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Municipal Sewage (municipal + sewage)
Selected AbstractsExploring the diversity of bacterial communities in sediments of urban mangrove forestsFEMS MICROBIOLOGY ECOLOGY, Issue 1 2008Newton C. Marcial Gomes Abstract Municipal sewage, urban runoff and accidental oil spills are common sources of pollutants in urban mangrove forests and may have drastic effects on the microbial communities inhabiting the sediment. However, studies on microbial communities in the sediment of urban mangroves are largely lacking. In this study, we explored the diversity of bacterial communities in the sediment of three urban mangroves located in Guanabara Bay (Rio de Janeiro, Brazil). Analysis of sediment samples by means of denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments suggested that the overall bacterial diversity was not significantly affected by the different levels of hydrocarbon pollution at each sampling site. However, DGGE and sequence analyses provided evidences that each mangrove sediment displayed a specific structure bacterial community. Although primer sets for Pseudomonas, alphaproteobacterial and actinobacterial groups also amplified ribotypes belonging to taxa not intended to be enriched, sequence analyses of dominant DGGE bands revealed ribotypes related to Alteromonadales, Burkholderiales, Pseudomonadales, Rhodobacterales and Rhodocyclales. Members of these groups were often shown to be involved in aerobic or anaerobic degradation of hydrocarbon pollutants. Many of these sequences were only detected in the sampling sites with high levels of anthropogenic inputs of hydrocarbons. Many dominant DGGE ribotypes showed low levels of sequence identity to known sequences, indicating a large untapped bacterial diversity in mangrove ecosystems. [source] Performance of the hydrolyzation film bed and biological aerated filter (HFB,BAF) combined system for the treatment of low-concentration domestic sewage in south ChinaJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2006Xiao Ling Abstract The performance of the hydrolyzation film bed and biological aerated filter (HFB,BAF) combined system in pilot scale (with a daily treatment quantity of 600,1300 m3 d,1), operated for 234 days, for low-strength domestic sewage was assessed using different amounts of aeration, reflux ratios and hydraulic loading rates (HLR). In steady state it was found that the average removal efficiency of chemical oxygen demand (COD) and biological oxygen demand at 5 days (BOD5) were 82.0% and 82.2% and the average effluent concentrations were 15.8 mg L,1 and 9.4 mg L,1 respectively as the HFB was running at an HLR of 1.25,1.77 m3 m,2 h,1 and the BAF was running at an HLR of 1.56,2.21 m3 m,2 h,1. In general, the removal efficiency of total nitrogen (TN) fluctuated with the HLR, gas,water ratio and reflux ratio, so the ratio of gas to water should be controlled from 2:1 to 3:1 and the reflux ratio should be as high as possible. The effluent concentration of TN was 10.4 mg L,1 and the TN removal averaged 34.3% when the gas,water ratio was greater than 3:1 and the reflux ratio was 0.5. The effluent concentration and removal efficiency of NH4+ -N averaged respectively 2.3 mg L,1 and 78.5%. The overall reduction of total phosphorus (TP) was 30% and the average effluent concentration was 0.95 mg L,1. The removal efficiency of linear alkylbenzene sulfonates (LAS) reached 83.8% and the average effluent concentration was almost 0.9 mg L,1. The effluent concentration and removal efficiency of polychlorinated biphenyls (PCBs) were 0.0654 µ g L,1 and 37.05% respectively when the influent concentration was 0.1039 µ g L,1. The excess sludge containing water (volume 15 m3) was discharged once every 3 months. The power consumption of aeration was 0.06,0.09 kWh of sewage treated. The results show that the HFB,BAF combined technology is suitable for the treatment of low-concentration municipal sewage in south China. Copyright © 2005 Society of Chemical Industry [source] Improvement in biomass characteristics and degradation efficiency in modified UASB reactor treating municipal sewage: a comparative study with UASB reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Suprotim Das Abstract Low strength wastewaters (LSWs) are difficult to degrade efficiently in the upflow anaerobic sludge blanket (UASB) reactor. The possible reasons for poor treatment of LSWs in UASB are: (i) low mixing due to low biogas production (ii) frequent biomass washout at higher hydraulic loading rate due to low settleability of biomass. In the present study, lab scale UASB reactor and modified upflow anaerobic sludge blanket (MUASB) reactor were operated with municipal sewage containing chemical oxygen demand (COD) in range of 180,210 mg L,1 as LSW at three different hydraulic retention times (HRTs) of 8, 6, and 4 h. The changes in the biomass characteristics as well as degradation efficiency were compared with respect to time. During this operation, samples of biomass were taken from both reactors to measure total suspended solids (TSS), settling velocity, granular size and specific methanogenic activity (SMA). The overall COD removal in MUASB reactor was higher compared to UASB (84 and 67% respectively). After 150 days of operation, the settling velocity and SMA of MUASB biomass increased, but no significant change in settling velocity and SMA of UASB biomass was observed. The study shows that MUASB could be preferred over UASB for the treatment of municipal sewage as LSW. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||