不同生物炭对水产养殖尾水中磷的去除研究

Removal of phosphorus from aquaculture tailwater by different biochars

磷超标的水产养殖尾水易导致受纳水体富营养化,而目前常用处理方法存在二次污染、费用高、稳定性较差等弊端。生物炭作为经济除磷材料已被广泛研究,但缺乏其处理实际养殖尾水的基础数据。制备了4种生物炭,即杉木生物炭(WBC)、菌渣生物炭(VBC)、鳗鱼粪便生物炭(MBC)及改性杉木生物炭(SBC),并研究其对淡水养殖场尾水、淡水养殖场尾水浓缩水及海水养殖尾水中磷的去除效果。结果表明,生物炭对TP的去除效果随着投加量的增加而提高,SBC处理效果最优,VBC次之,WBC除磷能力较差,而MBC则会释放磷。SBC对3种养殖尾水中活性磷的吸附在30~60 min后达到平衡(去除率76.78%~93.07%),而对有机磷的去除率仅为14%~17%;SBC对不同形态磷的吸附过程均可用拟二级动力学模型拟合,且吸附活性磷的机制主要为配体交换和化学沉淀。该研究有望为生物炭处理实际含磷废水提供指导,促进生物炭及其改性材料从基础研究走向实际应用。

Aquaculture tailwater with excessive phosphorous can easily lead to eutrophication of receiving water body.The existing treatment methods have disadvantages such as secondary pollution,high cost,and poor stability.Biochar as a low-cost adsorbent for phosphorus removal has been extensively studied,while basic data on the treatment of actual aquaculture tailwaters using biochar are lacking.Herein,four biochars,i.e.,wood biochar(WBC),vancomycin fermentation residue biochar(VBC),eel manure biochar(MBC),and seawater-modified wood biochar(SBC),were prepared.Meanwhile,the phosphorus removal effects on three actual aquaculture tailwaters(freshwater,concentrated and marine tailwaters)were investigated.The results showed that the removal efficiency of total phosphorus by the biochars increased with the increase of dosage.Among them,SBC exhibited the best adsorption performance,followed by VBC.WBC was less capable of removing phosphorus,while MBC could not adsorb but even release phosphorus.The adsorption of phosphate in three tailwaters by SBC reached equilibrium at 30-60 min with the removal rate of 76.78%-93.07%,while the removal rate of organic phosphorus was as low as 14%-17%.The kinetic data for different forms of phosphorus could be well fitted by the pseudo-second-order.The adsorption mechanism of phosphate by SBC primarily included ligand exchange and chemical precipitation.This study is expected to provide guidance for the treatment of actual phosphorus-containing wastewater by biochars and promotes biochars and modified biochars from basic research to practical application.