响应面法优化藻菌共生体系深度处理畜禽养殖废水工艺研究

Optimization of microalgae-bacteria symbiosis system for the advanced treatment of livestock wastewater using response surface methodology

为优化微藻-细菌共生体系对畜禽养殖废水中碳氮磷去除的参数条件,利用响应面分析法(Response surface methodology,RSM)中的Box-Behnken中心组合设计(BBC),以接种比例、曝气量以及初始氨氮浓度为试验变量,以污染物去除率为响应值开展试验。响应面分析结果表明,对于COD去除的最佳条件为:活性污泥与微藻接种比例为6.0(m/m)、曝气量2.0 L·min^-1、初始氨氮浓度750 mg·L^-1,此时COD去除率达92%以上。对于总氮(Total nitrogen,TN)的去除,当接种比例5.0(m/m)、曝气量1.5 L·min^-1、初始氨氮浓度750 mg·L^-1时,其去除率可达最大值(53%)。而对于磷酸盐的去除,当接种比例6.0(m/m)、曝气量1.5 L·min^-1、初始氨氮浓度600 mg·L^-1时,试验前96 h内便可达到100%的去除率。进一步对生物量检测发现,初始条件分别为曝气量1.5 L·min^-1、初始氨氮浓度900 mg·L^-1、接种比例4.0(m/m)或曝气量1.0 L·min^-1、初始氨氮浓度750 mg·L^-1、接种比例4.0(m/m)时,微藻生物量产量最高,可达到1.63~1.64 g·L^-1。研究表明,通过响应面法可以优化藻菌共生体系对畜禽养殖废水的处理工艺。对于不同的目标污染物,具有不同的最优参数组合。综合考虑各因素对各目标污染物去除效果的影响,可以选择废水处理工艺最优参数组合。通过回收在废水处理过程中生长的藻菌共生体用于后续生物质利用,可实现良好的经济价值,提高该工艺在污水深度处理中的应用前景。

In order to achieve the optimized parameters for nutrient removal from livestock wastewater using the microalgae-bacteria symbiosis system,the Box-Behnken central combination design(BBC)of response surface methodology(RSM)was used.The selected experimental variables were inoculation proportion(IP),aeration rate(AR),and initial ammonium nitrogen(NH+4-N)concentration and the response value was pollutant removal efficiency(RE).The results of RSM showed that the optimal conditions for chemical oxygen demand(COD)removal were:activated sludge to microalgae IP at 6.0(m/m),AR at 2.0 L·min^-1 and initial NH+4-N concentration of 750 mg·L^-1with the highest COD RE over 92%.For total nitrogen(TN)removal,the best RE of 53%was achieved when IP was 5.0(m/m),AR was 1.5 L·min^-1,and initial NH+4-N concentration was 750 mg·L^-1.For phosphate removal,the RE reached 100%in 96 h with the IP at 6.0,the AR at 1.5 L·min^-1,and the initial NH+4-N concentration of 600 mg·L^-1.Further testing on biomass production showed that the highest yield of microalgae(1.63~1.64 g·L^-1)was achieved with AR at 1.5 L·min^-1,initial NH+4-N concentration of 900 mg·L^-1,and IP at 4.0(m/m)or AR at 1.0 L·min^-1,initial NH+4-N concentration of 750 mg·L^-1,and IP at 4.0(m/m).The results showed that RSM could be utilized for the optimization of livestock wastewater treatment by the microalgae-bacteria symbiosis system.There were different optimal parameter combinations for different targeted pollutants.Considering all parameters that influence the pollutant REs,the optimized parameter combination can be selected.The microalgae-bacteria consortia harvested from the wastewater treatment process can be further utilized as biomass resources,which will bring good economic value and further raise the application prospects of the process.