动态中温厌氧消化液进行鸟粪石回收磷的试验研究

Recovery of Phosphorus from Dynamic Mesophilic Anaerobic Digestion Supernatant of Sewage Sludge

磷元素是一种十分宝贵的矿产资源,面临着日益短缺的局面,而采用活性污泥法工艺会产生大量富含氮磷的剩余污泥。通过在实验室搭建连续式进泥的动态中温厌氧消化处理污泥系统,探究利用鸟粪石结晶法回收系统产出的厌氧消化液中氮磷的优化反应条件,可为实际生产中厌氧消化液的氮磷资源化工艺参数设计提供理论依据。动态试验分为第Ⅰ阶段(氮磷物质的量之比为5.4∶1)和第Ⅱ阶段(氮磷物质的量之比为7.8∶1),当镁磷物质的量之比为1.1∶1时,初始消化液(不加碱液)p H值在7.7以上,鸟粪石纯度可以达到84%。通过投加碱液调节p H值后,消化液的氮磷去除率会随着p H值上升而增高,而鸟粪石纯度并没有明显变化。

Phosphorus is one of the very valuable natural resources, which is becoming less and less nowadays. As the by-product of activated sludge process, excess sludge contains lots of nitrogen and phosphorus. The research was based on a lab-scale dynamic mesophilie anaerobic digestion system with continuously adding of sludge, which made a large release of nitrogen and phosphorus into the superna- tant. The optimum conditions of phosphorus recovery by struvite precipitation from anaerobic digestive ef- fluent were investigated to provide a theoretical basis for the design of process parameters for recycling ni- trogen and phosphorus in anaerobic digestion supernatant. The experiment was divided into two stages： the molar ratio of N/P was about 5.4 ： 1 in stage Ⅰ , and 7.8 ： 1 in stage Ⅱ. When the initial pH of su- pernatant without adding alkali was over 7.7, and Mg/P molar ratio was 1.1 ： 1, the purity of struvite could reach 84%. After adding alkali to adjust pH, the removal rates of phosphorus and nitrogen were increased with the increase of pH, but the purity of struvite did not change much.