Field experiment on biological contact oxidation process to treat polluted river water in the Dianchi Lake watershed

In this study two types of biological contact oxidation processes(BCOP),a step-feed(SBCOP)unit and an inter-recycle(IBCOP)unit,were designed to investigate the treatment of heavily polluted river water.The Daqing River,which is the largest pollutant contributor to the Dianchi Lake,one of the most eutrophic freshwater lakes in China,was taken for the case study.It was found that the SBCOP had higher adaptability and better performance in the reduction of COD,TN,and TP,which made it applicable for the treatment of polluted river water entering the Dianchi Lake.Nitrification rate was observed to be greatly affected by the influent temperature.During each season,the nitrification in the SBCOP was higher than that in the IBCOP.TN removal efficiency in the SBCOP was higher than that in the IBCOP during the winter and spring but poorer during the summer,possibly due to the inhibition of denitrification by higher dissolved oxygen level in the summer.Moreover,symbiotic algaebacteria growth may be conducive to the removal of pollutants.

Biodegradation of Lubricating Oil in Wastewater with Zoogloea sp.

The purpose of this study was to identify microbial strains that have a strong ability to biodegrade lubricating oil. No. 20 lubricating oil was used as the sole carbon source in an isolation medium to screen bacteria from sludge that had been contaminated with crude oil. Through both morphological and biochemical methods, the bacterial strain that had the highest biodegrading capacity was identified as Zoogloea sp. On the basis of these preliminary results, a biological contact oxidation method was employed to further assess the ability of the Zoogloea sp. strain to treat wastewater contaminated by No. 20 lubricating oil using three oxidation cabins and two hydraulic retaining times （HRT）. Results showed that the concentration of No. 20 lubricating oil with a 12 h hydraulic retaining time and 16.5 L h^-1 inflow rate was reduced by 99.3% in 15 d, and with a 6 h hydraulic retaining time and 33 L h%^-1 inflow rate it decreased by 98.6070 in 12 d. The results from this study indicated that Zoogloea sp. had a strong potential to be utilized in biodegradation of lubricating oil.

Comparison and modeling of two biofilm processes applied to decentralized wastewater treatment

In order to control water pollution in the rapidly urbanizing South China area,biological contact oxidation(BCO)process and biological aerated filter(BAF)process were applied in a pilot-scale experiment for decentralized wastewater treatment.An investigation to find the optimal parameters of the two biofilm systems was conducted on hydraulic loading,organic loading,and aeration rate.The results indicated that the water reuse criteria required a maximum hydraulic and organic loading of 30.0 m^(3)/(m^(2)·d)and 4.0 kg COD/(m^(3)·d),respectively,as well as a minimum effluent DO of 4.0 mg/L.The utilization of a new media allowed BAF to perform better than BCO.The kinetic description of the COD removal process for BAF and BCO are Se=S0e^(-0.639t)/(1+1.035t),and S_(e)=S_(0)/[(1+0.947t)(1+1.242t)],respectively.The correlativity analysis showed that the two models could predict the effluent water quality based on the hydraulic retention time.Thus,the appropriate hydraulic loading for certain effluent water quality demands could be determined.The two models could be applied to wastewater treatment practice.