| Microalgae has good tolerance to different concentrations of wastewater,and can obtain high value-added products in the process of wastewater treatment.Unlike traditional wastewater treatment technology and high-end treatment facility,the treatment by microalgae is excepted to realize "Break even" in the process of wastewater treatment.Microalgae is not only easy to culture,in the process of wastewater treatment can also reduce carbon emissions.Many studies have shown that treatment of microalgae in synthetic wastewater or in laboratory conditions,both for small volume of wastewater has a better treatment effect,but there is still a big gap between these studies and the industrialization of microalgae for wastewater treatment.Chlorella zofingiensis,which is selected in this paper,not only has good tolerance and rapid growth,but also has strong absorption of nitrogen and phosphorus.This paper studied the effect of large-scale treatment of tailwater and municipal wastewater under outdoor natural light conditions,and investigated the oil production capacity of Chlorella zofingiensis in wastewater treatment and its potential application to urban wastewater treatment and industrialization was evaluated comprehensively.The main research contents and results are as follows:(1)The optimization of C.zofingiensis growth conditions is concluded that the growth of chlorella inoculation OD was 1.2,ventilation of 1L·min-1,and when the thickness of the photobioreactor was 1 cm,the removal efficiency of total nitrogen and total phosphorus was 96.6% and 97.7%,respectively.(2)In outdoor large-scale flat-panel photobioreactor for effluent from activated sludge process by batch culturing C.zofingiensis.The TP concentration in the summer experiment could be treated to 0.06 mg·L-1 removal rate of 78.96%,and the total phosphorus treatment in winter was 0.29 mg·L-1,removal rate of 87.64%,the removal rate of COD was 72.13% and 66.74%,respectively.The highest 0.43g·L-1 biomass could be obtained,and the oil content was 25.57%.(3)In outdoor large-scale flat-panel photobioreactor for municipal wastewater by batch culturing C.zofingiensis.The final removal rate of NH4+-N in the spring and summer experiments was 94.05% and 99.86% respectively,the final TN removal rate was 91.73% and 99.73%,the removal rate of COD were 86.55% and 78.72%,the removal rate of BOD5 were up to 89.87% and 83.38% respectively.There was a significant increase in total nitrogen removal from municipal wastewater,compared with that of tail water,because of sufficient carbon source in raw municipal wastewater.(4)In order to improve the removal rate of organics by C.zofingiensis,aerobic bacteria in activated sludge was added in C.zofingiensis to construct algae-bacteria consortium,and the algae-bacteria symbiosis experiment has been carried out according to the different proportion of algae and bacteria,the growth of C.zofingiensis in algae-bacteria symbiosis system has been determined to the optimum mixing ratio was algae: bacteria =10:1;experiment with algae-bacteria mixing ratio of 10:1 to treat raw water has been done in lab,the NH4+-N removal rate up to 96.61%,the TN removal rate was 85.16%,the TP treatment rate was 95.87% in 24 h,and the highest biomass yield was 0.92g·L-1.(5)In outdoor large-scale flat-panel photobioreactor for municipal wastewater by batch culturing algae-bacteria consortium,and has been compared with the treatment of the wastewater by the independent Chlorella treatment system.The experimental results have been showed that NH4+-N removal rate reached 96.61%,the TN treatment rate was 85.16%,TP treatment rate reached 95.87%,and compared to the independent system of Chlorella could get better effect in removing nitrogen and phosphorus in a short period of time,at the end of the experiment could harvest dry matter 0.45g·L-1.Chlorella zofingiensis can not only deal with the effluent from activated sludge process can also have a good effect on the raw municipal wastewater under different climatic conditions.Compared with Chlorella zofingiensis,algae-bacteria consortium treatment can be better in the same treatment time.Chlorella zofingiensis in the application of wastewater treatment has great potential. |
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