沼液一体化综合处理与循环利用工艺

沼液过滤膜浓缩作为沼液处理的一个新方向,得到了广泛关注。该文将可堆肥处理的生物质材料秸秆作为滤料引入沼液的预处理,并对沼液过滤、膜浓缩及秸秆滤料堆肥效果进行了整体研究。研究结果表明,经过秸秆、火山岩、石英砂依次过滤后,可以去除沼液中95%以上的悬浮物,过滤后的秸秆经过简单晾晒,在含水率为75%的情况下,可以正常升温堆肥,高温期可以持续10 d,经过28 d堆置后基本达到腐熟要求,堆肥产品总养分含量接近5%,但含水率下降不明显。经过预处理的沼液进行超滤和纳滤之后,营养物质含量得到不同程度的提升,和未处理的原液相比,氮磷钾含量分别提升了2.6倍、1.9倍和4.5倍,Mg和Fe的浓缩倍数均达到10以上,氨基酸浓度提高了8.8倍,而且纳滤产生的透过液基本可以达到农田灌溉水水质标准。该研究结果为沼液的处理利用提供了参考。

Research on comprehensive integration process and recycling technologies of biogas slurry

Abstract: As a new direction for treating and utilizing the biogas slurry, the filtration and membrane concentration has received widespread attention in China. The corn stalk is a biodegradable recycled material that is good for composting. In this study, the corn stalk, combined with volcanics and quartz sand, were used as the pretreatment material for the filtration of biogas slurry. The filter materials were filled in different filters (10 cm in diameter and 1 m in height) connected in series through putting the corn stalk in the first filter, volcanics in the second one and the quartz sand in the last one, respectively. Using the ultrafiltration membrane and nanofiltration membrane for biogas slurry concentration, the effect of the filtration on membrane concentration was studied and then the possibility of composting the corn stalk was investigated. The results showed that, after filtrating through the corn stalk, volcanic rock and quartz sand successively, the content of suspended solids in the biogas slurry was reduced from 3830 (in initial) to 142 mg/L, with more than 95% of the removal rate of the suspended solids. In addition, the COD was decreased, while other parameters did not changed significantly. Since a great amount of suspended solids in the biogas slurry was intercepted after filtration, resulting an appropriate C/N ratio for composting, the corn stalk can be composted successfully even under the condition that the initial moisture content was 75%. During the composting process, the temperature increased normally and maintained approximately 10 d of high temperature. After 28 d of composting, the corn stalk could meet the requirements of maturity, with a 5% total nutrient (total nitrogen, phosphorus and potassium) and slightly changed moisture. After ultrafiltration and nanofiltration, in the concentrated solution the concentrations of the total nitrogen, phosphorus and potassium were increased by 2.6, 1.9 and 4.5 times, respectively, when compared with untreated biogas slurry. Additionally, the Mg/Fe ratio and the amino acid concentration were increased by more than 10 and 8.8 times, respectively. After membrane concentration, the fertilizer potential of the biogas slurry was improved greatly, and the permeate liquid of the nanofiltration could achieve basic requirement of the farmland irrigation water quality standards and livestock and poultry breeding industry pollutant discharge standards. Furthermore, although the ammonium nitrogen was exceed, the BOD5, COD, suspended solids, total phosphorus, fecal coliform, and the ova of roundworm could all meet the requirement of the both standards. After some special treatment for the ammonium nitrogen, the permeate liquid may be used as the irrigation water or drained directly. This study can provide a good reference for the treatment and utilization of biogas slurry.