生物沥浸法去除猪粪中重金属和提高其脱水性能研究

Removal of heavy metals and dewaterability of pig slurry facilitated by bioleaching

采用复合嗜酸性硫杆菌,通过摇瓶试验研究了不同Fe2+添加量下生物沥浸对含固率为3%的猪粪中重金属的去除和脱水性能的影响.同时,考察了不同处理的pH、氧化还原电位(ORP)、Fe2+、Fe3+、总Fe、Cu、Zn、比阻和毛细吸水时间(CST)的变化.结果表明,采用生物沥浸技术能有效地去除猪粪中的重金属,随着Fe2+添加量的增加,猪粪中重金属的去除率呈上升趋势,其中,4g·L-1Fe2++2g·L-1S0+接种嗜酸性硫杆菌的处理效果最好,沥浸结束后对Cu和Zn的去除率分别达到了87.3%和91.9%,重金属Zn先于Cu从猪粪中溶出.研究发现,沥浸结束后,猪粪的比阻和CST与原始猪粪相比大幅度降低,且随着Fe2+添加量的增加其脱水性能也得到提高,在添加2g·L-1S0和接种嗜酸性硫杆菌的情况下,添加4g·L-1Fe2+和5g·L-1Fe2+的处理,其脱水性能较原始猪粪分别提高了117和205倍.采用生物沥浸技术处理猪粪,可去除其中的重金属,改善其脱水性,提高猪粪资源化再利用的价值,这为猪粪的资源化利用提供了一种全新的途径.

Removal of heavy metals and dewaterability of pig slurry during bioleaching were investigated through batch experiments with co-inoculation of two acidophilic thiobacilli （Acidithiobacillus thiooxidans TS6 and Acidithiobacillus ferrooxidans LX5） and the addition of Fe^2＋ as energy source. During bioleaching,dynamic changes of pH,ORP,Fe^2＋,Fe^3＋,total Fe,Zn,Cu,and dewaterability （expressed as specific resistance γ or Capillary Suction Time CST） of pig slurry were monitored periodically. Results showed that bioleaching process could solubilize pig slurry-borne heavy metals. Moreover,higher addition of Fe^2＋ led to higher removal efficiency of heavy metals. The treatment with 4 g·L^-1 Fe^2＋＋2 g·L^-1 S0 ＋ bacterial inoculation could achieve the highest metal removal efficiency of 87.3% Cu and 91.9% Zn after 96 h bioleaching. Pig slurry-borne Zn was more easily solubilized than Cu. In addition,the two measured indexes for slurry dewaterability,specific resistance γ and CST of bioleached pig slurry were reduced drastically compared to original pig slurry. Higher Fe^2＋ levels produced slurry with better dewaterability. Bioleached pig slurry dewaterability was increased 117 and 205-fold under the treatments of 2 g·L^-1 S0＋ 4 g·L^-1 Fe^2＋ and 2 g·L^-1 S0＋ 5 g·L^-1 Fe^2＋,respectively. It was concluded that bioleaching could not only greatly enhance dewaterability of pig slurry,but simultaneously improve the removal of heavy metals. This study might provide a new approach for treatment and disposal of pig slurry.