Chunmao Chen

Bioremediation of Crude Oil Contaminated Soil

A laboratory study was undertaken to bioremediation crude oil contaminated soil by isolated strains. Pseudomonas strain A as the most superior indigenous biodegrader was selected. At the optimal growth condition of pH 7 and with 5 g/L NaCl, cosubstrate α-lactose, and inorganic salt FeSO4, 82.3% of crude oil degradation efficiency was obtained. Furthermore, characteristics of chemical composition during the biotreatment indicated that saturation hydrocarbons and some aromatics were effectively removed by strain A. N-alkane in crude oil was preferentially degraded, especially those in the range of nC16–nC24. Biodegradation of aromatics depended on benzene ring numbers and complexity of structures.

A comprehensive evaluation of re-circulated bio-filter as a pretreatment process for petroleum refinery wastewater

Conventional biological treatment process is not very efficient for the treatment of petroleum refinery wastewater (PRW) that contains high-concentration of organic contaminants. Prior to biological treatment, an additional pretreatment process for PRW is required for the effluent to meet the discharge standards. While re-circulated bio-filter (RBF) has been applied as a pretreatment process in several PRW treatment plants, its effects have not been comprehensively evaluated. In this study, the parameters of operation, the changes in pollution indexes and contaminant composition in an engineered RBF have been investigated. We found that mainly highly active de-carbonization bacteria were present in the RBF, while no nitrification bacteria were found in the RBF. This indicated the absence of nitrification in this process. The biodegradable organic contaminants were susceptible to degradation by RBF, which decreased the Biological Oxygen Demand (BOD5) by 83.64% and the Chemical Oxygen Demand (CODCr) by 54.63%. Consequently, the alkalinity and pH value of RBF effluent significantly increased, which was unfavorable for the control of operating parameters in subsequent biological treatment. Along with the decrease of CODCr, the RBF effluent exhibited a reduction in biodegradability. 834 kinds of recalcitrant polar organic contaminants remained in the effluent; most of the contaminant molecules having complex structures of aromatic, polycyclic and heterocyclic rings. The results of this study showed that RBF could efficiently treat PRW for biodegradable organic contaminants removal; however, it is difficult to treat bio-refractory organic contaminants, which was unfavorable for the subsequent biological treatment process operation. An improved process might provide overall guarantees for the PRW treatment.

Refining wastewater treatment using EGSB-BAF system

AbstractThe performance of an expanded granular sludge bed (EGSB) in combination with a biological aerated filter (BAF) system for petroleum refining wastewater treatment was investigated. The system was monitored for two months at a hydraulic retention time of 17.5 h and a digestion temperature of 34 ± 1°C. The results showed that the total chemical oxygen demand (CODCr) and oil removal efficiencies were up to 90 and 87%, respectively, with the average CODCr and oil concentrations of 85 and 11 mg/L in the system effluent. Moreover, almost 97% of suspended solids (SS) were removed by the system and the effluent SS concentration was only 15 mg/L. The sludge yield coefficient of 0.0036 mg/mgCODCr showed a low excessive sludge production for the EGSB reactor. The excellent treatment performance indicated that this EGSB-BAF system could be appropriate for refining wastewater treatment. Besides, methane yield was only about 0.21 mLCH4/mgCODCr in the EGSB reactor, lower than the theoretical yields. The poor met...

Biodegradability evaluation of pollutants in acrylonitrile wastewaters based on particle size distribution

AbstractAcrylonitrile wastewaters (ANWs) treatment is a big trouble for chemical fiber industry in China, and there was not yet an effective biological treatment technology for ANWs due to the lack of detailed analysis on the biodegradability of pollutants. In this work, two typical point-source ANWs, acrylonitrile synthesis wastewater (ANSW), and acrylonitrile polymerization wastewater (ANPW) were fractionated by gradient membrane separation method based on the pollutants particle size distribution (PSD). Moreover, biochemical oxygen demand/chemical oxygen demand (COD) ratios, oxygen uptake respirometric tests, dehydrogenase activity tests, and simulated aeration tests were integrated to evaluate the biodegradability of PSD-based pollutants in ANWs. The results showed that most COD were from dissolved fractions in both of ANSW and ANPW. For ANSW, the soluble fractions had greater biodegradation potential than particulate and colloidal fractions. Colloidal fractions are easier to be biodegraded than parti...

Simultaneous bioelectricity generation and biodegradability improvement of refinery wastewater using microbial fuel cell technology

AbstractWastewater contains abundant chemical bond energy that can be recovered by microbial fuel cell (MFC), so the aim of this study was to explore the feasibility of using MFC technology to dispose refinery wastewater and generate electricity simultaneously by recycling the chemical energy in wastewater. The energy recovery rate together with the wastewater treatment performance of MFCs with different structures was studied, respectively. Results indicate that both the single- and double-chambered MFC could be successfully started up to generate electricity, using refinery wastewater as fuel, the highest voltage output of two-chambered MFC was 305 mV, and the relevant maximum power density output was 310.08 mW/m3. Meanwhile, the maximum coulombic efficiency of refinery wastewater was 3.0%. Refinery wastewater treatment efficiency of MFCs was higher than that of traditional anaerobic biological treatment process. The oil pollutant removal rate of double-chambered MFC could reach to as high as 83.60%. In...