A novel MBBR–MFC integrated system for high-strength pulp/paper wastewater treatment and bioelectricity generation

ABSTRACT

In this study, a system combining an anaerobic moving-bed biofilm reactor and a microbial fuel cell (MFC) was designed for simultaneous bioelectricity generation and pulp/paper wastewater (PPW) treatment. After 22 days, when hydraulic retention time (HRT) was set at 72 h, ceramsite-added MFC (C-MFC) showed better bioelectricity performance with power density of 94.5 mW/m² and internal resistance of 35.7 Ω, as compared to the control without ceramsite (W-MFC) (56.1 mW/m², 54.3 Ω). Chemical oxygen demand (COD) removal efficiencies of C-MFC and W-MFC were 65.6% and 51.3%, respectively. The C-MFC demonstrated its superior electrochemical performance compared to the W-MFC.     

Characteristics of simultaneous nitrogen and phosphorus removal in a pilot-scale sequencing anoxic/anaerobic membrane bioreactor at various conditions

This study was conducted to evaluate the performance of pilot-scale sequencing anoxic/anaerobic membrane bioreactor (SAM) process under various real situations. During the pilot experiment, the effect of three important operational parameters, such as hydraulic retention time (HRT), solids retention time (SRT) and internal recycling time mode were estimated and the long-term membrane fouling behaviour was also investigated. During the operation period, the COD removal efficiency was higher than 95% regardless of change of operational conditions because the membrane significantly contributed to remove COD by the complete retention of all particulate COD and macromolecular COD components. The change of Ax/An ratio representing internal recycling time mode significantly affected on nitrogen and phosphorus removal. As increasing Ax/An ratio, nitrogen removal efficiency increased but phosphorus removal efficiency decreased. As HRT decreased, phosphorus removal efficiency increased and nitrogen removal efficiency also increased until a certain limit of HRT (6.5 h in this study). However, when HRT decreased over the limit, nitrogen removal efficiency decreased because of insufficient nitrification. Relation between phosphorus removal efficiency and SRT was a little bit complex because SRT determined both the phosphorus content in the sludge and the sludge wasting rate. However, in this study, the shorter SRT resulted in the higher phosphorus removal efficiency. The effect of changes in all operational conditions was sensitive on phosphorus rather than on nitrogen removal efficiency. The increasing in influent flowrate resulted in the increase of flux and caused a rapid membrane fouling. Thus, the flux of 7.7 L/m²/h was more desirable compared to the 10.7 or 15.4 L/m²/h in this study.     

Integration of continuous biological and chemical (ozone) treatment of domestic wastewater: 1. Biodegradation and post‐ozonation

The continuous treatment of domestic wastewater by an activated sludge process and by an integrated biological–chemical (ozone) oxidation process were studied in this work. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), absorbance at 254 nm (UV₂₅₄) and nitrogenous compound content were the parameters followed in order to evaluate the performance of the two processes. Experimental data showed that both UV₂₅₄ and COD reductions are improved in the combined biological–chemical oxidation procedure. Thus, reductions of 59.1% and 37.2% corresponding to COD and UV₂₅₄, respectively were observed after the biological process (hydraulic retention time = 5 h; mixed liquor volatile suspended solids concentration = 3142 g m⁻³) compared with 71.0% and 78.4% obtained when a post‐ozonation step ( D _O3 = 41.7 g m⁻³) was included. During conventional activated sludge treatment, appropriate nitrification levels are only achieved with high hydraulic retention time and/or biomass concentration. Ozonation after the secondary treatment, however, allows improved nitrogen content reduction with total nitrite elimination. Post‐ozonation also leads to a higher biodegradability of the treated wastewater. Thus, the ultimate BOD/COD ratio goes from 0.16 after biological oxidation to 0.34 after post‐ozonation with 41.7 g O₃ m⁻³. © 1999 Society of Chemical Industry     

外循环人工快渗池深度处理焦化废水研究

采用外循环人工快渗系统(ECCRI)深度处理焦化废水。结果表明,水力负荷对COD和NH3-N去除率的影响较大,增大湿干时间比会提高NH3-N去除率,但对TN影响较小,出水循环能显著提高TN的去除率。在优化条件下,当水力负荷率为0.9 m3/(m2.d),湿干时间比为1/2及循环体积比为0.2时,ECCRI对COD和NH3-N、TN的平均去除率为77%,60.9%及54.9%,出水平均COD和NH3-N、TN分别为65 mg/L和12.8、24.4 mg/L。     

序批式活性污泥法处理德士古气化废水

采用SBR(序批式活性污泥法)工艺对德士古气化工艺废水处理,结果表明:在碳、氮、磷比例理想的情况下,达到了既去除有机物又能脱氮的效果。当总停留时间控制在5～9 h、污泥负荷为0.41～0.96 kg BOD5/(kgMLSS.d)时,出水BOD5浓度为0～30 mg/L,去除率达88%～89%;出水COD浓度为10.7～32.2 mg/L,去除率达87%～89%;出水NH3-N浓度为2.83～9.23 mg/L,去除率达95%～97%。     

Rapid startup of a hybrid UASB-AFF reactor using bi-circulation

The startup of a hybrid system consisting of an upflow anaerobic sludge blanket (UASB) and an anaerobic fixing filter (AFF) with internal hydraulic circulation and external sludge circulation was investigated. The reactor was rapidly cultivated using municipal sludge as a seed 38 d after a failed startup. During the operation, the average size of the granular sludge increased from 111 μm to 264 μm, and the sludge was uniformly distributed in the reacting region. Efficient performance was attributed to good hydraulic contact between the substrate and sludge and the low loss of sludge. However, excessive hydraulic circulation resulted in a sharp decline in the effectiveness. After a pause in the operation, a second startup was rapidly completed in 15 d, during which time the organic load reached 15.4 COD/(m³ d).     

外循环对IC反应器运行效果的影响

为改善已形成颗粒污泥的IC反应器运行性能,增设外循环装置,并在回流比分别为0、1.0、2.0、3.0、4.0的情况下,进行了系统运行稳定性研究。与无外循环的情况相比,在设定的回流比范围内,附加外循环不会破坏反应器内部厌氧条件,反应器运行稳定;在进水COD为6000 mg·L^-1左右,系统HRT约为10 h,容积负荷为14 kg·m^-3·d^-1的情况下,系统污泥MLSS有所增加,COD去除率随回流比的增大而增加,最高可达97.3%,出水COD低至160 mg·L^-1;随回流比的增大,产气总量逐渐增加且最终可达171.2 L·d^-1,甲烷产量先增加后趋于稳定,在回流比为2.0时可达到91.7 L·d^-1;增加外循环运行一段时间后,厌氧颗粒污泥生物相更为丰富,产甲烷优势菌由甲烷杆菌转变为甲烷八叠球菌。结合能耗和去除效率等考虑,回流比为2.0时最佳。     

Effect of COD/NO3-N ratio on the performance of a hybrid UASB reactor treating phenolic wastewater

The effect of COD/O₃⁻-N ratio on the biodegradation of complex phenolic mixture was studied in bench scale hybrid upflow anaerobic sludge blanket (HUASB) reactors. HUASB reactor is a combination of a UASB unit at the lower part and an anaerobic fixed film at the upper end. The aim of this study was to evaluate the biodegradability of phenolic mixture (from synthetic coal wastewater) as the only carbon and energy source in continuous experiments using nitrate as the final electron acceptor. Synthetic coal wastewater contained phenol (490 mg/L); m-,o-,p-cresols (123.0 mg/L, 58.6 mg/L, 42 mg/L); 2,4-, 2,5-, 3,4- and 3,5 dimethyl phenols (6.3 mg/L, 6.3 mg/L, 4.4 mg/L and 21.3 mg/L) as major phenolic compounds representing the complex phenolic mixture. Nitrate nitrogen loading was increased from 0.11 g/m³/d to 0.5 g/m³/d in order to keep COD/NO₃⁻-N ratio as 20.1, 14.85, 9.9, 6.36 and 4.45. An input phenolics concentration of 752 mg/L and hydraulic retention time (HRT) of 24 h was maintained through out the study. Removal of phenolic mixture was found to increase with the lowering of COD/NO₃⁻-N ratio. Maximum phenolics removal of 98% was achieved at a COD/NO₃⁻-N ratio of 6.36. However, phenolics removal got adversely affected when COD/NO₃⁻-N ratio was reduced below 6.36. A nitrogen production efficiency of 78% was obtained according to nitrate consumption. Simultaneous denitrification and methanogenesis was observed in all the reactors throughout the study, demonstrating that denitrification is a feasible alternative for the treatment of coal wastewater. Granules degrading complex phenolic mixture were of diameter 1.6–2.25 mm.     

缺氧/好氧移动床生物膜反应器短程脱氮工艺深度处理煤化工废水性能

煤化工废水生化处理出水仍含有大量有毒和难降解污染物,对环境具有严重的危害,采用缺/好氧移动床生物膜反应器（ANMBBR-MBBR）复合生物短程脱氮技术对煤化工废水进行深度处理。试验结果表明,生物组合工艺有效缓解了废水有毒抑制物和低碳氮比对生物脱氮工艺的负面作用,最佳运行条件为水力停留时间12 h,硝态氮/亚硝态氮混合液回流比200%,该工艺对COD、氨氮和总氮的去除率分别为68.1%、84.0%和74.7%,相应的出水浓度分别为48.0、4.8和13.9 mg·L^-1,均达到了国家城镇污水处理厂污染物排放一级A标准;高有毒负荷下,与传统的A²O生物脱氮工艺相比,该组合工艺具有更加稳定和高效的脱氮效能;而且ANMBBR有效地提高了废水生物降解性（BOD₅/COD值增加至0.3）,有利于短程硝化的高效运行,MBBR处理后出水有毒抑制物的数量和种类分别减少了84.4%和54.5%。因此,该组合工艺具有性能高效稳定和经济节约的技术优势,适于煤化工废水深度处理的工程化应用。     

Evaluation of an Integrated System for Pig Slurry Treatment

A system for pig slurry treatment, where anaerobic digestion, nitrification and denitrification have been integrated in a unique process treatment, has been investigated. This configuration allowed both removal of Chemical Oxygen Demand (COD) and a decrease in nitrogen content. Strategies are reported to bring enough COD to the denitrification system. Results (90% reduction in COD, 99·8% reduction in NH₄⁺-N and 98·8% reduction in NO₃⁻N) show this process could be considered a good alternative to treat these wastes. © 1997 SCI.     

UBF-BAF处理羧甲基纤维素冷凝液特性

采用UBF-BAF组合工艺对多效蒸发食品添加剂羧甲基纤维素(CMC)产生的酸性冷凝液进行生物降解,考察了UBF-BAF组合工艺参数,构建了基于化学需氧量(COD)去除的UBF反应动力学模型,并对UBF和BAF反应器生物膜中的生物学特征进行了解析,初步揭示出UBF-BAF处理CMC冷凝液的特性. 其适宜的运行参数为：UBF的水力停留时间24 h,BAF的水力停留时间5 h,温度20~40℃,pH=6.5~7.5,BAF反冲洗周期5~7 d. 当进水COD浓度为2388~4000 mg/L时,UBF反应器对COD的去除率高于84.26%,BAF反应器对COD的去除率高于80.53%,最终出水达到《污水综合排放标准(GB 8978-2002)》一级排放要求.     

Nitrogen compounds removal in a packed bed external loop airlift bioreactor

A packed bed external loop airlift bioreactor (PBELAB) was proposed as an alternative treatment system for wastewater containing ammonia and nitrate compounds. The 60L PBELAB consisted of aeration and non-aeration zones, both of which were packed with plastic bioballs to enhance the surface area for the attachment of bacteria. The system was able to achieve complete removal of all nitrogen compounds with simultaneous nitrification and denitrification, i.e., ammonia was decomposed in the aeration zone and nitrate was biodegraded in the non-aeration zone. At normal operation, the nitrification rate obtained from the system was in the range of 0.14-0.87 gNH₃-N/m²d and the denitrification rate was 0.04 gNO₃-N/m²d. The factors found to have great influence on the system included dissolved oxygen concentration and biofilm thickness. In addition, PBELAB was proven to perform well under nitrate shock load condition.     

Fe/C微电解-Fenton氧化-混凝沉淀-生化法处理松节油加工废水

采用Fe/C微电解-Fenton氧化-混凝沉淀-生化法组合工艺处理松节油加工废水,首选通过正交和单因素实验,确定Fe/C微电解、Fenton氧化、混凝沉淀等工艺运行的最佳条件,考察COD的去除效果及BOD5/CODCr比值的改变,探讨废水的可生化性的改善;然后通过BAF工艺进行生化处理,确定工艺影响参数,考察废水达标排放的可行性. 结果表明,在铁屑投加量为100 g/L,Fe/C质量比为1.5:1,H2O2投加量为40 mL/L,PAM投加量为8 mg/L时,废水经Fe/C微电解、Fenton氧化、混凝沉淀等工艺预处理后出水COD为200~450 mg/L,COD去除率达98%,BOD5/CODCr比值由0.13提高到0.64,满足后续生化处理要求;生化处理单元采用曝气生物滤池,在水力停留时间为5 h、DO浓度为2~3 mg/L,处理后出水COD、动植物油和色度为50~90, 3~10和30~50 mg/L时,出水水质达到《污水综合排放标准》(GB8978-1996)一级标准.     

Bioremediation of contaminated air using an external-loop airlift bioreactor

Biological air treatment methods are gaining popularity in the chemical industries due to their low cost and ability to convert many hazardous volatile organic compounds (VOCs) into harmless byproducts. An external loop, airlift bioreactor (ELAB) is used to separately bioremediate two prototype, water-soluble VOC compounds: p-cresol and ethanol. In both cases, the effluent air was cleansed and bioremediated to below detectable limits (beyond 99.7% removal) due to the efficient scrubbing action of the ELAB. The bioreactor continued to provide this removal efficiency up to maximum air p-cresol concentration of 0.6 g/m³ and ethanol concentration of 110 g/m³ and at bioreactor loading rates up to 8 g/m³ h for p-cresol and 220 g/m³ h for ethanol. A dynamic and quasi-steady state, biokinetic model is shown to predict the transient bioremediation process very well using batch growth biokinetic parameters.     

粉煤灰复合滤料曝气生物滤池处理污水试验研究

采用粉煤灰复合滤料曝气生物滤池(BAF)装置处理污水,研究了气水体积比、水力负荷、进水污染物负荷对COD和NH3-N去除效果的影响。结果表明,在进水COD和NH3-N的质量浓度分别为200mg/L和25mg/L时,适宜的气水体积比为10:1,COD和NH3-N的去除率能够分别达到77.93%和84.78%;适宜的水力负荷为1.01 m3/(m.2h),COD和NH3-N的去除率能够分别达到87.88%和90.01%。反应器具有较强的抗污染物冲击负荷的能力,有机负荷在1.03～3.68kg/(m.3d)时,COD去除率均保持在75%以上;当氨氮负荷在0.22～0.44kg/(m.3d)化时,NH3-N去除率均保持在85%以上。     

多段式序批式活性污泥法(SBR)工艺对污染物的去除效果

分段式SBR是将传统SBR的曝气和沉淀过程在时间上进行分段,在不同段数厌氧/好氧/缺氧状态下交替运行。该试验以模拟生活污水为处理对象,在有效容积为12 L的SBR反应器中进行了分段进水试验研究,结果表明:在15~30℃的温度范围内,当系统的水力停留时间为8 h,污泥龄为15 d时,COD,NH3-N,TN和TP的去除率分别可达88.9%,99.61%,78.9%和94.21%,出水水质良好,无需另加碳源。     

Performance of inverse fluidized bed bioreactor in treating starch wastewater

Aerobic digestion of starch industry waste-water was carried out in an inverse fluidized bed bioreactor using low-density (870 kg/m³) polypropylene particles. Experiments were carried out at different initial substrate concentrations of 2250, 4475, 6730, and 8910 mg COD/L and for various hydraulic retention times (HRT) of 40, 32, 24, 16, and 8 h. Degradation of organic matter was studied at different organic loading rates (OLR) by varying the HRT and the initial substrate concentration. From the results it was observed that the maximum COD removal of 95.6% occurred at an OLR of 1.35 kg COD/(m³·d) and the minimum of 51.8% at an OLR of 26.73 kg COD/(m³·d). The properties of biomass accumulation on the surface of particles were also studied. It was observed that constant biomass loading was achieved over the entire period of operation.     

Effect of a chemical synthesis‐based pharmaceutical wastewater on performance,acetoclastic methanogenic activity and microbial population in an upflow anaerobic filter

The performance of an upflow anaerobic filter (UAF) treating a chemical synthesis‐based pharmaceutical wastewater was evaluated under various operating conditions. During start‐up, the UAF was initially fed by glucose till an organic loading rate (OLR) of approximately 7.5 kg COD m^?3 day^?1 with a hydraulic retention time of 2.3 days. A soluble COD removal efficiency of 98% was achieved before the addition of the wastewater. Initially, the filter inertia was acclimatized to the wastewater by sequential feeding of 10% (w/v), 30% (w/v) and 70% (w/v) of the pre‐aerated wastewater mixed with glucose followed by a 100% (w/v) pre‐aerated wastewater. During the operation, the COD removal efficiency and methane yield decreased to 75% and 0.30 m³ CH₄ kg^?1 COD_removed respectively. As the UAF became accustomed to the pre‐aerated wastewater, raw wastewater was fed in increasing ratios of 20% (w/v), 60% (w/v) and 80% (w/v) with the pre‐aerated wastewater as the remaining part. During this stage of the operation, a COD removal efficiency in a range of 77–86% was achieved and the methane yield decreased to 0.24 m³ CH₄ kg^?1 COD_removed. Finally, 100% (w/v) raw wastewater was fed and a COD removal efficiency of 65% was achieved with a methane yield of 0.20 m³ CH₄ kg^?1 COD_removed. At the end of the operation, acetoclastic methanogenic activity was only measured in the bottom section of the UAF, this showed a 90% reduction in comparison with activity of inoculation sludge. Microscopic examinations revealed that rod‐shaped methanogens remained as the dominant species whereas Methanosarcina‐like species and filaments were present only in insignificant numbers along the UAF. © 2002 Society of Chemical Industry     

Simultaneous organic carbon and nitrogen removal in an SBR controlled at low dissolved oxygen concentration

Simultaneous organic carbon and nitrogen removal was studied in a sequencing batch reactor (SBR) fed with synthetic municipal wastewater and controlled at a low dissolved oxygen (DO) level (0.8 mg dm^?3). Experimental results over a long time (120 days) showed that the reactor achieved high treatment capacities (organic and nitrogen loading rates reached as high as 2.4 kg COD m^?3 d^?1 and 0.24 kg NH₃‐N m³ d^?1) and efficiencies (COD, NH₃‐N and total nitrogen removal efficiencies were 95%, 99% and 75%). No filamentous bacteria were found in the sludge even though the reactor had been seeded with filamentous bulking sludge. Instead, granular sludge, which possessed high activity and good settleability, was formed. Furthermore, the sludge production rate under low DO was less than that under high DO. Significant benefits, such as low investment and less operating cost, will be obtained from the new process. © 2001 Society of Chemical Industry     

生活污水的一体化反应器同步脱氮除磷研究

根据污水生物脱氮除磷原理设计了一套一体化反应器,并在其中分别投加普通生物悬浮载体和双室悬浮载体,以研究两者对生活污水同步脱氮除磷的效果。结果表明,在相同HRT下、温度控制在20～30℃和pH为6.5～7.8时,双室悬浮载体对污水总氮的平均去除率比普通生物悬浮载体的高近10%;但是两者对总磷及COD的去除效果相近,且对COD的去除效果较好,平均去除率在90%以上;Grau模型计算表明,HRT为12 h时,反应器中投加双室悬浮载体后的污水底物降解常数最大(2.18)。因此,把双室悬浮载体及其一体化反应器用于污水的同步脱氮除磷是一种高效的生活污水处理方法。