A bioflocculant M-1 produced by Enterobacter sp. EP3 was investigated with regard to its flocculanting characteristics and mechanism. 2.0 mg/l M-1 showed the maximum flocculating activity of 96% in 5.0g/l Kaolin suspension containing 8mM CaCl2 and that its flocculating activity was more than 80% in a wide pH range (4.0-12.0). Chemical analyses indicated that the biopolymer M-1 was mainly a polysaccharide, mainly consist of rhamnose and glucose with a molar ratio of 9:1. Infrared spectrophotometry showed the presence of carboxyl, hydroxyl and methoxyl groups in M-1 molecular. Flocculation of Kaolin suspension with M-1 acted as a model to explore the flocculating mechanism in which bridging mediated by Ca2+ was proposed as the primary action based on the experimental observations.

Denitrification and dissimilatory nitrate reduction to ammonium (DNRA), are two competing pathways in nitrate reducing process. In this study, a series of C/S ratios from 8:1 to 2:4 was investigated in a sequencing biofilm batch reactor (SBBR) to determine the role of reducers (sulfide and acetate) on their competition. The results showed the proportion of DNRA increased in high electron system, either in organic rich or in sulfide rich system. The highest DNRA ratio increased to 16.7% at the C/S ratio of 2:3. Excess electron donors, particularly sulfide, were favorable for DNRA in a limited nitrate environment. Moreover, a higher reductive environment (ORP <-400 mV) can be used as an indicator for the occurrence of DNRA. 16s RNA analysis demonstrated that Grobacter was the main functional bacteria of DNRA in the organic rich system, while Alphaproteobacteria and Desulfomicrobium were dominant DNRA bacteria in the sulfide rich system. DNRA cultivation could enrich nitrogen conversion pathways in conventional denitrification systems. This provides the great insight into nitrogen removal in high nitrogen containing sewage with low C/N.

An innovative biological wastewater treatment system for the removal of organic carbon, sulfur and nitrogen was developed based on biological phase-separation principle. This system consists of three reactors integrated together i.e. sulfate reduction and organic matter removal (SR-CR), autotrophic and heterotrophic denitrifying sulfide removal (A&H-DSR) and nitrification (AN) reactors. In this system, the operational parameters for successful bio-phase separation are sulfate and organic loading rate, hydraulic retention time (HRT), COD/SO42-ratio and pH for the SR-CR reactor, and sulfide and nitrate loading rate, HRT, pH, S2-/NO3-ratio and COD/NO3-for the A&H-DSR reactor. The results from a laboratory scale system demonstrated that for the SR-CR reactor, the optimal operating conditions were HRT≥24 h; sulfate and organic loading rate ≤7.5 kg SO42-/m3•d and ≤10 kgCOD/m3•d; COD/SO42-≥2; and pH ≥6.5. For A&H-DSR process, the optimal conditions are sulfide loading rate ≤6.0kg S2-/m3•d; nitrate loading rate ≤3.5 kg NO3-/m3•d; S2-/NO3-≥1; COD/NO3-≥1.25:1; and pH≥7.5. Under such conditions, high sulfate, ammonia and organic matter removal of 99%, 90% and 99% were achieved, respectively. In this case, the elemental sulfur (S0) reclamation efficiency reached 6.0 kg S0/m3•d, around 20 times higher than the maximum level as referred in the literatures. DGGE profiling indicated that the predominant functional organisms of Clostridiaceae sp., Desulfomicrobium sp., Methanosaeta sp. dominated in the SR-CR reactor, and Sulfurovum sp., Pseudomonas aeruginosa and Denitratisoma sp. in the A&H-DSR reactor. These species played essential role in metabolic functions in each bio-phase.

A pilot-scale test was conducted with an up-flow anaerobic sludge blanket (UASB) treating pharmaceutical wastewater containing berberine. The aim of this study was to investigate the performance of UASB in the condition of a high chemical oxygen demand (COD) loading rate from 4.64 to 8.68 kg/m3d and a wide berberine concentration from 254 to 536 mg/L, in order to provide a reference for treating the similar pharmaceutical wastewater containing berberine. The results demonstrated that the UASB average percentage reduction in COD and berberine 68.14% and 57.39%, respectively. Granular sludge was formed during this process. In addition, a model, built on the back propagation neural network (BPNN) theory and linear regression techniques was developed for the simulation of the UASB system performance in the biodegradation of pharmaceutical wastewater containing berberine. The average errors of COD and berberine were -0.55% and 0.24%, respectively. The results indicated that this model built on the BPNN theory was well-fitted to the detected data, and was able to simulate and predict the removal of COD and berberine by UASB reactor.

Bio-electrokinetic remediation of oil-contaminated soil is a promising technology. In this study, three bio-electrokinetic remediation experiments were carried out to study the effects of external addition of oil-degrading bacteria by electrokinetics and different operational parameters on oil decontamination in saturated soil. Results showed that oil in soil migrated from the anode towards the cathode with forward electroosmotic flow and accumulated near the cathode. Oil was barely degraded without external addition of oil-degrading bacteria. Although electrolytes were refreshed every 12 hr, soil pH varied greatly at the electrodes under unidirectional operation. When electrode polarity was reversed every 2 hr, soil pH was efficiently controlled within the range of 6.35-9.75. The relative oil concentrations after the bidirectional experiment were in the range of 0.81-0.84 after 20 days of treatment. The relatively low oil degradation rate may be due to the facultative aerobic environment in the saturated soil matrix.