A study of A2/O process in El-Berka WWTP by replacing the anaerobic selector with UASB and adopting a hybrid system in the oxic zone

ABSTRACT

A multistage system comprising an upflow anaerobic sludge blanket (UASB) followed by anoxic unit and then oxic activated sludge (AS) with biofilm is studied in El-Berka WWTP, Egypt. Different organic loading wastewaters of chemical oxygen demand (COD) less than 500 mg/L till 3000 mg/L are tested during the study. The hydraulic retention time (HRT) varies for each loading from 7.5 to 10 to 15 h. The UASB reactor accomplishes the removal efficiency of 50%–70% of influent COD. The overall system performs the removal efficiency of 95% of influent COD and NH₄-N. Also, the results are verified by a modified mathematical model.     

城市污水自养脱氮系统中有机物与磷的回收

厌氧氨氧化的发现使开发低能耗城市污水处理技术成为可能,可通过生物吸附实现污水能源与资源的回收。强化除磷系统污泥龄(SRT)仅为2 d,系统抗冲击性强,污泥沉降性良好,污泥体积指数(SVI)低于50,可为自养脱氮系统提供稳定的进水,但系统污泥碳含量仅为37%。将反应器内好氧水力停留时间(HRT)降至 40 min后,实现有机物去除序批式反应器(SBR)的稳定运行,厌氧段COD去除率占总COD去除率的93.8%,这表明系统对有机物的去除主要为生物吸附作用,同时污泥碳含量提升至48%。由于异养菌对有机物的消耗利用与除磷菌的吸磷过程同时进行,若试验废水C/P比较低,可降低系统水力停留时间、提升碳的回收率并辅助少量的化学除磷手段,对系统厌氧搅拌时间、曝气时间及污泥龄进行优化,从而实现C与P的高效回收。     

Effect of hydraulic retention time and temperature on submerged membrane bioreactor (SMBR) performance

Water shortages and strict environmental provisions necessitate wastewater renovation using various wastewater treatment methods, among which applications of submerged membrane bioreactors (SMBRs) are rapidly increasing due to their advantages such as high loading capacity and quality of effluent. In this work, the effect of hydraulic retention time (HRT 8, 10 and 12 h) and temperature (25, 30 and 35°C) on membrane fouling and sludge production was investigated in a 5-Liter SMBR equipped with immersed PVDF hollow fiber membrane module. Phenolic synthetic wastewater and acclimatized activated sludge with phenol during a 2-month period were used as toxic and microbial sources, respectively. Results showed that by increasing HRT membrane fouling decreases, while excellent treatment performance of over 99.5% phenol and 95% COD removals was achieved at all HRTs. Therefore, HRT=8 h corresponding to the highest effluent flow rate of 12 L/m²·h was used to investigate the effect of temperature, resulting in phenol and COD removals of higher than 99 and 96%, respectively, at all temperatures. Membrane fouling occurred at 12, 5 and 3 days for 25, 30 and 35 °C, respectively. Additionally, the effect of HRT and temperature on mixed liquor volatile suspended solid (MLVSS) as a measure of biomass was examined. MLVSS concentration showed decreases with increasing HRT and temperature. Overall, it was shown that SMBR can be used to efficiently treat phenolic wastewater at a range of flow rates and temperatures, among which HRT=8 h and T=25 °C are the preferred operating conditions, resulting in high flow rate and low membrane fouling.     

SBR降解处理高浓度工业油脂加工废水的微生物学分析

小试研究了采用规模为12L的间歇式活性污泥法(SBR)生物反应器处理高浓度工业油脂废水,并分析了油脂废水降解过程中污泥体积指数、容积负荷、污泥负荷等的微生物学特性变化。研究结果表明:该反应器在水力停留时间(HRT)为10h,控制适当污泥浓度时,出水稳定,水质良好,COD<100mg/L、油脂<30mg/L、SS<100mg/L,且无色、无味,符合油脂行业颁布的废水水质标准。     

新型厌氧反应器COD去除影响因素研究

以模拟高浓度有机废水为研究对象,采用新型厌氧反应器对COD去除影响因素进行了为期4个月的试验研究,考察了污泥负荷、水力停留时间(HRT)、容积负荷、进水COD、VFA、出水SS等因素对COD去除的影响。结果表明,影响COD去除的主要因素是污泥负荷、HRT和容积负荷,次要因素是进水COD、VFA和出水SS,当反应器内COD污泥负荷在0.297 2～0.464 7 kg.kg-1.d-1之间、HRT=7 h时,COD的去除效率维持在72%～90%。     

Treatment of a combined dairy and domestic wastewater in an up-flow anaerobic sludge blanket (UASB) reactor followed by activated sludge (AS system)

The feasibility of using an up-flow anaerobic sludge blanket (UASB) reactor followed by activated sludge (AS system) for the treatment of wastewater discharged from dairy factory was explored. The UASB reactor was operated at a hydraulic retention time (HRT) of 24 h and organic loading rates (OLRs) ranging from 1.9 to 4.4 kgCOD/m³.d. The average total chemical oxygen demand (COD_total) and total biological oxygen demand (BOD_5total) concentrations of the UASB reactor effluent were 1385 and 576 mg/l, corresponding to percentage removal of 69% and 79%, respectively. Total suspended solids (TSS) and volatile suspended solids (VSS) removal averaged above 72% and 75%, respectively. Residual phosphorous and oil and grease concentrations of the UASB reactor effluent were 8.2 and 44 mg/l, corresponding to percentage removal values of 63% and 83%, respectively. This good performance could be attributed to the relatively long sludge residence time (SRT = 76 d) imposed to the reactor. Total and faecal coliform counts were reduced in the treated effluent by a value of 1.07 and 0.9 log₁₀, respectively. The net sludge yield coefficient was found to be 0.2 g VSS per g COD_total removed per day, corresponding to 20% of the total influent COD imposed to the UASB reactor. The volatile solids / total solids (VS/TS) ratio of 0.66 of excess sludge revealed its good quality. Preliminary batch experiments of the AS system treating UASB reactor effluent indicated first-order removal kinetics between total organic carbon (TOC) and contact time. The TOC removal reached 80%, resulting in only 47 mg/l in the final effluent at a HRT of 2.0 h. Accordingly, the AS system was operated at a HRT of 2.0 h. The system achieved a substantial reduction of COD_total, BOD_{5 total}, TSS and oil and grease resulting effluent quality with residual values of only 35.0, 7.0, 14.0 and 2.8 mg/l, respectively. The geometric mean of total and faecal coliform counts was reduced by a value of 1.28 and 1.64 log₁₀, respectively. Based on these results, it is recommended to use of an integrated system consisting of a UASB reactor followed by the AS system for the treatment of a combined dairy and domestic wastewater to produce a good effluent quality complying with the standards for discharge into agricultural drains.     

Simultaneous organic and nutrient removal from municipal wastewater by BSACNR process

Biological nutrient removal was investigated under a biological synthetic activated ceramic nutrient removal (BSACNR) process. Tests were made to establish whether organic compounds and nutrients (N, P) from municipal wastewater were eliminated effectively in a lab-scale BSACNR process by increasing the hydraulic retention time (HRT) from 4 hr to 10 hr. In the system, synthetic activated ceramic (SAC) media were packed in each reactor for attached growth of both nitrifying bacteria and denitrifying bacteria; the sludge of the clarifier was returned to the anaerobic reactor to release phosphate. In this configuration, nitrification, denitrification and phosphorus removal could be performed at their respective conditions. The influent was synthetic wastewater, and the mean concentration of COD, NH⁺ ₄ -N and T-P in the influent was about 200 mg/L, 20 mg/L and 8 mg/L, respectively. At a total HRT of the system of 4-10 hr, the system worked successfully obtaining the removal of COD, NH⁺ ₄-N, T-N and T-P: 90.5-97.5%, 72.9-94.4%, 56.5-73.7% and 36.0-61.1%, respectively. The results of this research show that a biological synthetic activated ceramic nutrient removal (BSACNR) process packed with SAC media could be applicable for treatment of organic and nutrient from municipal wastewater.     

一体式MBR系统对印染废水有机物去除效果分析

采用一体式MBR系统对模拟印染废水有机物的去除效果进行了深入的研究。通过改变水力停留时间(HRT)、污泥负荷、容积负荷、曝气量等运行参数,一体式MBR系统对COD的去除率可达到90%,且COD去除率在一定程度内随着污泥负荷的增加而增加,容积负荷基本上随着水力停留时间的延长而降低。     

Application of A2O moving-bed biofilm reactors for textile dyeing wastewater treatment

A three-stage pilot-scale moving-bed biofilm reactor (MBBRs, anaerobic-anaerobic-aerobic in series) was investigated to treat textile dyeing wastewater. Each reactor was filled with 20% (v/v) of polyurethane-activated carbon (PU-AC) carrier for biological treatment. To determine the optimum operating conditions of MBBRs, the effect of PUAC carrier, its packing percentage (v/v%) and pH control on COD removal were analyzed by batch experiments. The MBBRs were inoculated with activated sludge obtained from a local dyeing wastewater treatment plant. The MBBR process removed 86% of COD and 50% of color (influent COD=608 mg/L and color=553 PtCo unit) using relatively low MLSS concentration (average 3,000 mg/L in biomass attached to PU-AC carrier) and hydraulic retention time (HRT=44 hr). The MBBR process showed a promising potential for dyeing wastewater treatment.     

Biological treatment of saline wastewater using a salt-tolerant microorganism

Biological aerobic treatment of saline wastewater provides the material of this study. A salt-tolerant microorganism (Staphylococcus xylosus) was isolated from a vegetable pickled plant containing about 7.2% salt. Selection, identification and characterization of the microorganism were carried out. The isolated microorganism was used as inoculum for biodegradation. An activated sludge reactor operated in a fed-batch mode was used for the treatment of synthetic saline wastewater using three different microbial cultures namely: activated sludge (100%), a mixture of Staphylococcus supplement by activated sludge (1:1) and pure S. xylosus (100%) at different salt concentrations ranging from 0.5 to 3% NaCl. The results obtained showed that at low NaCl concentration (1%), the removal efficiency of chemical oxygen demand (COD) using different microbial cultures were almost the same (80-90%). However, increasing the NaCl concentration to 2% and using Staphylococcus-supplemented mixture by activated sludge and S. xylosus alone improved the treatment performance as indicated by COD removal rates which reached 91% and 93.4%, respectively, while the system performance started to deteriorate when activated bacterial culture was used alone (74%). Furthermore, the increase in NaCl concentration up to 3% and with the inclusion of Staphylococcus-supplemented mixture by activated sludge increased the COD removal to 93%, while the use of S. xylosus alone further improved the COD removal rate up to 94%. Also, the use of S. xylosus alone proved to be capable for biological treatment of a real case study of a vegetable pickled wastewater containing 7.2% salinity; the removal efficiency of COD reached 88% at this very high concentration of NaCl.     

微氧厌氧处理糖蜜酒精废水的限制因素

研究了膨胀颗粒污泥床(EGSB)在微氧厌氧条件下处理糖蜜酒精废液的效果,确定最佳的氧化还原电位(ORP)、回流比及水力停留时间(HRT)。结果表明ORP为-440 mv、回流比为3∶1、HRT为15 h时,微氧条件下EGSB生物处理系统的处理效果为最佳。在此条件下,COD、SO24-的去除率分别为73.4%、61.3%,出水浓度分别为1 600、185 mg/L。     

Investigation of municipal and olive mill wastewater co‐treatment in activated sludge–powdered activated carbon (AS‐PAC) systems

BACKGROUND: The purpose of this study was to investigate the co‐treatment of olive‐mill wastewater (OMW) and municipal wastewater in activated sludge systems operating in the absence and presence of different adsorbent materials and to study the role of sorption and biodegradation in total phenols removal. RESULTS: Batch experiments were initially conducted to investigate total phenols' adsorption capacity on activated sludge (AS), olive pomace (OP) and powdered activated carbon (PAC). According to the results, PAC presented the best adsorption capacity. Three sequencing batch reactors (SBRs) were also operated, treating municipal wastewater and different amounts of OMW. The first SBR contained AS (AS‐System), the second AS and OP (AS‐OP System) and the third AS and PAC (AS‐PAC System). All SBRs operated sufficiently in the presence of 1% v/v OMW, achieving mean COD and total phenols removal efficiency higher than 86% and 85%, respectively, and satisfactory settling capacity. Increase of OMW concentration to 5% v/v affected the performance of SBRs, resulting in mean COD removal efficiencies that ranged between 61% (AS‐OP System) and 80% (AS‐PAC System). CONCLUSION: Among the SBRs used, the AS‐PAC System operated with highest performance in the presence of 1 and 2.5% v/v OMW, and showed better stability in the presence of 5% v/v OMW. Calculation of total phenols mass flux revealed that biodegradation was the principal mechanism of their removal. The highest values of mean biotransformation rates were calculated for the AS‐PAC System and ranged between 2.0 and 40.6 d^?1 for different experimental phases. Copyright © 2012 Society of Chemical Industry     

Potential for reuse of high cellulose containing wastewater after membrane bioreactor treatment

It is difficult to adequately treat wastewater with a high cellulose content with the traditional anaerobic and aerobic activated sludge processes. In this study we used microfiltration (MF) and reverse osmosis (RO) membranes combined with an anaerobic or aerobic activated sludge process to treat high cellulose containing wastewater for different hydraulic retention times (HRTs). The potential target applications for reuse of the treated wastewater are also compared. Six bioreactors, which were configured as anaerobic sequencing batch reactor (ANSBR), aerobic sequencing batch reactor (ASBR), aerobic membrane bioreactor (AMBR), AMBR plus RO (AMBR/RO), anaerobic activated sludge plus aerobic MBR (AOMBR), and AOMBR plus RO (AOMBR/RO), was operated in this study. The experiment results showed that, as expected, no effluents from the ASBR or the ANSBR could meet the Taiwan EPA criteria for effluent and wastewater reuse, no matter what the HRT was. However when the HRT was 12 h or more, the effluent from the AMBR and AOMBR processes did meet the criteria for effluent, but still did not meet the treated wastewater reuse criteria , primarily due to the color, total alkalinity, and total dissolved solid parameters. Finally, the effluents from the AMBR/RO and AOMBR/RO processes did meet the Taiwan criteria for both effluent and treated wastewater reuse when the HRT for the AOMBR/RO and AMBR/RO processes was equal to or longer than 12 h and 8 h, respectively. For the HRT of 4 h for both the AOMBR/RO and AMBR/RO process, and an HRT of 8 h for the AOMBR/RO process, neither the effluent criteria nor the treated wastewater reuse criteria were met.     

好氧颗粒污泥培养方法及其厌氧化研究

以葡萄糖为底物,普通絮状活性污泥为接种污泥,30目以上4 0目以下木炭颗粒为载体,在类似SBR反应器中提高反应器COD负荷、减少沉淀时间,不断洗出细小分散污泥和絮状污泥,使微生物在木炭颗粒表面附着生长,当COD负荷为3 2kg/ (m3 ·d) ,沉降时间为2 0min时,反应器污泥床中活性污泥实现颗粒化。此阶段下,污泥体积指数SVI为1 8mL/g ,MLSS 90 0 0mg/L。好氧颗粒污泥直径大多2 . 0～2 . 5mm。在好氧颗粒污泥厌氧化研究中,控制温度在30℃,pH值在7 . 5～8. 0之间,停留时间为2 4h ,COD负荷从2kg/ (m3 ·d)增加至4kg/ (m3 ·d) ,COD去除率从4 5 %增加到6 6% ,好氧颗粒污泥在厌氧条件下具有了有机物分解和去除的效果,可以认为转变成了厌氧颗粒污泥。     

UASB反应器处理活性黑KN-B废水的研究

采用UASB反应器处理活性黑KN—B废水,研究了水力停留时间（HRT）、碳源组成及浓度等因素对废水处理效果的影响,考察了反应器对该废水可生化性降解的作用。试验结果表明：反应器的最佳HRT为24h,当HRT小于24h时．废水的COD去除率显著降低,而BOD,的去除率不受影响,稳定在90％。在不同葡萄糖和蛋白胨的碳源组合下．碳源含量高于2000mg／L时,废水处理效果差别不大;而碳源含量过低,低于2000mg／L时,COD去除率将明显下降,不利于对废水的处理：而BOD;的去除率受进水碳源组成的影响较小。在试验的各种条件下,UASB反应器的活性污泥都能够有效处理500mg／L的高浓度活性黑KN—B废水,去除率稳定在90％以上。     

Performance of a ZVI‐UASB reactor for azo dye wastewater treatment

BACKGROUND: Zero valent iron (ZVI) is expected to be helpful for creating an enhanced anaerobic environment that might improve the performance of the anaerobic process. Based on this idea, a ZVI packed upflow anaerobic sludge blanket reactor (ZVI‐UASB) was developed to enhance azo dye wastewater treatment. RESULTS: The ZVI‐UASB reactor was less influenced by a decrease in the operational temperature from 35 °C to 25 °C than a reference UASB reactor that did not contain ZVI. In addition, chemical oxygen demand (COD) and color removal efficiencies of the ZVI‐UASB reactor at an HRT of 12 h exceeded those of the reference reactor at an HRT of 24 h. The hydraulic circulation in the ZVI bed enhanced the function of ZVI so that it improved the COD and color removal efficiencies. Moreover, fluorescence in situ hybridization experiments revealed that the abundance of Archaea in the sludge of the ZVI bed was significantly higher than that at the reactor bottom, which made the reactor capable of greater COD removal under low temperature and short HRT conditions. CONCLUSION: This ZVI‐UASB reactor could adapt well to changes in the operational conditions during wastewater treatment. Copyright © 2010 Society of Chemical Industry     

Anaerobic/aerobic sequential treatment of a cotton textile mill wastewater

The treatment of a wastewater taken from a cotton textile mill was investigated using an anaerobic/aerobic sequential system during an operational period of 87 days. The process units consisted of an upflow anaerobic sludge blanket (UASB) reactor and a continuous stirred tank reactor (CSTR). Wastewater characterization was performed before feeding the reactor system. Glucose‐COD, and azo dyes were added to the textile wastewater for comparative purposes in the final period of operation. The pH values in the effluent of the UASB reactor were suitable for optimal anaerobic treatment in all runs. The biodegradable part of the COD in wastewater was removed effectively, with the anaerobic stage improving the biodegradability of wastewater entering the aerobic stage. The UASB reactor permitted COD and color removals of 9–51% and 46–55%, respectively, at a hydraulic retention time (HRT) of 30 h. COD removal efficiencies were between 40 and 85% and color removal efficiencies were 39–81% in normal and artificially‐colored wastewaters at a total HRT of 5.75 days in the UASB/CSTR reactor system. Benzidine produced from the cleavage of azo bond in the anaerobic stage was effectively removed in the aerobic stage, and was identified by comparison of its HPLC spectrum with that of an authentic specimen. Copyright © 2004 Society of Chemical Industry     

Membrane bioreactor for treatment of pharmaceutical wastewater containing acetaminophen

Treatment of pharmaceutical wastewater is a real challenge for wastewater engineers. In this study, a pilot-scale system including an external loop airlift membrane bioreactor (ELAMBR) was applied for treatment of a synthetic pharmaceutical wastewater. The performance of this system was evaluated in removal of acetaminophen as the main pollutant of a pharmaceutical wastewater. A conventional activated sludge (CAS process) laboratory system was used in parallel with this system to compare both systems in regard to their ability for acetaminophen removal. The performance of the ELAMBR system was monitored for approximately one month to investigate the long-term operational stability of the system and possible effects of solids retention time on the efficiency of removal of acetaminophen. The removal efficiency was significantly higher in the ELAMBR system than the CAS process. 100% of the acetaminophen was removed after 2 days in this system. The results also showed that initial concentration of acetaminophen, chemical oxygen demand (COD) and mixed liquid suspended solids (MLSS) are the most effective parameters in removal of a pollutant such as acetaminophen. This study demonstrates the usefulness of ELAMBR system for pharmaceutical wastewater treatment with the advantages such as: (i) simple operation and maintenance, (ii) efficient removal of pharmaceutical pollutant and COD and (iii) low-energy consumption.     

污泥负荷对UBF处理农村污水的影响

研究了在常温条件下不同污泥负荷对UBF反应器污水处理性能的影响。结果表明在进水浓度为1200 mg/L、水力停留时间（HRT）为10 h、污泥负荷为0．59 kg COD/kg MLSS·d时,UBF对COD的去除效果最佳,达80．14％;在污泥负荷达到1．01 kg COD/kg MLSS·d之前,污泥中生物量比例随着污泥负荷的增加而增加,MLVSS/MLSS值可达0．89;UBF反应器对污水可生化性有较好的改善效果,BOD5/CODCr比值增幅可达28．52％,且低污泥负荷更有利于污水可生化性的改善。     

高效厌氧反应器处理中药提取废水中试研究

应用新型高效厌氧反应器处理中药提取废水。从有机物去除率、产气效率及颗粒污泥增殖等方面评估了系统的运行效果。结果表明,经过2个多月的启动运行,该系统的COD去除率平均达到98%以上,出水COD500 mg/L,COD容积负荷高达25 kg/(m~3·d),甲烷产率为0.31 L/g COD。水力停留时间为12~24 h,系统运行稳定,抗冲击负荷能力较强。启动过程中,颗粒污泥粒径增大到1.8~2.5 mm。