week operating period. The UFAF formed the second phase of a two-phase laboratory-scale anaerobic treatment system. TheSpecific Methanogenic Activity (SMA) test was used to measurethe acetoclastic methanogenic activity of the biomass washed outfrom the UFAF. Throughout the operating period, the SMA testswere carried out at different organic loading rates (OLR) up to6.7 kg COD m-3 d-1 and upflow velocities (UV), 5 m d-1 and 15 m d-1. The results showed that thebiomass washed out from the UFAF consisted of up to 55%(considered as a draft value) acetoclastic methanogens producing550 mI CH4 g-1 VSS d-1. This high acetoclasticmethanogenic activity measured in the effluent might have beendue to the existence of Methanosaeta (formerly Methanothrix) species. Towards the end of operation,Epifluorescence Microscopic examinations in the effluent revealedthat Methanococcus species were the most dominant groupfollowed by medium rods and short rods, filaments and long rodsand the least dominant Methanosarcina species. Theperformance of the UFAF was not adversely affected by the loss ofthe active biomass and changes in their composition. The UFAFsystem achieved over 85% COD removal efficiency at thehighest OLR of 6.7 kg COD m-3 d-1 and UV of 15 m d-1. Throughout most of the operation, methane yield rangedfrom 0.28–035 m3 CH4 kg-1 CODremoved.  相似文献   

3.
Laboratory-scale models consisting of a simple upflow anaerobic sludge blanket reactor (UASBR) and an upflow anaerobic filter (UAF) in series were subjected to organic loadings of 0.19 to 0.55 kg COD m?3 d?1 at 20°C. COD and SS removals were 95 to 98% and 98 to 99%, respectively. Biogas produced by the system amounted to 0.31 to 0.32 m3 CH4 kg?1 COD removed. The UASBR was more stable than the UAF in performance. No sign of deterioration in final effluent quality was observed during 420 days of operation under low loading.  相似文献   

4.
Simultaneous power generation and fecal wastewater treatment were investigated using a combined ABR-MFC-MEC system (anaerobic baffled reactor-microbial fuel cell-microbial electrolysis cell). The installation of multi-stage baffles can benefit retaining the suspended solids in the system and help separate the hydrolysis-acidification and the methanogen processes. The efficiencies of the nitrification-denitrification process were improved because of the weak current generation by coupling the microbial electrochemical device (MFC-MEC) with the ABR unit. Maximum removal rates for chemical oxygen demand (COD) and ammonia nitrogen (NH4 +-N) were 1.35 ± 0.05 kg COD/m3/day and 85.0 ± 0.4 g NH4 +-N/m3/day, respectively, while 45% of methane (CH4), 9% of carbon dioxide (CO2), and 45% of nitrogen gas (N2) contents in volume ratio were found in the collected gas phase. An average surplus output voltage of 452.5 ± 10.5 mV could be achieved from the combined system, when the initial COD concentration was 1500.0 ± 20.0 mg/L and the initial NH4 +-N concentration was 110.0 ± 5.0 mg/L, while the effluent COD could reach 50.0 mg/L with an HRT of 48 h. The combined process has the potential to treat fecal wastewater efficiently with nearly zero energy input and a fair bio-fuel production.  相似文献   

5.
Static granular bed reactor (SGBR) and upflow anaerobic sludge blanket (UASB) reactor were demonstrated at mesophilic condition for the treatment of pulp and paper mill wastewater. The hydraulic retention times (HRTs) were varied from 4 to 24 h following 29-day start-up period. The overall chemical oxygen demand (COD) removal efficiency of the SGBR was higher than the UASB during this study. At 4 h HRT, the COD removal was greater than 70 % for the SGBR and 60 % for the UASB. Biomass yield and volatile fatty acids concentration of SGBR were slightly less than UASB at organic loading rates ranging from 1.2 to 5.1 kg/m3/day. The results indicated that the SGBR system can be considered a viable alternative system for anaerobic treatment for pulp and paper wastewater.  相似文献   

6.
Ong  S. L.  Liu  Y.  Lee  L. Y.  Hu  J. Y.  Ng  W. J. 《Water, air, and soil pollution》2004,157(1-4):245-256
A lab-scale novel biofilm reactor system, Ultra-Compact Biofilm Reactor (UCBR), was studied to investigate its performance and operational characteristics for domestic sewage treatment. The reactor was operated at four different hydraulic retention times, namely, 90, 60, 30 and 15 min. The operating ranges of volumetric loading rates in terms of COD, BOD5, NH+ 4-N and TKN were 5.6-62.1 kg COD/m3 d, 2.6-32.5 BOD5/m3 d, 0.6-3.2 kg NH+ 4-N/m3 d and 0.82-6.2 kg TKN/m3 d, respectively. The COD, BOD5 and NH+ 4-N removal efficiencies at 90-min hydraulic retention time (HRT) and 60-min HRT could exceed 80%, 90% and 99%, respectively. The corresponding maximum biomass concentrations were 12.0 g/L and 15.0 g/L at 90-min HRT and 60-min HRT, respectively. At 30-min HRT, the biomass concentration increased to a maximum of 24.0 g/L. However, COD and BOD5 removal efficiencies decreased to 75% and 80%, respectively, while the NH+ 4-N nitrification efficiency decreased to only 25% to 30%. These observations suggested that high biomass concentration alone was not sufficient to provide a high removal capacity in a UCBR. Further reduction in HRT to 15 min led to an excessive biomass decline from 22.5 g/L to 4.0 g/L. On the whole, the UCBR was able to sustain COD removal and NH+ 4-N conversion of up to 5.96-18.70 kg COD/m3 d and 0.73-1.00 kg NH+ 4-N/m3 d, respectively.  相似文献   

7.
A batch anaerobic composting process was investigated to evaluate the potential for biogas recovery from animal manure under the worst scenario of high initial solids and non-well adapted microorganisms. The effects of composting time and initial total solids content on biogas recovery and reduction of solids during anaerobic digestion of swine, poultry and beef manure were studied. Volatile solids reductions averaged 10% or less over a 30-day period for all initial solids contents, which was considerably lower than expected. Reductions in VS increased slightly as initial solids content in the reactor decreased. Reductions in COD were somewhat higher than for VS. The pH values were fairly stable during the composting experiments and within the range suitable for anaerobic digestion. Decreases in TKN and ammonia nitrogen during the process were insignificant, and greater decreases were observed for lower initial solids content in the reactors. Cumulative biogas production increased with decreasing solids content in the reactor for all types of manure. For the lowest initial solids contents (12-14%), swine manure produced more biogas, but at the higher initial solids contents there was little difference among the manure types. Biogas yields were about 0.5 m3/kg VS consumed for the lowest solids contents; however, yields were only about 0.2 m3/kg VS consumed for the higher initial solids. Methane content of the biogas samples averaged 49%. Based on these results, it appears that adapting microbial populations in the high solids feedstock may obtain reasonable biogas production rates and VS reduction during anaerobic digestion. Although some differences in results among the three types of manure were noted, they were not large and likely would not be significant with adapted microbial populations.  相似文献   

8.
A vertically moving biofilm system (VMBS) was developed to treat wastewater. In this system, the biofilm grows on a biofilm module consisting of plastic media that is vertically and repeatedly moved up into the air and down into the water. The objectives of this study were to investigate the oxygen transfer efficiency and industrial wastewater treatment performance of the VMBS. The oxygen transfer coefficient (K L a) depended on the movement frequency (n) of the biofilm module and was proportional to n 1.67. K L a values measured were within the range of 0.0001 to 0.0027 s-1. The VMBS exhibited good carbonaceous removal when treating industrial wastewater produced in a factory manufacturing synthetic fibres. Removal efficiency of filtered chemical oxygen demand (COD) and biological oxygen demand (BOD5) was up to 93.2 and 97.9%, respectively. The volumetric removal rates of filtered COD and BOD5 reached 1320 g COD m-3 day-1 and 700 g BOD5 m-3 day-1. The areal organic removal rates, based on the surface area of the biofilm substrata, were 16 g BOD5 m-2 day-1 and 39 g COD m-2 day-1. No clogging occurred during the experiment. The mean areal biofilm mass increased with increasing the mean areal BOD5 removal rate. The new biofilm process has such advantages as high carbonaceous oxidation, energy saving, simpleconstruction and easy operation for industrial wastewater treatment.  相似文献   

9.
固定床厌氧反应器处理高浓度糖蜜废水   总被引：9，自引：4，他引：5  
为开发高效处理高浓度有机废水的厌氧沼气发酵技术,以活性炭纤维作为生物膜载体,在实验室规模上对固定床厌氧反应器处理高浓度糖蜜废水的运行性能进行了研究。初始进水COD为5 000 mg/L,水力停留时间（HRT）保持在2 d左右。在进水COD为47 000 mg/L以内时,相应的有机容积负荷（OLR,COD含量）达到21.38 kg/(m3×d),COD去除率保持在86%以上,沼气容积产气率为9.51 L /(L×d),甲烷容积产气率为6.46 L /(L×d);当OLR进一步从21.38 kg/(m3×d) 逐步升高到35.13、39.06、44.88 kg/(m3×d) 时,COD去除率从86.48%分别降低到74.40%,67.02% 和63.50%,相应的沼气容积产气率为13.71,13.98和11.44 L/(L×d),甲烷容积产气率为8.84,8.67和5.89 L/(L×d)。进水的pH值通常在3.5～5.6之间,OLR低于35.13 kg/(m3×d) 时,无需对pH值进行中和调节,出水的pH值自然维持在6.8～7.6的良好状态,超出此范围,则需加碱对进水的pH值作适当调节。最终进水COD高达78 600 mg/L,相应的OLR为44.88 kg/(m3×d)。在165 d的运行过程中污泥形成量小,没有发生堵塞现象,固定床厌氧反应器表现出高效的处理酸性高浓度有机废水和较强的抗负荷冲击的能力。  相似文献   

10.
Upflow anaerobic sludge blanket (UASB)reactors were used to treat municipal wastewater attemperatures of 6, 11, 15, 20 and 32 °C and athydraulic retention times (HRTs) ranging from 48 to 3 h overan operational period of approximately 860 days. The Monodmodel was used to evaluate substrate utilization. TheArrhenius model was used to calculate the activationenergies from which temperature coefficients weredetermined. It was found that the maximum specific substrateutilization rate constant (k) decreased from 0.387 d-1(at 32 °C) to 0.041 d-1 (at 6 °C). Thedecay rate constant (kd), yield coefficient (Yg),half velocity constant (Ks) and maximum specific growthrate (μm ) were also impacted by temperature in theUASB treatment of municipal wastewater.  相似文献   

11.
The effect of step-feed on biological ammonia nitrogen (NH3-N) removal in a rotating biological contactor (RBC) system consisting of two three-stage units (one control and one step-feed) treating synthetic wastewater was examined. The performance of the step-feedRBC was evaluated in comparison to a regularly fed RBC in terms of NH3-N removals and stage-dissolved oxygen (DO) conditions over a range of hydraulic and organic loading rates (HLR = 0.032 to 0.125 m3 m-2. d-1 and OLR = 11.03 to 111.6 g COD m-2. d-1). The results indicate that the step-feed unit showed better removal efficiency (%) at high HLR and ORL than the regularly fed control unit. Increasing the HLR and the OLR resulted in a decrease in DO in all the stages of the two units. However, DO values in the step-feed system were higher than those recorded for the control system. In addition, O2 limiting conditions (DO ≤ 2 mg l-1) and heavy growth of Beggiatoa were detected in stage 1 of the control unit at high loading rates.  相似文献   

12.
Hydroponics culture generates large amounts of wastewater that are highly concentrated in nitrate and phosphorus but contains almost no organic carbon. Constructed wetlands (CWs) have been proposed to treat this type of effluent, but little is known about the performance of these systems in treating hydroponic wastewater. In addition, obtaining satisfactory winter performances from CWs operated in cold climates remains a challenge, as biological pathways are often slowed down or inhibited. The main objective of this study was to assess the effect of plant species (Typha sp., Phragmites australis, and Phalaris arundinacea) and the addition of organic carbon on nutrient removal in winter. The experimental setup consisted of 16 subsurface flow CW mesocosms (1 m2, HRT of 3 days) fed with 30 L?d1 of synthetic hydroponics wastewater, with half of the mesocosms fed with an additional source of organic carbon (sucrose). Carbon addition had a significant impact on nitrate and phosphate removal, with removal means of 4.9 g m-2?d-1 of NO3-N and 0.5 g m-2 d-1 of PO4-P. Planted mesocosms were generally more efficient than unplanted controls. Furthermore, we found significant differences among plant treatments for NO3-N (highest removal with P. arundinacea) and COD (highest removal with P. australis/Typha sp.). Overall, planted wetlands with added organic carbon represent the best combination to treat hydroponics wastewater during the winter.  相似文献   

13.
This study analyzed global trends in the industrial use ofanaerobic wastewater treatment systems. Information on over 750anaerobic systems installed over the last two decades by three leading suppliers of anaerobic systems, namely ADI SystemsInc., Biothane Corporation, and Paques, showed exponential growthin the use of industrial anaerobic wastewater systemsinternationally up to the mid-1990s. After 1994, the number ofannual installations declined, and has been relatively constantover the last three years. The North American market was shown tobe relatively volatile, with no clear indication of futuregrowth, while the European market was found to be relativelymature. In North America, most of the anaerobic wastewatertreatment systems are serving breweries (26%), potato processingindustries (11%), or pulp and paper industries (9%). Ananalysis of the market history of the commercial anaerobic modelssuggests the phasing out of traditional UASB and fermentormodels, and the potential for growth of high-capacity and high-rate systems (>20 kg m-3 d-1) such as the BiothaneEGSB and the Paques Internal Circulation (IC) systems. Future efforts should focus on research into new designs for high-rate and high-capacity systems, and on the encouragement of economic incentivesfor industries implementing anaerobic wastewater treatmentsystems. A market study on other methods of wastewater treatment(e.g. aerobic treatment) is also recommended, to provide insightinto current economic trends in the area of environmental biotechnology.  相似文献   

14.
Abstract

Multi-soil-layering (MSL) system was designed for purifying domestic wastewater and for treating polluted river water. MSL system is typically comprised of layers of soil mixture blocks alternating with permeable layers. The permeable layer has roles of preventing clogging and to increasing the efficiency of infiltration of wastewater through the soil mixture blocks. In this study, the comparative efficiency of five MSL systems as a function of five permeable layer materials (zeolite, zeolitized perlite, perlite, gravel, and charcoal) was investigated. The MSL systems were constructed in 15 × 50 × 100 cm boxes where the soil mixture blocks contained sandy clay soil, kenaf + corncob, and iron scraps at a ratio of 6 : 1 : 1 by weight, respectively, and filled up in alternation with the permeable layer. The results indicated that all the MSL systems at loading rates of 96–346 L m?2 d?1 under nonaerated conditions were able to reduce the levels of COD (342–1,231 mg L?1), BOD5 (201–802 mg L?1), and soluble reactive phosphorus (SRP) (3.5–10.1 mg P L?1) at percentages of 79.0–98.1, 80.0–99.6, and 97.1–100%, respectively. The zeolite and the charcoal-based MSL systems under a 96–346 L m?2 d?1 loading rate effectively reduced the level of TN (41.4–65.5 mg N L?1) at percentages of 79.0–92.1 and 30.7–88.9%, respectively. In terms of prevention of clogging, the charcoal-based MSL system was the most effective, followed by the gravel and zeolite-based MSL. The apparent efficiency of pollutant removal, for zeolitized perlite, perlite, and gravel-based MSL systems was low. With an on-off aeration operation, the efficiency of the MSL systems in the reduction of the levels of COD, BOD5 , and SRP (hereafter reference to as “removal”) was significantly enhanced. Overall, the zeolite-based MSL system seemed to be more effective than the other MSL systems. However, if optimum aeration could be obtained, the removal efficiency of charcoal-based MSL system might be improved. Aeration at a rate of 64,000 L m?3 d?1 for 1 week alternating with 2 weeks of nonaeration enhanced the removal of COD, BOD5 , and SRP but not that of TN.  相似文献   

15.
Removal of nitrogen and phosphorus from a domestic wastewater using a sequencing batch reactor (SBR) was evaluated at solid retention times (SRTs) of 9.3, 13.8, and 18.3 days respectively. Oxygen uptake rates (OURs) and sludge settling characteristics were determined at each SRT investigated. COD removal, nitrification, denitrification, and phosphorus removal were accomplished by using the following operating cycle: 15-min unmixed fill; 2-hr mixed anaerobic period; 3-hr mixed aerobic period; 3-hr mixed anoxic period; 0.5-hr reaeration period; 1-hr settling period; 1-hr decant period; and a 1.5-hr idle period. Advanced wastewater treatment (AWT) standards of 5/5/3/1 mg L-1 for biochemical oxygen demand (BOD5), suspended solids (SS), total nitrogen (TN), and total phosphorus (TP) could not be achieved with the bench-scale SBR.  相似文献   

16.
A study of the anaerobic digestion of wastewater from the pressing of orange peel generated in orange juice production was carried out in a laboratory-scale completely stirred tank reactor at mesophilic temperature (37 degrees C). Prior to anaerobic treatment the raw wastewater was subjected to physicochemical treatment using aluminum sulfate as a flocculant and to pH reduction using a solution of sulfuric acid. The reactor was batch fed at COD loads of 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 g of COD. The process was very stable for all of the loads studied, with mean pH and alkalinity values of 7.5 and 3220 mg of CaCO3/L, respectively. The anaerobic digestion of this substrate was found to follow a first-order kinetic model, from which the specific rate constants for methane production, K(G), were determined. The K(G) values decreased considerably from 0.0672 to 0.0078 L/(g h) when the COD load increased from 1.5 to 5.0 g of COD, indicating an inhibition phenomenon in the system studied. The proposed model predicted the behavior of the reactor very accurately, showing deviations of <5% between the experimental and theoretical values of methane production. The methane yield coefficient was found to be 295 mL of CH4 STP/g of COD removed, whereas the mean biodegradability of the substrate (TOC) was 88.2%. A first-order kinetic model for substrate (TOC) consumption allowed determination of the specific rate constants for substrate uptake, K(C), which also decreased with increasing loading, confirming the above-mentioned inhibition process. Finally, the evolution of the individual volatile fatty acid concentrations (acetic, C2; propionic, C3; butyric, C4; isobutyric, iC4; valeric, C5; isovaleric, iC5; and caproic, C6) with digestion time for all loads used was also studied. The main acids generated were acetic and propionic for all loads studied, facilitating the conversion into methane.  相似文献   

17.
Chestnut agro-industrial companies consume a high volume of water for washing and processing fruit, generating a large volume of wastewater. This work studied the biodegradation of chestnut processing wastewater through aerobic assays, varying substrate, and biomass concentrations. In general, this wastewater presents a good biodegradability, especially in experiments with relatively low chemical oxygen demand (COD) (0.4 and 0.6?g O2 L?1) allowing a COD removal of 85?C90?%. The best results were obtained in the reactor initially loaded with 2?g?L?1 of biomass and 0.4 or 0.6?g O2 L?1 of COD. These experiments also showed high COD removal rates: 4.25 and 3.88?g COD g?1 volatile suspended solids (VSS) h?1, respectively. The sedimentation rate, evaluated for different initial values of biomass (1, 2, and 3?g?L?1), always presented higher values in the experiments with 2 and 3?g?L?1 of biomass, regardless of the initial COD value used. After comparing different kinetic models (Monod, Contois, and Haldane), it was observed that the Haldane inhibition model satisfactorily describes the COD biodegradation. AQUASIM software allowed calculating the kinetic constant ranges: K s, 1.59?C6.99?g COD L?1; ?? max, 25?C40?g COD g?1 VSS day?1; and K i values, 0.07?C0.11. These kinetic constants corresponds to maximum rates (??*) between 1.48 and 4.25?g COD g?1 VSS day?1 for substrate concentrations (S*) from 0.38 to 0.88?g COD L?1.  相似文献   

18.
Though engineered covers have been suggested for reducing landfill methane emissions via microbial methane oxidation, little is known about the covers' function at low temperature. This study aimed to determine the methane consumption rates of engineered soil columns at low temperature (4–12°C) and to identify soil characteristics that may enhance methane oxidation in the field. Engineered soils (30 cm thick) were mixtures of sewage sludge compost and de-inking waste, amended with sand (SDS soil) or bark chips (SDB soil). At 4–6°C, we achieved rates of 0.09 gCH4 kgTS?1d?1 (0.02 m3 m?2d?1) and 0.06 gCH4 kgTS?1d?1 (0.009 m3 m?2d?1) with SDS and SDB soils, respectively. With SDS, good movement and exchange of oxygen in porous soil moderated the slowdown of microbial activity so that the rate dropped only by half as temperature declined from 21–23°C to 4–6°C. In SDB, wet bark chips reduced the soil's air-filled porosity and intensified non-methanotrophic microbial activity, thus reducing the methane consumption rate at 4–6°C to one fourth of that at 21–23°C. In conclusion, soil characteristics such as air-filled porosity, water holding capacity, quantity and stabilization of organic amendments that affect the movement and exchange of oxygen are important variables in designing engineered covers for high methane oxidation at low temperature.  相似文献   

19.
Nitrogen is one of the two most important elements in the metabolism of aquatic ecosystems. At low concentrations it can limit primary productivity and when present at very high concentrations it can participate in the eutrophication process of these environments. The mechanism of nitrogen transport in sediments is almost unknown, nevertheless it is of vital importance for establishing mass balances in aquatic systems. In the study presented here, we assessed the nitrogen flux in sediments of the central part of tropical Lake Maracaibo, Venezuela, in particular with regard to dissolved oxygen concentrations. Experiments were performed under laboratoryconditions in a batch system, and at varying dissolved oxygenregimes (aerobic and anaerobic). Every two days, during 3 months,overlying water samples were taken to analyze nitrite, nitrate,ammonium and Kjeldahl total nitrogen. Average release rates oftotal nitrogen were 0.86 in aerobic, and 1.06 mmol N m-2 d-1 in anaerobic systems corresponding to 41.7% of total N input to the lake. The behavior of nitrogen was strongly influenced by nitrate concentrations under aerobic conditions, and by organic nitrogen under anaerobic conditions during the course of the experiment. A major trend for the release of organic nitrogen during anaerobic conditions, and of nitrate, during aerobic conditions, was observed. Also fluxes of NO3 -, NH4 +, organic N and Total N across the sediment-water interface were measured. In anaerobic conditions, which are predominant in the hypolimnetic cone of LakeMaracaibo, denitrification was estimated to be 0.02 mmol N m-2 d-1, which corresponds to 1.89% of the total N released from sediments.This is to our knowledge the first study of nitrogen fluxes insediments from Lake Maracaibo. The laboratory data presented herereflects conditions in the lake when major nutrients accumulation occurs.  相似文献   

20.
The starch manufacturing industrial units, such as sago mills,both in medium and large scale, suffer from inadequate treatment and disposal problems due to high concentration of suspended solids present in the sludge. A laboratory scale study was conducted to investigate the viability of anaerobic treatment of sago waste sludge, enriched in particulate organicmatter, using a fluidized bed reactor. The start-up of the reactor was carried out using a mixture of digested supernatantsewage sludge and cow dung slurry in different proportions. The effect of operating variables such as COD of the effluent, bed expansion, minimum fluidization velocity on efficiency oftreatment and recovery of biogas was investigated. The maximum efficiency of treatment was found to be 82% and the nitrogen enriched digested sludge was recommended for agricultural use. A kinetic model was developed for the degradation of particulate organic matter using the general kinetic equation [dS/dt = K HC SXC] which allowed for a more accurate mathematical representation of the hydrolysis process. Analysing data from a series of batch tests, the best fit value of C was found to be in the range 0.43 to 0.62.  相似文献   

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