Treatment of domestic sewage in a two-step anaerobic filter/anaerobic hybrid system at low temperature

The treatment of domestic sewage at low temperature of 13 degrees C was investigated in a two-step system consisting of an anaerobic filter (AF) +an anaerobic hybrid (AH) reactor operated at different hydraulic retention times (HRTs). The AF reactor was efficient in the removal of suspended COD, viz. 81%, 58% and 57% at an HRT of, respectively, 4, 2 and 3 h. For optimisation of the removal of suspended COD and dissolved COD, an HRT of 4 + 4 h is required for the AF + AH system. For additional optimisation of colloidal COD removal, the AH reactor needs an HRT of 8 h. The AF + AH system operated at an HRT of 4 + 8 h at 13 degrees C provided a high removal efficiency for all COD fractions. The achieved total COD removal was as high as 71% which is similar to values found in tropical areas. Moreover, 60% of the removed COD was converted to methane.     

SMSBR去除焦化废水中有机物及氮的特性

选用一体化膜—序批式生物反应器 (SubmergedMembraneSequencingBatchReac tor ,简称SMSBR)处理焦化废水 ,考察了能否通过膜分离的强化作用提高生物处理系统对焦化废水的处理效果 ,使出水COD达到新的排放标准 ( <10 0mg/L) ,并提高脱氮效率。研究结果表明 :在HRT为 32 .7h ,平均COD容积负荷为 0 .4 5kg/ (m3·d)的条件下 ,出水COD可以稳定在 10 0mg/L以下 (平均为 86.4mg/L) ;要使COD达到新的排放标准 ,进水COD容积负荷应低于 0 .67kg/ (m3·d) (该负荷下出水COD在 10 0mg/L上下波动 ,平均为 10 6.3mg/L) ;好氧段存在明显的反硝化现象 ,使COD的去除得到强化 ;在保证系统温度、碱度、溶解氧和不受进水COD负荷冲击的情况下 ,出水NH3-N可低于 1mg/L ,但泥龄太长所产生的微生物代谢产物抑制了硝化反应过程中的硝酸盐细菌 ,使好氧段出水NO2 -N/NOx-N平均为 91.1% ,因此系统获得极其稳定高效的短程硝化作用 ,有利于进一步脱氮 ;按“缺氧 1—好氧—缺氧 2”方式运行时 ,若“缺氧 2”的HRT>8.4 4h ,可实现 81.34 %的反硝化率 (外加碳源 :COD/N为 2 .1g/g) ,平均TN去除率为 87.2 % ,最高达 90 .2 %。     

Mesophilic and thermophilic anaerobic digestion with thermophilic pre-acidification of instant-coffee-production wastewater

The thermophilic and mesophilic digestion of instant-coffee-production wastewater in upflow anaerobic sludge blanket (UASB) reactors with thermophilic pre-acidification was studied over a period of more than 120 days. The UASB reactors had been seeded with granules adapted to this wastewater, and they previously operated in single-stage mode mesophilically or thermophilically. The thermophilic pre-acidification stage was operated with pH control or with 1.5 g l⁻¹ NaHCO₃ added to the feed, at retention times of 24, 18, 15 and 12 h. Up to 38% of the total influent chemical oxygen demand (COD) was converted to total volatile fatty acids at a 24-h hydraulic retention time (HRT), dropping to 21% at a 12-h HRT. It was found that control with NaOH to pH 6.0 at an HRT of 24 h was not required for efficient acidogenesis. The effluent from the acidogenic stage at pH 5.2 did not require prior neutralisation with NaOH before feeding to the methanogenic stage. The absence of neutralisation improved the performance of the thermophilic UASB reactor. Thermophilic digestion may be more sensitive to Na⁺ toxicity than mesophilic digestion. The thermophilic/mesophilic two-stage system gave a consistent improvement in performance (measured, for example, as % COD reduction) over the thermophilic/thermophilic two-stage system, especially at higher organic loading rates. Thermophilic pre-acidification gave an increase of 60% in the loading rate achievable with the mesophilic methanogenic stage (a 100% reduction in HRT) compared with the single-stage system.     

Halophilic biological treatment of tannery soak liquor in a sequencing batch reactor

Hypersaline wastewater (i.e. wastewater containing more than 35 gl(-1) total dissolved solids (TDS)) is generated by various industrial activities. This wastewater, rich in both organic matter and TDS, is difficult to treat using conventional biological wastewater treatment processes. Among the industries generating hypersaline effluents, tanneries are prominent in India. In this study, tannery wastewater from soak pit was treated in a lab-scale SBR for the removal of organic matter. The characterisation of the soak liquor showed that this effluent is biodegradable, though not easily, and highly variable, depending on the origin and the nature of the hides. TDS was in the range of 21-57 gl(-1) and COD was in the range of 1.5-3.6 gl(-1). This soak liquor was biologically treated in an aerobic sequencing batch reactor seeded with halophilic bacteria, and the performance of the system was evaluated under different operating conditions with changes in hydraulic retention time, organic loading rate and salt concentration. The changes in salinity appeared to affect the removal of organic matter more than the changes in hydraulic retention time or organic loading rate. Despite the variations in the characteristics of the soak liquor, the reactor achieved proper removal of organic matter, once the acclimation of the microorganisms was achieved. Optimum removal efficiencies of 95%, 93%, 96% and 92% on COD, PO4 3-, TKN and SS, respectively, could be reached with 5 days hydraulic retention time (HRT), an organic loading rate (OLR) of 0.6 kg COD m(-3)d(-1) and 34 g NaCl l(-1). The organisms responsible for nitrogen removal appeared to be the most sensitive to the modifications of these parameters.     

Removal of carbon and nutrients from domestic wastewater using a low investment, integrated treatment concept

An integrated chemical-physical-biological treatment concept for the low-cost treatment of domestic wastewater is proposed. Domestic wastewater was subjected to a chemically enhanced primary treatment (CEPT), followed by treatment in an upflow anaerobic sludge blanket (UASB) reactor. In addition, a regenerable zeolite was used to remove NH4+, either after CEPT pretreatment or after biological treatment in the UASB reactor. The CEPT pretreatment consisted of the addition of a coagulant (FeCl3) and an anionic organic flocculant and removed on average 73% of the total chemical oxygen demand (COD(t)), 85% of the total suspended solids, and 80% of PO4(3-) present in the wastewater. The UASB system, which consequently received a low COD(t) input of approximately 140 mg/L, was operated using a volumetric loading rate of 0.4 g COD(t)/L. d (hydraulic retention time [HRT]=10 h) and 0.7 g COD(t)/L. d (HRT=5 h). For these conditions, the system removed about 55% of the COD(t) in its influent, thus producing an effluent with a low COD(t) of approximately 50 mg/L. The zeolite, when applied in batch mode before the UASB reactor, removed approximately 45% of the NH4+, whereas its application as a post-treatment cartridge resulted in almost 100% NH4+ removal. The simple design and relatively low operating costs, due to low costs of added chemicals and low energy input (estimated at Euro 0.07-0.1 per m3 wastewater treated), combined with excellent treatment performance, means that this system can be used as a novel domestic wastewater treatment system for developing countries. Therefore, the system is called a Low Investment Sewage Treatment (LIST) system.     

An energy-efficient two-stage passively aerated trickling filter for high-strength wastewater treatment and reuse

This work aimed to assess the technical and energetic feasibility of a passively aerated laboratory-scale trickling filter, configured as a two-stage system, to produce urban wastewater (UWW) reusable in agriculture. The trickling filter was fed continuously with high-strength UWW at four hydraulic retention times (HRTs), that is, 10, 5, 2 and 1 day, corresponding to organic loading rates (OLRs) of 0.1, 0.2, 0.5 and 0.9 kg COD/m³/d, respectively. The results revealed a good performance in organic load removal and nitrification at the four HRTs. The trickling filter showed high organic pollutant removal efficiencies of up to 93%, 94% and 98% for chemical oxygen demand (COD), BOD₅ and total suspended solid (TSS), respectively, as well as high ammonia nitrogen removal above 96% at the shortest HRT of 1 day. All physicochemical parameters were significantly lower than the allowable limits set out in ISO 16075 for category C (non-food crop irrigation) irrigation water. The reuse of treated UWW in irrigation led to germination indexes and growth parameters of triticale (Triticosecale Wittm.) almost equal to those obtained using tap water. Energy use was found to be about 0.2754 kWh/m³ of treated wastewater, making it competitive with trickling filter plants reported in the literature. The simplicity and energy efficiency of the developed trickling filter system, combined with its capacity for almost full nitrification, make it appealing for sewage treatment in small communities in developing countries.     

Pre-acidification in anaerobic sludge bed process treating brewery wastewater

The effect of pre-acidification on anaerobic granule bed processes treating brewery wastewater was the focus of a comparison study employing two configurations, (a) a single stage upflow anaerobic sludge bed (UASB) and (b) an upflow acidification reactor in series with a methanogenic UASB. The pre-acidification reactor achieved 20±4% SCOD removal and 0.08±0.003 L of methane produced per gram of SCOD removal at a hydraulic retention time (HRT) of 0.75–4 h. Butyric acid was not detected and short chain fatty acids (SCFAs) were mainly acetic and propionic acids. The acidification ratio was about 0.42±0.02 g SCFAs as COD/g of influent COD.

Both systems’ critical loading rate to achieve 80% COD removal was established at 34–39 kg COD/m³ of total sludge bed volume per day. SCOD removal efficiency of 90±3% was achieved by both systems at an organic loading rate of 25±1 kg COD/m³ of total sludge bed volume per day, indicating that the installation of an acidification reactor had no effect in terms of the maximum granular activity, biomass granulation and the settleability of granules. At an organic loading rate of 67 kg COD/m³ of total sludge bed volume per day at an HRT of 1 h, the series system outperformed the single UASB by a removal of 62 compared to 57%.     

二级氧化工艺预处理对硝基苯甲酸废水的研究

以对硝基苯甲酸废水为处理对象,分别考察了O3／GAC、ClO2／GAC工艺以及二者的组合工艺对有机物的去除效率和改善废水可生化性的效果。结果表明,O3／GAC工艺的最佳O3投量为400mg／L,ClO2／GAC工艺的最佳ClO2投量为300mg／L;单级氧化工艺处理出水的有机物浓度仍较高,不能满足后续生化处理对进水水质的要求;O3／CAC-ClO2／GAC组合工艺的处理效果优于ClO2／GAC-O3／GAC组合工艺,其对COD的去除率可达75％左右,并使BOD5／COD值由原水的0．10升高到0．46,提高了废水的可生化性,减轻了后续生化处理的负荷,是对硝基苯甲酸废水的有效预处理方法。     

厌氧—3级好氧/缺氧生物膜工艺处理农村生活污水

对自流式厌氧—3级好氧/缺氧生物膜工艺处理低碳氮比农村生活污水的效能进行了应用研究。装置的处理量为18 m3/d,HRT为2.9 d,厌氧段的水力负荷为0.514 m3/(m3.d),生物球装填率为15%;3级好氧/缺氧生物膜段的水力负荷为1.029 m3/(m3.d),YDT弹性填料的装填率依次为50%、40%和25%,采用跌水充氧。连续8个月的监测结果表明:该工艺对COD、BOD5、NH3-N、TN和TP的去除率分别为73.7%、76.5%、90.7%、59.6%和69.7%;出水COD、BOD5、NH3-N、TN、TP、SS的平均浓度分别在34、15、2、7.7、0.9、5.2 mg/L以下,粪大肠菌群平均为5 200个/L,可用于农业灌溉和观赏性景观河道用水。该工艺的3级好氧/缺氧生物膜段能够同步进行硝化与反硝化除磷,适合于低碳氮比农村生活污水的处理。     

水力停留时间对BAF除污性能的影响

研究了水力停留时间(HRT)对曝气生物滤池(BAF)除污效果的影响。结果表明:HRT对BAF处理效果的影响较大,当HRT为0.63 h时,出水浊度、COD、氨氮和总氮浓度均较高,BAF的除污效果较差;当HRT为0.83 h时,出水COD浓度可降至50 mg/L以下,去除率可达到85.87%;当HRT为1.0 h时,BAF对浊度、氨氮和总氮均有较好的去除效果,去除率分别为95.98%7、7.08%4、0.09%,出水浊度<4 NTU、氨氮<8 mg/L、总氮<35 mg/L。     

悬浮填料生物系统处理炼油废水试验

为了提高A／O工艺的脱氮效果，采用悬浮填料生物系统来处理炼油废水。试验结果表明，当装填30％反应器容积的悬浮填料、进水NH3-N和COD分别为54～75mg／L和420～570mg／L、水力停留时间为24h时，对NH3-N和COD的去除率分别达96％和88％以上，出水水质达到了排放标准。此外，在悬浮填料曝气池中还发生了同步硝化反硝化现象。     

ABR-BAF工艺处理采油废水的中试研究

进行了利用折流板厌氧反应器（ABR）-曝气生物滤池（BAF）工艺处理江汉油田马-25污水处理站采油废水的中试研究，主要考察了ABR的除油效果、提高废水可生化性的作用以及BAF的运行参数、处理效果等。研究结果表明：当废水流量为0．3m^3／h时，ABR反应器对油的去除率平均为83．5％，对COD的去除率平均为40．8％，出水BOD，／COD值提高了24．8％。ABR一方面去除了采油废水中的大部分油，另一方面提高了采油废水的可生化性。当BAF的水力负荷为0．6m／h、进水COD平均为203．5mg／L时，出水COD平均为85．7mg／L，平均去除率为57．9％；对SS的去除率为82．7％。组合工艺对油、COD、BOD，和SS的总去除率分别为96．1％-96．9％、58．2％～75．1％、80．0％-93．1％和80．7％～87．1％。扫描电镜（SEM）观察结果显示：生物膜结构紧密，并且观察到裂口虫，生物相非常丰富。ABR-BAF工艺能够很好地处理采油废水，出水水质满足污水二级排放标准。     

Performance of an up-flow anaerobic stage reactor (UASR) in the treatment of pharmaceutical wastewater containing macrolide antibiotics

The performance of an up-flow anaerobic stage reactor (UASR) treating pharmaceutical wastewater containing macrolide antibiotics was investigated. Specifically, it was determined whether a UASR could be used as pre-treatment system at an existing pharmaceutical production plant to reduce the antibiotics in the trade effluent. Accordingly, a UASR was developed with an active reactor volume of 11 L being divided into four 2.75 L stages. Each stage of the reactor was an up-flow sludge blanket reactor and had a 3-phase separator baffle to retain biomass. The reactor was fed with real pharmaceutical wastewater containing Tylosin and Avilamycin antibiotics and operated with step-wise increases in the reactor organic loading rate (OLR) from 0.43 to 3.73 kg chemical oxygen demand (COD) m(-3)d(-1), and then reduced to 1.86, over 279 days. The process performance of the reactor was characterised in terms of its COD removal, Tylosin reduction, pH, VFA production, methane yield and sludge washout. At a total hydraulic retention time (HRT) of 4 d and OLR of 1.86 kg COD m(-3)d(-1), COD reduction was 70-75%, suggesting the biomass had acclimated to the antibiotics. Furthermore, an average of 95% Tylosin reduction was achieved in the UASR, indicating that this antibiotic could be degraded efficiently in the anaerobic reactor system. In addition, the influence of elevated Tylosin concentrations on the UASR process performance was studied using additions of Tylosin phosphate concentrate. Results showed similar efficiency for COD removal when Tylosin was present at concentrations ranging from 0 to 400 mgL(-1) (mean removal over this range was 93%), however, at Tylosin concentrations of 600 and 800 mgL(-1) there was a slight decline in treatment efficiency at 85% and 75% removal, respectively.     

Anaerobic sewage treatment in a one-stage UASB reactor and a combined UASB-Digester system

The treatment of sewage at 15 degrees C was investigated in a one-stage upflow anaerobic sludge blanket (UASB) reactor and a UASB-Digester system. The latter consists of a UASB reactor complemented with a digester for mutual sewage treatment and sludge stabilisation. The UASB reactor was operated at a hydraulic retention time of 6h and a controlled temperature of 15 degrees C, the average sewage temperature during wintertime of some Middle East countries. The digester was operated at 35 degrees C. The UASB-Digester system provided significantly (significance level 5%) higher COD removal efficiencies than the one-stage UASB reactor. The achieved removal efficiencies in the UASB-Digester system and the one-stage UASB reactor for total, suspended, colloidal and dissolved COD were 66%, 87%, 44% and 30%, and 44%, 73%, 3% and 5% for both systems, respectively. The stability values of the wasted sludge from the one-stage UASB reactor and the UASB-Digester system were, respectively, 0.47 and 0.36g CH(4)-COD/g COD. Therefore, the anaerobic sewage treatment at low temperature in a UASB-Digester system is promising.     

Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor

Feasibility of grey water treatment in an upflow anaerobic sludge blanket (UASB) reactor operated at different hydraulic retention time (HRT) of 16, 10 and 6h and controlled temperature of 30 degrees C was investigated. Moreover, the maximum anaerobic biodegradability without inoculum addition and maximum removal of chemical oxygen demand (COD) fractions in grey water were determined in batch experiments. High values of maximum anaerobic biodegradability (76%) and maximum COD removal in the UASB reactor (84%) were achieved. The results showed that the colloidal COD had the highest maximum anaerobic biodegradability (86%) and the suspended and dissolved COD had similar maximum anaerobic biodegradability of 70%. Furthermore, the results of the UASB reactor demonstrated that a total COD removal of 52-64% was obtained at HRT between 6 and 16 h. The UASB reactor removed 22-30% and 15-21% of total nitrogen and total phosphorous in the grey water, respectively, mainly due to the removal of particulate nutrients. The characteristics of the sludge in the UASB reactor confirmed that the reactor had a stable performance. The minimum sludge residence time and the maximum specific methanogenic activity of the sludge ranged between 27 and 93 days and 0.18 and 0.28 kg COD/(kg VS d).     

MIC反应器处理抗生素发酵废液的研究

采用逐步提高抗生素浓度和有机负荷(OLR)的方法,考察改进型内循环厌氧反应器(MIC反应器)对含万古霉素(VA)发酵废液的处理效果,并对微生物群落进行分析。结果表明,污泥经过驯化后,MIC反应器对VA发酵废液有较好的处理能力,当进水VA浓度为70 mg/L左右、水力停留时间(HRT)为4 d时,对MIC反应器运行没有抑制效应,此时COD去除率约为90%,VA去除率达到90%以上;当HRT为2 d、进水OLR为25 kgCOD/(m³·d)时,MIC反应器对VA发酵废液的COD去除负荷最大,为19. 5 kg/(m³·d)。通过微生物多样性检测结果发现,细菌群落在门水平上的优势菌为Bacteroidetes和Firmicutes。     

Purification capacity of a highly loaded laboratory scale tidal flow reed bed system with effluent recirculation

The purification capacity of a laboratory scale tidal flow reed bed system with final effluent recirculation at a ratio of 1:1 was investigated in this study. In particular, the four-stage reed bed system was heavily loaded with strong agricultural wastewater. Under the hydraulic and organic loading rates of 0.43 m3/m2.d and 1055 gCOD/m2.d, respectively, the average removal efficiencies obtained for COD, BOD5, SS, NH4-N and P were 77%, 78%, 66%, 62% and 38%, respectively. Even with the high loading rates, approximately 30% of NH4-N was converted into NO2-N and NO3-N from the mid-stage of the system where nitrification took place. The results suggest that the multi-stage reed bed system could be employed to treat strong wastewater under high loading, especially for the substantive mass removal of solids, organic matter and ammoniacal-nitrogen. Tidal flow combined with effluent recirculation is a favourable operation strategy to achieve this objective.     

HRT对填料生物膜A/O工艺处理效果的影响

利用投加填料的A/O工艺处理城市生活污水,在填料投加率为50%的条件下,考察了水力停留时间(HRT)对系统处理效果的影响.结果表明:在水力停留时间分别为9、7.5、6.5h的条件下,该工艺对COD和NH4 -N的去除率均能达到83%和97%以上,出水水质达到了<城镇污水处理厂污染物排放标准>(GB 18918-2002)的一级A标准.研究结果还表明,在HRT为9h的条件下,对有机物和氨氮的去除效果最好,可作为该工艺的运行参数.     

Macroscale and microscale analyses of nitrification and denitrification in biofilms attached on membrane aerated biofilm reactors

A membrane aerated biofilm reactor (MABR), in which O(2) was supplied from the bottom of the biofilm and NH(4)(+) and organic carbon were supplied from the biofilm surface, was operated at different organic carbon loading rates and intra-membrane air pressures to investigate the occurrence of simultaneous chemical oxygen demand (COD) removal, nitrification and denitrification. The spatial distribution of nitrification and denitrification zones in the biofilms was measured with microelectrodes for O(2), NH(4)(+), NO(2)(-), NO(3)(-) and pH. When the MABR was operated at approximately 1.0 g-COD/m(2)/day of COD loading rate, simultaneous COD removal, nitrification and denitrification could be achieved. The COD loading rates and the intra-membrane air pressures applied in this study had no effect on the start-up and the maximum rates of NH(4)(+) oxidation in the MABRs. Microelectrode measurements showed that O(2) was supplied from the bottom of the MABR biofilm and penetrated the whole biofilm. Because the biofilm thickness increased during the operations, an anoxic layer developed in the upper parts of the mature biofilms while an oxic layer was restricted to the deeper parts of the biofilms. The development of the anoxic zones in the biofilms coincided with increase in the denitrification rates. Nitrification occurred in the zones from membrane surface to a point of ca. 60microm. Denitrification mainly occurred just above the nitrification zones. The COD loading rates and the intra-membrane air pressures applied in this study had no effect on location of the nitrification and denitrification zones.     

预处理/厌氧生物处理敌百虫生产废水的研究

对敌百虫生产废水的处理工艺进行了研究,先采用破乳法和电解法进行预处理,然后再采用升流式厌氧污泥床(UASB)工艺进行厌氧处理,试验历时90 d,考察了系统的稳定性及pH值、温度和水力停留时间(HRT)等对反应器的影响。结果表明,当温度控制在30～35℃、pH值为6.8～7.5、进水COD为12 000 mg/L、HRT为72 h时,对COD的去除率可达到73%以上;厌氧处理后采用除磷药剂进行混凝沉淀,出水总磷浓度降为618 mg/L,对总磷的去除率为75.36%。