基于城市污水资源化的微藻筛选与污水预处理

利用城市污水培养微藻,可在实现污水无害化处理的同时,培养微藻回收生物质能源.污水为微藻的培养提供氮、磷等营养组分和所需水源.由于城市污水含有大量的微生物,成分复杂,且不同藻种对污水的适应性与耐受性不同,因此,需要筛选出适宜于城市污水培养和高效产脂的藻种,并研究城市污水预处理方式,以使预处理后的城市污水更适于微藻的生长与产脂.本文根据课题组前期获得的藻种在城市污水中的生长与产脂情况以及对污水的净化能力筛选出适宜于城市污水培养的藻种.其中斜生栅藻(Scenedesmus obliquus)原始株与蛋白核小球藻(Chlorella pyrenoidosa)离子诱变藻株生物质与油脂产量较高,经污水培养后油脂产量分别可达0.43 g·L~(-1)、0.33 g·L~(-1),且含有较多的C16~C18脂肪酸,适宜于生物柴油的制备,同时可使培养后污水中COD、NH_4~+-N、TN、TP的去除率分别达到86.4%、100%、94.3%、93.4%和81.8%、100%、94.9%、94.2%.对可规模化扩大的污水预处理方式进行研究,发现不同藻种所最适的污水预处理方式不同.对于耐污性能较强的斜生栅藻原始株,除去粗大悬浮物后的城市污水即可用于其培养.对于蛋白核小球藻诱变株,城市污水经沉淀、过滤联合预处理后适宜于其培养.

Selection of Microalgae for Biofuel Using Municipal Wastewater as a Resource

Cultivating microalgae using municipal wastewater can achieve not only treatment of the wastewater but also recovery of algae for use as a biofuel energy source. Wastewater provides necessary nutrients, such as nitrogen and phosphorus, and water for microalgal growth. Because of the complexity of components of municipal wastewater, variety of adaptability, and tolerance to wastewater of different microalgal species, it is necessary to select a suitable microalgal species with high performance in lipid production and identify proper pretreatment of the wastewater to achieve high lipid production using municipal wastewater for algal biofuel production. Based on microalgal growth, lipid production, and clean-up performance of wastewater, we selected Scenedesmus obliquus wild strain and Chlorella pyrenoidosa mutant by ion beam implantation from a test group for the biofuel production. Laboratory test results showed that S. obliquus wild strain and C. pyrenoidosa mutant had respective lipid productions of 0.43 g·L^-1 and 0.33 g·L^-1, with more C16-C18 fatty acids, which were suitable for biodiesel production. The pollutant removals from the wastewater by S. obliquus wild strain and C. pyrenoidosa mutant were COD, 86.4% vs. 81.8%; NH₄⁺-N, 100.0% vs. 100.0%; TN, 94.3% vs. 94.9%; and TP, 93.4% vs. 94.2% respectively. The two different microalgal strains required different pretreatments. After removal of large particles, the raw wastewater could be directly used for the cultivation of S. obliquus wild strain. To grow C. pyrenoidosa mutant with municipal wastewater, pretreatment procedures including precipitation followed by filtration should be employed.