Development Of A Novel Algal-bacterial Symbiotic Rotating Biological Contactor

At present, China lacks water seriously and water pollution is especially serious. Meanwhile, environmental protection and depleting crude oil supplies are becoming the overriding challenge faced by oil industries. Biodiesel has attracted considerable attention as a renewable, biodegradable, and nontoxic fuel. Autotrophic micro algae can utilize carbon dioxide which is from wastewater treatment as carbon sources and sunlight as the energy for oil accumulation which breaks a new path for bio-diesel industry. In this thesis, a novel wastewater treatment reactor, Algal-bacterial Symbiotic Rotating Biological Contactor, was developed. It was inoculated with an algal-bacterial consortium formed by the micro-algae and a mixed bacterial culture from an activated sludge process, to achieve organic compounds, nitrogen and phosphorus removal and algae recovery used as raw material for bio-diesel.Experiments were conducted on the bench-scale RBC. The changes of stages of Rotating Biological Contactor and inflow were investigated and optimized. Taking pollutant removal rate and algae growth rate as evaluation indexes, the operational aspects of the reactor before and after extended source were compared. The main conclusions of this issue including:1) The novel reactor based on biocontact oxidation and photo-bioreactor was construted, which consists of main body, cycle system, light source, membrane separation system, etc.2) By comparison the interrelated pollutant removal rates, the third stage RBC were not put into great play on the reactor operation, when hydraulic loading rate was 0.060m3/m2 h and HRT was7.2h. Considering the running cost, the bench-scale reactor was two stages instead of three. When hydraulic loading rate was 0.090m3/m2 h, effluent concentration of CODCr and NH4+-N met the standard of GB18918-2002 1A and SS, TN and TP met the standard of GB18918-2002 1B。Thus, 0.090m3/m2 h was the optimized hydraulic loading rate.2) After Scenedesmus dimorphus inoculation, the removal rates in terms of CODCr, SS, NH4+-N, TN and TP was not notability changed. Microalgae in the bioreactor grew slowly and ultimately cell concentration was low. Cleaning frequency of hollow-fiber membrane was about 30 days.4) By applied extended source, ultimately cell concentration was higher than bdfore and the time to reach the ultimately cell concentration was shorter. Significantly, TP and TN removal rates increased greatly, from 35.6% and 30.4% to 46.7% and 56.2% before membrane separation. Cleaning interval of hollow-fiber membrane in this period was about 26 days. Maximum algae biomass was 0.364g (dry weight) L-1d-1.5) After one-year bench-scale research work, the optimal operation controlling condition of the novel algal-bacterial symbiotic Rotating Biological Contactor was as follows through the comprehensive analysis: two stage RBC, influent flow=60L/h; HRT=4.8h; air flow rate=140L/h; algae recovery about 30 days .