ASBR Applied to the Treatment of Biodiesel Production Effluent: Effect of Organic Load and Fill Time on Performance and Methane Production

The effect of organic matter and fill time on anaerobic sequencing batch reactor (5 L, 30°C, 8-h cycles, 50 rpm) efficiency has been analyzed. Organic matter was increased by the influent concentration. Fill times investigated were in the batch mode and fed-batch followed by batch. In the batch mode organic matter removal were 93%, 81%, and 66% for influent concentration of 500, 1,000, and 2,000 mgCOD/L (0.6, 1.29, and 2.44 gCOD/L.d), respectively. At 3,000 mgCOD/L (3.82 gCOD/L.d) operational stability could not be achieved. Removal efficiency was improved by increasing the fill time, and was 85% for the 1,000 mgCOD/L condition and fill times of 2 and 4 h, and 80 and 77% for the 2,000 mgCOD/L condition and fill times of 2 and 4 h, respectively. Hence, gradual feeding seemed to improve and to smooth the profiles of organic matter and volatile acids along the cycle with 78 to 96 NmLCH₄/gCOD.     

对硝基苯胺的工业化生产及生产废水的处理

重点介绍了对硝基苯胺的国内生产状况、详细叙述对硝基苯胺的合成机理、工业化生产的各个工序的操作工艺条件、生产注意事项及解决生产中出现的问题的方法。并对生产产生的废水处理工艺进行了深入的研究,以吹脱、高效催化氧化、混凝和生化结合的方法处理,采用该工艺处理的废水具有操作简单、成本低等优点,处理后的废水完全能满足排放的要求,本文对对硝基苯胺的生产具有较高的指导意义,能很好地指导对硝基苯胺低成本、低三废排放的生产。     

Effect of Feed Strategy on Methane Production and Performance of an AnSBBR Treating Effluent from Biodiesel Production

The aim of this work was to investigate the effect of different feeding times (2, 4 and 6 h) and applied volumetric organic loads (4.5, 6.0 and 7.5 gCOD L⁻¹ day⁻¹) on the performance of an anaerobic sequencing batch biofilm reactor (AnSBBR) treating effluent from biodiesel production. Polyurethane foam cubes were used as inert support in the reactor, and mixing was accomplished by recirculating the liquid phase. The effect of feeding time on reactor performance showed to be more pronounced at higher values of applied volumetric organic loads (AVOLs). Highest organic material removal efficiencies achieved at AVOL of 4.5 gCOD L⁻¹ day⁻¹ were 87 % at 4-h feeding against 84 % at 2-h and 6-h feeding. At AVOL of 6.0 gCOD L⁻¹ day⁻¹, highest organic material removal efficiencies achieved with 4-h and 6-h feeding were 84 %, against 71 % at 2-h feeding. At AVOL of 7.5 gCOD L⁻¹ day⁻¹, organic material removal efficiency achieved with 4-h feeding was 77 %. Hence, longer feeding times favored minimization of total volatile acids concentration during the cycle as well as in the effluent, guaranteeing process stability and safety.     

Methane Production Characteristics of an Anaerobic Co-Digestion of Pig Manure and Fermented Liquid Feed

Methane production characteristics of anaerobic co-digestion of pig manure (PM) and fermented liquid feed (FLF) were investigated in a continuous digester under mesophilic conditions. The experiment followed three phases. PM alone was digested in phase I. In phases II and III, PM and FLF were mixed in a ratio of 95:5 and 90:10 (% v/v), respectively. The specific methane yields (SMYs) during phases I, II, and III were 238, 278, and 326.8 mLCH₄·gVS⁻¹-added, respectively. It was due to the effect of balancing the feedstock carbon-to-nitrogen ratio by adding FLF. This improvement can also be attributed to the readily biodegradable compounds in the FLF. The higher SMY obtained in this study showed a positive synergistic effect in the anaerobic co-digestion of PM and FLF. The results also indicate that adding the FLF positively affected and maintained a constant pH level, avoiding volatile fatty acid accumulation and ammonia inhibition in the anaerobic digestion (AD). Thus, this study provides valuable information regarding the usage of unused or wasted FLF as a co-substrate for the practical AD of PM. The production of fermented liquid additives such as FLF to improve the methane production from the AD of PM is a potential novel alternative to food waste recycling in Japan, besides compost and animal feeding.     

Dry Anaerobic Co-digestion of Cow Dung with Pig Manure for Methane Production

The performance of dry anaerobic digestions of cow dung, pig manure, and their mixtures into different ratios were evaluated at 35?±?1 °C in single-stage batch reactors for 63 days. The specific methane yields were 0.33, 0.37, 0.40, 0.38, 0.36, and 0.35 LCH₄/gVS_r for cow dung to pig manure ratios of 1:0, 4:1, 3:2, 2:3, 1:4, and 0:1, respectively, while volatile solid (VS) and chemical oxygen demand (COD) removal efficiencies were 48.59, 50.79, 53.20, 47.73, 46.10, and 44.88 % and 55.44, 57.96, 60.32, 56.96, 53.32, and 50.86 %, respectively. The experimental results demonstrated that the co-digestions resulted in 5.10–18.01 % higher methane yields, 2.03–12.95 % greater VS removals, 2.98–12.52 % greater COD degradation and so had positive synergism. The various mixtures of pig manure with cow dung might persuade a better nutrient balance and dilution of high ammonia concentration in pig manure and therefore enhanced digester performance efficiency and higher biogas yields. The dry co-digestion of 60 % cow dung and 40 % pig manure achieved the highest methane yield and the greatest organic materials removal efficiency than other mixtures and controls.     

混凝沉淀法处理工业含氟废水的工艺研究

以半导体工业中的含氟废水为研究对象,采用混凝沉淀法对去除废水中氟离子进行了系统的工艺研究.以Ca(OH)2为沉淀剂,分别用聚合氯化铁(PFC)和聚合氯化铝(PAC)为混凝剂,并加入聚丙烯酰胺(PAM)助凝剂的方法,对药剂投加量、混凝剂种类、体系pH值、沉降时间等因素进行了实验探索.结果显示,PFC比PAC混凝效果好.当Ca(OH)2添加量为理论值的2.5倍,PFC用量为15mg/L,助凝剂PAM用量为4mg/L,体系的pH值在6～7时,其除氟效果最佳,此时废水中残留氟离子浓度可降低至5.5mg/L,远远低于国家规定的排放标准(10mg/L).     

Fermentative Hydrogen Production from Soybean Protein Processing Wastewater in an Anaerobic Baffled Reactor (ABR) Using Anaerobic Mixed Consortia

Fermentative H(2) production from soybean protein processing wastewater (SPPW) was investigated in a four-compartment anaerobic baffled reactor (ABR) using anaerobic mixed cultures under continuous flow condition in the present study. After being inoculated with aerobic activated sludge and operated at the inoculants of 5.98?gVSS?L(-1), COD of 5000?mg?L(-1), HRT of 16?h and temperature of (35?±?1) °C for 22?days, the ABR achieved stable ethanol-type fermentation. The specific hydrogen production rate of anaerobic activated sludge was 165?LH(2)?kg MLVSS(-1)?day(-1), the substrate conversion rate was 600.83?LH(2)?kg COD(-1)and the COD removal efficiency was 44.73% at the stable operation status. The ABR system exhibited a better stability and higher hydrogen yields than continuous stirring tank reactor under the same operational condition. The experimental data documented the feasibility of substrate degradation along with molecular H(2) generation utilizing SPPW as primary carbon source in the ABR system.     

Fed-batch Anaerobic Valorization of Slaughterhouse By-products with Mesophilic Microbial Consortia Without Methane Production

This work aimed at setting up a fully instrumented, laboratory-scale bioreactor enabling anaerobic valorization of solid substrates through hydrogen and/or volatile fatty acid (VFA) production using mixed microbial populations (consortia). The substrate used was made of meat-based wastes, especially from slaughterhouses, which are becoming available in large amounts as a consequence of the growing constraints for waste disposal from meat industry. A reconstituted microbial mesophilic consortium without Archaebacteria (methanogens), named PBr, was cultivated in a 5-L anaerobic bioreactor on slaughterhouse wastes. The experiments were carried out with sequential fed-batch operations, including liquid medium removal from the bioreactor and addition of fresh substrate. VFAs and nitrogen were the main metabolites observed, while hydrogen accumulation was very low and no methane production was evidenced. After 1,300 h of culture, yields obtained for VFAs reached 0.38 g/g dry matter. Strain composition of the microbial consortium was also characterized using molecular tools (temporal temperature gradient gel electrophoresis and gene sequencing).     

Biohydrogen Production from Cheese Whey Wastewater in a Two-Step Anaerobic Process

Cheese whey-based biohydrogen production was seen in batch experiments via dark fermentation by free and immobilized Enterobacter aerogenes MTCC 2822 followed by photofermentation of VFAs (mainly acetic and butyric acid) in the spent medium by Rhodopseudomonas BHU 01 strain. E. aerogenes free cells grown on cheese whey diluted to 10 g lactose/L, had maximum lactose consumption (～79%), high production of acetic acid (1,900 mg/L), butyric acid (537.2 mg/L) and H(2) yield (2.04 mol/mol lactose; rate,1.09 mmol/L/h). The immobilized cells improved lactose consumption (84%), production of acetic acid (2,100 mg/L), butyric acid (718 mg/L) and also H(2) yield (3.50 mol/mol lactose; rate, 1.91 mmol/L/h). E. aerogenes spent medium (10 g lactose/L) when subjected to photofermentation by free Rhodopseudomonas BHU 01 cells, the H(2) yield reached 1.63 mol/mol acetic acid (rate, 0.49 mmol/L/h). By contrast, immobilized Rhodopseudomonas cells improved H(2) yield to 2.69 mol/mol acetic acid (rate, 1.87 mmol/L/h). The cumulative H(2) yield for free and immobilized bacterial cells was 3.40 and 5.88 mol/mol lactose, respectively. Bacterial cells entrapped in alginate, had a sluggish start of H(2) production but outperformed the free cells subsequently. Also, the concomitant COD reduction for free cells (29.5%) could be raised to 36.08% by immobilized cells. The data suggest that two-step fermentative H(2) production from cheese whey involving immobilized bacterial cells, offers greater substrate to- hydrogen conversion efficiency, and the effective removal of organic load from the wastewater in the long-term.     

Anaerobic Digestion of Cassava Wastewater Pre-treated by Fungi

Cassava wastewater (cww) contains high concentrations of easily acidifying compounds, requiring a buffered system to allow a stable operation during anaerobic digestion (AD). The possibility to include a preliminary one-step fungi treatment aimed at raising the pH and buffering the cww prior to AD was studied. Preliminary tests were performed with a naturally grown fungal mixed culture, under aerated (AE), non-aerated (NAE) and initially oxygen-deprived (IOD) conditions. The cww was pre-treated by the NAE condition, until reaching a soluble chemical oxygen demand (COD) of 10 g?L^?1 and pH 6.4 (batch A) and pH 5.7 (batch B). The fungal mixed culture showed ability to biodegrade the cww with initial pH of 4.4 and 14,500 mg?COD?L^-1, raising the pH over 8.5, with only 13 % of COD remaining within 27 days for both AE and NAE condition. The fungal pre-treated-cww (FPTcww) was subjected to anaerobic digestion under different buffered (CaCO₃ and NaHCO₃) and non-buffered conditions. The FPTcww with initial pH at 6.4 provided stability during the anaerobic biodegradability tests, showing the possibility of system operation without buffer addition, with final pH around 7. The application of a fungal pre-treatment can be a promising strategy to permit the anaerobic digestion of carbohydrate-rich wastewaters.     

Effect of Fill Time on the Performance of Pilot-scale ASBR and AnSBBR Applied to Sanitary Wastewater Treatment

Many lab-scale studies have been carried out regarding the effect of feed strategy on the performance of anaerobic sequencing batch reactors (ASBR); however, more detailed pilot-scale studies should be performed to assess the real applicability of this type of operation. Therefore, the objective of this work was to assess the effect of feed strategy or fill time in a 1-m³ mechanically stirred pilot-scale sequencing batch reactor, treating 0.65 m³ sanitary wastewater in 8-h cycles at ambient temperature. Two reactor configurations were used: one containing granular biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam as inert support (denominated anaerobic sequencing batch biofilm reactor (AnSBBR)). The reactors were operated under five distinct feed strategies, namely: typical batch and fed-batch for 25%, 50%, 75%, and 100% of the cycle length. Stirring frequency in the ASBR was 40 rpm with two flat-blade turbine impellers and 80 rpm in the AnSBBR with two helix impellers. The results showed that both the ASBR and AnSBBR when operated under typical batch, fed-batch for 50% and 75% of the cycle length, presented improved organic matter removal efficiencies, without significant differences in performance, thus showing important operational flexibility. In addition, the reactors presented operation stability under all conditions.     

零价铁耦合厌氧微生物法在废水处理中的应用

零价铁(ZVI)与厌氧微生物的耦合是一项很有前景的技术,在难降解有机废水的去除中得到了广泛关注.该耦合技术将ZVI技术的高效性与厌氧生物技术的经济性有效融合,在多元微电场和厌氧微生物协同作用下,有效降低难降解有机物的生物抑制性和毒性.本文综述了此技术处理工业废水的潜在机理、实际应用中主要操作参数及影响条件以及处理含氯化...     

壳聚糖制备新工艺及生产废水处理

研究一种制备壳聚糖的新方法——“一步法”，即将虾、蟹壳酸浸、碱煮、脱乙酰后直接制得壳聚糖，分析了操作中各步骤的溶液组成、处理温度和处理时间等因索对壳聚糖脱乙酰度和粘均分子量的影响，并通过正交实验对工艺参数进行了优化。采用自然沉淀、两次中和及活性污泥法组合处理壳聚糖生产废水，不仅能使处理后的废水达标排放，而且可完全回用，实现零排放。废水处理过程中产生的废渣水洗后经压滤，可作饲科。     

酯交换法制备生物柴油的研究进展

作为一种对环境友好的可再生燃料生物柴油,对解决日益枯竭的石油资源和由石化柴油燃烧带来的环境问题具有重要意义.综述了运用酯交换反应制备生物柴油的几种方法的研究进展,对其优、缺点和研究趋势进行了归纳总结和展望.     

Immobilized Cells in Anaerobic Digestion for Methane from Poultry Manure

The two-stage immobilized microbe waste processor designed for sewage treatment by Messing has been modified to process poultry manure. The Messing reactor of 120-mL volume was modified and scaled up to a 4-L volume. Three different carrier materials have been investigated. Temperatures for each of the two stages were examined, and residence time as well as feed concentration were explored. Analytical data has been computer analyzed using multiple variable correlations and the results of this analysis have indicated directions for optimization.     

华根霉全细胞脂肪酶催化合成生物柴油

比较了5种不同商品化脂肪酶和自制的华根霉CCTCCM201021全细胞脂肪酶(RCL)催化油脂合成生物柴油的转化效果,结果表明,RCL能有效应用于无溶剂体系催化合成生物柴油.在无溶剂体系中对该酶催化生物柴油的转酯化反应工艺进行优化,考察了甲醇用量、体系含水量、酶的添加量和反应温度对生物柴油收率的影响,使生物柴油最终收率大于86.0%.在有机溶剂体系中选择不同有机溶剂作为助溶剂进行转酯化反应,发现logP值在4.0～4.5的有机溶剂具有较好的转化效果.其中以正庚烷为助溶剂的转酯化反应具有最高的生物柴油收率86.7%.在无溶剂体系中RCL催化转化油酸和模拟高酸价油脂合成脂肪酸甲酯的研究表明,该酶具有很好的催化合成生物柴油的潜力.