产絮凝剂菌种的筛选及其在猪场污水净化中的应用

分离高效絮凝剂产生菌以有效絮凝猪场污水中的悬浮物。通过稀释平板法和筛选培养基及以发酵液对猪场污水的絮凝率为指标复筛,从猪场污水沉淀池污泥中筛选获得一株产絮凝剂的细菌FD-14,并进行16S r DNA鉴定,然后以絮凝效果为标准,采用La(34)正交设计对其培养条件进行优化;采用单因素试验对其碳氮源进行优化。以最优培养条件下菌株的发酵液实际絮凝猪场污水,与化学絮凝剂的絮凝效果进行比较。分离得到一株高效絮凝剂产生菌FD-14,分子生物学鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens),其产絮凝剂最适条件为温度33℃,p H值6.6,转速150 r/min,培养时间42 h。菌株FD-14利用淀粉作为其廉价碳源替代发酵培养基的絮凝率为80.80%,与原标准培养基差异不显著(P0.05);对猪场实际应用结果表明,微生物絮凝剂和化学絮凝剂对猪场污水絮凝率分别为79.0%和62.7%,微生物絮凝剂比化学絮凝剂对猪场污水絮凝率高16.3%。解淀粉芽孢杆菌FD-14是生物絮凝剂高效产生菌,其产生的絮凝剂可用于猪场污水悬浮物絮凝。

Isolation and identification of flocclant producing strain and its application for swine wastewater clarification

An efficient flocculant producing strain was isolated, which could effectively flocculate suspended matter in piggery wastewater. The sludge from piggery sewage sedimentation tank was selected as the screening material. Screening was carried out by dilution plate method and screening medium. Colonies with smooth, large and sticky surfaces were selected. Then the plate was used to isolate and purify the strain, and then inoculated into the liquid medium. The flocculation rate of swine wastewater treated by bacterial fermentation liquid as index was rescreened. Finally, a flocculant producing bacterial strain FD-14 was obtained and identified by 16S rDNA. First, single factor experiments were conducted on the culture conditions, in order to determine the influence of 4 factors on the flocculation activity, such as culture temperature, pH value, rotational speed and time, L9 (34) orthogonal design was used to optimize the culture conditions of the strain. The culture conditions were optimized: Temperature: 30, 33 and 36℃; pH vale: 6.6, 7, 7.4; speed: 120, 150, 180 r/min, and incubation time: 42, 48, 54 h. Then the single factor experiment was used to optimize the carbon and nitrogen source of the medium. By using ultraviolet spectroscopy, infrared spectroscopy, phenol sulfuric acid method and Coomassie brilliant blue method was used to analyze the components of flocculant. Under the optimal conditions, strain FD-14 was cultured and fermentation broth was used as a crude flocculant, which had been applied to practical swine farm wastewater treatment. The results showed that FD-14 was identified asBacillus amyloliquefaciens based on 16S rDNA gene sequencing. The optimum culture conditions of strain FD-14 were 33℃, initial pH value 6.5, rotational speed of 150 r/min, and 42 h incubation. The results showed that strain FD-14 could use starch as an alternative inexpensive carbon source for the fermentation medium, the flocculation rate of 80.80% was not significantly different (P>0.05) from the original standard medium. The effect of substituting inexpensive nitrogen sources was poor; the flocculation rate of the best, ammonium chloride, was 67.38%, which was significantly less than the original standard medium (P<0.05). According to the practical application results on a swine farm, the flocculation rates of the microbial and chemical flocculants of the swine farm wastewater were 79.0% and 62.7%, respectively. The flocculation rate of the microbial flocculant was 16.3% higher than that of the chemical flocculant. Analysis using UV and IR spectroscopy, the phenol sulfuric acid method, and the Coomassie brilliant blue method of flocculant composition revealed that the polysaccharide flocculant was rich in hydroxyl and carboxyl groups. Strain FD-14 mainly secreted 65.96% polysaccharide substances, but the protein content was minimal, so it had strong heat stability. In this study, it could be concluded that bioflocculant-producing bacteria with high flocculating activity and flocculation might be used for flocculation of swine farm wastewater.