Co-digestion of corn (nejayote) and brewery wastewater at different ratios and pH conditions for biohydrogen production

The capacity of a heat-treated sludge (HTS) to produce hydrogen from the mono- and co-digestion of corn (NW, pH 13.1) and brewery (BW, pH 3.8) wastewater was evaluated. The co-digestion of NW and BW was conducted with ratios (NW/BW) from 40/60 to 80/20 (vol/vol) at pH 6 and under different initial pH values (from 5.8 to 12.3) according to the substrates mixtures. With the initial pH adjusted to 6, the highest production (302 mL) occurred for the mono-digestion of NW, but hydrogen was produced in all incubations. For incubations under variable pH values, the highest hydrogen production was obtained with the ratio 60/40 (270 mL), followed by the ratio 65/35 (260 mL) with pH values of 10.8 and 10.4, respectively. The initial pH influenced the kinetic parameters, especially on maximum production and lag phase. For the ratio 60/40, with an alkaline pH value (10.4), the lag phase was delayed up to 122 h, but the highest volume of hydrogen was obtained with this condition. The Clostridium genus, present in all samples, could be associated as the main responsible for hydrogen production. Besides, the presence of Burkholderia genus, previously related to hydrogen production, was identified as the main involved in the culture at pH 10.8.     

Collateral Glucose-Utlizing Pathwaya in Diabetic Polyneuropathy

Diabetic polyneuropathy (DPN) is the most common neuropathy manifested in diabetes. Symptoms include allodynia, pain, paralysis, and ulcer formation. There is currently no established radical treatment, although new mechanisms of DPN are being vigorously explored. A pathophysiological feature of DPN is abnormal glucose metabolism induced by chronic hyperglycemia in the peripheral nerves. Particularly, activation of collateral glucose-utilizing pathways such as the polyol pathway, protein kinase C, advanced glycation end-product formation, hexosamine biosynthetic pathway, pentose phosphate pathway, and anaerobic glycolytic pathway are reported to contribute to the onset and progression of DPN. Inhibitors of aldose reductase, a rate-limiting enzyme involved in the polyol pathway, are the only compounds clinically permitted for DPN treatment in Japan, although their efficacies are limited. This may indicate that multiple pathways can contribute to the pathophysiology of DPN. Comprehensive metabolic analysis may help to elucidate global changes in the collateral glucose-utilizing pathways during the development of DPN, and highlight therapeutic targets in these pathways.     

Short‐time estimation of biogas and methane potentials from municipal solid wastes

Biogas (GB) and methane (BMP) potentials are important parameters for the energy potential of the anaerobic digestion of municipal solid wastes (MSW) and to design full‐scale facilities. However, no standard protocol has been defined for this measure. Several samples of mixed MSW and the source‐selected organic fraction of municipal solid waste (OFMSW) obtained at different stages of their mechanical‐biological treatment were analyzed. GB and BMP values obtained at different times were correlated. Biogas potentials calculated at 3, 4, 5, 6, 7, 14, 21, 50 and 100 days correlated well for the OFMSW samples. In the case of the MSW samples, only GB values obtained at times of 14 or more days correlated well with the ultimate biogas production (considered at 100 days). The biogas potential analyzed at 21 days (as proposed in some standard methods) accounted for 77% of the total biogas potential in OFMSW samples and for 71% in the MSW samples. These results are useful for the correct design and operation of anaerobic digestion plants in terms of retention time estimation and expected biogas and methane production. Copyright © 2011 Society of Chemical Industry     

Treatment of high‐fat‐containing dairy wastewater in a sequential UASBR system: influence of recycle

BACKGROUND: Raw cheese whey originating from white cheese production results in a strong and complex wastewater excessively rich in organic matter (chemical oxygen demand, COD = 28–65 g L^?1), fatty matter (14–24.5 g L^?1) and acidity (3.9–6.1 g L^?1). It was treated in a three‐stage configuration consisting of a pre‐acidification (PA) tank and sequential upflow anaerobic sludge bed reactors (UASBRs) at 2.8–7 g COD L^?1 day^?1 organic loading rates, during which the effects of effluent recycling at low rates and promoted SRB activity were investigated. Acidification, volatile fatty acids (VFA), COD and fatty matter removal and volatile solids were monitored throughout the system during the study. RESULTS: Recycling of the effluent promoted VFA and COD removal as well as pH stability in both stages of the UASBRs and the effluent where high alkalinity levels were recovered reducing alkali requirement to 0.05 g OH g^?1 COD_applied. Higher removal rates of 71–100 and 50–92% for VFA and COD were obtained by use of recycling. Fatty matter was removed at 63–89% throughout the study. Volatile solids build‐up was significant in the inlet zones of the UASBRs. CONCLUSIONS: The system produced efficient acidification in the PA tank, balanced pH levels and an effluent high in alkalinity and BOD/COD ratio. Efficient VFA removal and solids immobilization was obtained in both stages up to the highest loading rate. Recycling improved the system performance under high fatty matter loading conditions. A major advantage of the sequential system was that the second stage UASBR compensated for reduced performance in the first stage. Copyright © 2010 Society of Chemical Industry     

水性切削液环境专用厌氧胶的研制

通过改善厌氧胶主体树脂的合成条件,在配方中添加耐水/耐热树脂及单体,有机硅烷偶联剂作为增强剂,制备了一种使用水性切削液进行石英晶体加工过程中专用厌氧胶粘剂。检测结果表明,该厌氧胶能完全满足水性切削液环境下石英晶体的加工要求。     

氮浓度对新型生物电化学-颗粒污泥反应器运行的影响

探讨了新型生物电化学-颗粒污泥反应器在不同进水氮浓度下的脱氮效能与产电性能，并从颗粒污泥的关键酶活性、胞外聚合物组分以及微生物群落分布等角度系统研究了其影响机制。结果表明，COD、NO₃^--N、NO₂^--N和溶解性甲烷在第Ⅰ、Ⅱ、Ⅲ、Ⅳ阶段（进水NO₃^--N和NO₂^--N浓度分别为60 mg·L^-1和20 mg·L^-1、100 mg·L^-1和40 mg·L^-1、140 mg·L^-1和60 mg·L^-1、180 mg·L^-1和80 mg·L^-1）均得以有效去除，其中COD去除率在第Ⅳ阶段效果最佳，去除率达96%以上，NO₃^--N出水浓度在第Ⅱ阶段更为稳定，其去除率达99%以上，NO₂^--N去除率在各阶段均达99%以上；该反应器最大的功率密度与输出电压值为第Ⅳ阶段的4号格室，分别为471.2 mV·m^-3和608.1 mV。污泥疏松型胞外聚合物（LB-EPS）中多糖与蛋白含量最高为第Ⅱ阶段的5号格室，分别为13.7 mg·g^-1和14.7 mg·g^-1；1号格室污泥中辅酶F₄₂₀活性最低，进水氮浓度的增大提高了污泥中蛋白酶活性。由第Ⅰ阶段至第Ⅳ阶段，该反应器中变形菌门（Protebaoteria）相对丰度减少，而绿弯菌门（Chloroflexi）、厚壁菌门（Firmicutes）和浮霉菌门（Planctomycetes）相对丰度增加；具有脱氮作用的陶厄氏菌属（Thauera）在1号格室减少了8.64%，但该反应器脱氮效果未受到影响；甲烷丝状菌属（Methanothrix）在4号格室相对丰度增至12.3%，表明产甲烷菌可在该反应器中与其他菌群联营共存。     

An Integrated Approach to Lysis-Cryptic Growth (Sludge Ozonation) and Sequencing Batch Reactor Coupled to an Anaerobic Side-Stream Reactor (SBR-ASSR): Performance and Characteristics

ABSTRACT

Anaerobic side-stream reactors (ASSR) have been suggested to reduce waste activated sludge volumes benefiting from relatively low capital/operation costs and design simplicity. In this study, an evaluation of the feasibility of combining the ASSR system with the lysis-cryptic growth (ozonation) process was made so that a part of the sludge which passed through the ASSR anaerobic tank would be then treated by ozonation before returned to the aeration tank. The main independent factor was the ozonation flowrate (OFR), which is defined as the percent of return sludge which passed through the both the anaerobic tank and the ozonation unit. Three systems were studied, an ASSR control without ozonation (OFR-0), a combined ASSR with ozonation designated as OFR-2.5 (anaerobic interchange rate [AIR] of 10% per day and 25% of the exchanged sludge being ozonated [ozone interchange rate or OIR]), and OFR-3.1 (AIR = 12.5%, OIR = 25%). The results revealed that the insertion of an ozonation step led to an enhanced total microbial activity, eukaryotic population, and nitrogen removal. The linear relationship between the observed yield and the specific oxygen uptake rate indicated that microbial predation was the major relevant mechanism for the enhanced sludge reduction. The results of measurements of particle size distribution, and sludge dewaterability rates suggest that additional studies are needed to better understand and optimize this system.