吹脱与鸟粪石沉淀组合工艺处理中温厌氧发酵沼液研究

利用吹脱+鸟粪石沉淀(MAP)组合工艺处理中温厌氧发酵沼液。研究发现沼液吹脱的最佳工艺参数为:p H值为10,吹脱时间8 h,气液比2 400,并添加填料,此时沼液中氨氮去除率在90%左右。吹脱后的沼液p H值在9.2左右,在MAP沉淀法的适宜p H值附近,不需再进行p H值调节,可节约药剂成本。经MAP沉淀处理后的沼液出水氨氮和总磷去除率分别达到了95%和80%。COD和SS去除率分别在40%和32%左右。MAP沉淀出水的p H值在8.3左右,可满足生化处理的进水要求。同时,MAP沉淀处理后的出水C/N比大大提升,从0.7上升到了10,有利于后续生化系统的进一步处理。该工艺既可使沼液得到净化处理,又可回收其中的营养物质。

Treatment of Liquid Digestate by Stripping Combined with Struvite Precipitation

Stripping combined with struvite precipitation (MAP) was used to treat the liquid digestate. The results showed that the best process parameters for stripping of the digestate from mesophilic digestion were as follows: the pH value was 10, stripping time was 8 h, gas-liquid ratio was 2 400, and filler was added. The removal rate of ammonia in the digestate was about 90%. The pH value of the digestate after stripping was about 9.2 and it was suitable for MAP precipitation method. The pH value regulation was not necessary, so it can save the cost of dosage. The removal rate of ammonia nitrogen and total phosphorus were 95% and 80%, respectively, after MAP precipitation treatment. The removal rates of COD and SS were 40% and 32%, respectively. The pH value of the effluent after MAP precipitation was about 8.3, which can meet the requirements of biochemical treatment. Meanwhile, C/N ratio of the effluent was greatly improved, which was increased from 0.7 to 10, and it was conducive to further treatment of the follow-up biochemical system. The process not only makes the digestate be processed, but also can recover the nutrients.