不同微藻培养处理下餐厨垃圾沼液氨吹脱剩余液净化效果研究

Purification Effects of Ammonia Stripping Residual Liquid from Anaerobic Digestion Food Effluent by Two Microalgae Cultivation

摘要:

餐厨垃圾沼液富含丰富的营养物质，沼液经过氨氮吹脱后的剩余液仍然含有大量的氮磷养分，是微藻培养潜在的优质培养基。选取小球藻和四尾栅藻两种微藻为研究对象，对餐厨垃圾沼液氨吹脱后的剩余液（本文中称为“氨吹脱沼液”）进行微藻培养处理，研究其在不同浓度沼液 （质量分数20%、40%、60%、80%和100%） 中的生长特性、对沼液中污染物净化效果以及胞外聚合物的分泌情况。研究结果显示，两种微藻在中低浓度沼液（质量分数40%～60%）中生长状态良好，小球藻在质量分数 40% 的沼液中可获得最高生物量 1.0 g/L，四尾栅藻在沼液质量分数为60%时获得最大生物量0.9 g/L，但是在高浓度沼液（质量分数80%～100%）中微藻生长受到一定抑制，氮磷的去除效果降低。利用中低浓度沼液（质量分数20%~60%）培养小球藻和四尾栅藻时，对总氮、硝态氮、总磷和化学需氧量的去除效果较好，小球藻对应的去除率最高分别为41.14%、48.64%、77.70% 和 62.08%;四尾栅藻对应的去除率最高分别为59.10%、58.39%、82.65%和63.43%，高于小球藻。经过胞外聚合物分析，发现随着培养时间的延长，微藻的胞外聚合物含量先增加后减少;小球藻在40%沼液中含量最高，而四尾栅藻在80%沼液中含量最高，且通过三维荧光光谱分析发现，胞外聚合物主要有机物为溶解性微生物副产物和富里酸。因此，综合考虑微藻生物量、氮磷养分去除效率和沼液稀释成本，四尾栅藻在餐厨垃圾沼液处理中表现出较高的适应性。

Abstract:

Anaerobic digestion food effluent （ADFE） is rich in nutrients, and the residual liquid after ammonia stripping still contains a large amount of nitrogen and phosphorus nutrients, making it a potential high-quality culture medium for microalgae cultivation. Two microalgae，Chlorella sp. and Scenedesmus quadricauda（S. quadricauda）, were selected as the objects of study, and the residual liquid after ammonia stripping of ADFE （referred to as “ammonia stripping digestate”） was cultured，and the growth characteristics, purification effect of pollutants and secretion of extracellular polymers （EPS） were investigated in the digestate at different concentrations （20%，40%，60%，80% and 100%）. The results showed that both microalgae species grew well in medium to low concentrations of digestate （40%~60%）. Chlorella sp. achieved the highest biomass of 1.0 g/L in 40% concentration of ammonia stripped digestate, while S. quadricauda obtained the maximum biomass of 0.9 g/L at a 60% concentration. However, in high concentrations of digestate （80%~100%）, the growth of microalgae was somewhat inhibited, and the removal efficiency of nitrogen and phosphorus was decreased. When cultivating Chlorella sp. and S. quadricauda with medium to low concentrations of digestate （20%~ 60%）, the removal effects on total nitrogen, nitrate nitrogen, total phosphorus, and chemical oxygen demand （COD） were the best. The highest removal rates for Chlorella sp. were 41.14%，48.64%，77.70%, and 62.08%, respectively;while for S. quadricauda, the highest removal rates were 59.10%，58.39%，82.65%, and 63.43%, which were higher than those of Chlorella sp. Analysis of EPS also revealed that the content of EPS in microalgae was firstly increased and then decreased with extended cultivation time. Chlorella sp. had the highest content in 40% digestate, whereas S.quadricauda had the highest content in 80% digestate. Furthermore, three-dimensional fluorescence spectroscopy analysis indicated that the main organic components of EPS were soluble microbial byproducts and fulvic acids. Therefore, considering the microalgal biomass, nitrogen and phosphorus nutrient removal efficiencies, and the cost of digestate dilution，S. quadricauda showed high adaptability in ADFE treatment. The research result can provide insights into the sustainable management and resource utilization of digestate.