Abstract:

Microalgae are important chemical raw materials, which contain proteins, lipids, β-carotenoids and vitamins, et al.. Using domestic sewage to cultivate microalgae can reduce the cost of microalgal products and achieve sewage treatment at the same time. In this study, three common industrial microalgae, Scenedesmus obliquus, Chlorella vulgaris and Spirulina sp., were used to dispose the low, medium and high simulated domestic sewage. Microalgal density, water treatment effects and the role of microalgae in nitrogen and phosphorus removal process were studied. Results showed that in the low concentration domestic sewage, both Scenedesmus obliquus and Chlorella vulgaris could maintain good growth status and the biomass of Chlorella vulgaris was higher than that of Scenedesmus obliquus. Scenedesmus obliquus grew better compared to Chlorella vulgaris in medium and high concentration of domestic sewage. However, Spirulina sp. died in the middle and late stages in all domestic sewage, indicating a bad fouling resistance ability. This indicated that the selected microalgae are not ideal for the treatment of medium and high concentration domestic sewage, but have better treatment effects for low concentration domestic sewage. During day 6-7, the removal rates of SRP and NH₄⁺-N in the low concentration domestic sewage were 82.34%, 85.67%, 56.52% and 52.16%, 61.86% 36.00% for Scenedesmus obliquus, Chlorella vulgaris and Spirulina sp., respectively. Scenedesmus obliquus and Chlorella vulgaris could remove both nitrogen and phosphorus effectively in low concentration sewage. Material balance results showed that after 9 days, the TCP increased by 0.66 mg∙L^-1, 0.91 mg∙L^-1 and 0.59 mg∙L^-1 in the low mass concentration group, respectively, indicating microalgae converted dissolved phosphorus to granular phosphorus in wastewater, which may be the main way to remove phosphorus. NH₄⁺-N decreased in all groups, while TCN increased for microalgae assimilated NH₄⁺-N into organic nitrogen. NO₂^--N did not occur during the experiment, indicating that the denitrification of NH₄⁺-N was assimilation instead of nitrification and denitrification. In conclusion, low and medium concentration of domestic sewage could be used in the cultivation of Scenedesmus obliquus and low concentration domestic sewage could be suitable in the cultivation of Chlorella vulgaris. And both algae had high nitrogen and phosphorus removal effect on sewage treatment.

Key words: domestic sewage, microalgae biomass, nitrogen removal, phosphorus removal, nitrogen conversion, phosphorus conversion

摘要：

微藻含有丰富的蛋白质、油脂、β-胡萝卜素和维生素等高价值营养成分,是重要的化工原料。利用含氮、磷和有机物的生活污水培养微藻可有效降低微藻高价值产品的生产成本,同时达到处理污水的目的。为此,以3种常见的产业微藻斜生栅藻（S. obliquus）、普通小球藻（C. vulgaris）和螺旋藻（Spirulina sp.）为研究对象,研究其在低、中、高浓度模拟生活污水中的生长情况及对污水的处理效果,并通过物料衡算探究其在氮、磷形态转化过程中的作用。结果表明：低浓度模拟生活污水中,斜生栅藻和普通小球藻均能维持较好的生长状态且普通小球藻生物量高于斜生栅藻;中、高浓度模拟生活污水中,斜生栅藻生长较好但普通小球藻生长状态较差,后期死亡;螺旋藻在低、中、高浓度的模拟生活污水中后期均出现死亡现象,表明其耐污能力较差。3种微藻对中、高浓度模拟生活污水的处理效果均不理想,但对低浓度污水处理效果较好。第6—7天,斜生栅藻、普通小球藻和螺旋藻对低浓度模拟生活污水中溶解性活性磷SRP的去除率分别为82.34%、85.67%和56.52%,对NH₄⁺-N去除率分别为52.16%、61.86%和36.00%。表明斜生栅藻和普通小球藻能够有效地去除低浓度生活污水中的氮、磷物质。物料衡算结果显示,9天后,低质量浓度组胞内总磷TCP分别增加了0.66、0.91、0.59 mg∙L^-1,表明微藻将污水中溶解态磷向颗粒态磷转化,这可能是去除污水中磷的主要途径;各浓度组NH₄⁺-N均有减少,而胞内总氮TCN呈增加趋势,这是因为微藻将NH₄⁺-N同化为有机氮。实验过程未发现NO₂^--N的存在,表明微藻脱氮是直接吸收NH₄⁺-N,并非通过硝化和反硝化过程完成。研究结果表明,低、中浓度生活污水可用于斜生栅藻的产业化养殖,低浓度生活污水可用于普通小球藻的产业化养殖,且均对污水具有较高的脱氮除磷效果。

关键词: 生活污水, 微藻生物量, 脱氮, 除磷, 氮转化, 磷转化