基于丝状真菌和嗜酸性硫杆菌配合作用的污泥生物沥浸法促进污泥脱水的研究

Bioleaching technique has been developed in recent years as a very important waste sludge treatment technology, since through bioleaching heavy metals can be removed from sludge and the dewaterability of sludge can be drastically improved. This project focuses on inverstigating the coorperation effect between filamentous fungi and Acidithiobacillus sp. during sludge bioleaching treatment. The mechanisms responsible for stimulating the growth of Acidithiobacillus sp. by the coorperation effect will be investigated. In addition, the change trends of sludge settleability and dewaterability will be investigated in bioleaching treatment based on the coorperation effect. The mechanisms responsible for enhancing sludge settleability and dewaterability under such a cooperation effect will be detailedly studied through analyzing the chemical composition change of microbial extracellular polymeric substances in sludge, and the changes of Zeta potential, structures and particle size distribution of sludge. As a result, the role of filamentous fungi in strengthening the effect of Acidithiobacillus sp. in enhancing sludge dewaterability, changing the structures of sludge particles to enhance sludge dewaterability, and stabilizing the dewaterability of sludge at the latter pahse of bioleaching will be elaborated. Results of this project will help us to understand the role of filamentous fungi in sludge bioleaching process and further enhance sludge dewaterability through bioleahcing technique based on the coorperation between filamentous fungi and Acidithiobacillus sp., which is meaningful for waste sludge treatment in the lights of bioleaching research and engineering practices.

生物沥浸技术是近年来发展起来的剩余污泥无害化、资源化处理新技术，此方法可以在去除污泥中重金属的同时大幅度提高污泥的脱水性能。本项目拟从污泥中丝状真菌与嗜酸性硫杆菌的配合作用入手，研究丝状真菌与嗜酸性硫杆菌的配合作用促进硫杆菌生长的机理。以及在此配合作用下，污泥沉降及脱水性能在生物沥浸处理过程中的变化规律，通过观测污泥中胞外多聚物EPS量及其组分变化，观测污泥的ζ电位、颗粒结构及粒径分布等的变化，详细阐明丝状真菌强化嗜酸性硫杆菌改善污泥脱水性能的效果，改变污泥颗粒的结构以提高污泥脱水性能的机制，以及稳定生物沥浸后期污泥脱水效果的机理。有助于今后采取措施强化丝状真菌在污泥生物沥浸处理中的作用，对降低污泥处理成本、污泥减量减容具有极其重要学术意义和工程实用价值。

本项目研究了丝状真菌与嗜酸性硫杆菌的配合作用促进硫杆菌生长的机理，阐明了丝状真菌强化嗜酸性硫杆菌改善污泥脱水性能的机制，建立了以污泥脱水性能改善为目标的基于丝状真菌与嗜酸性硫杆菌配合作用的污泥生物沥浸新方法。本研究从污泥中筛选出1株能改善高含固率污泥脱水性能的丝状真菌，并命名为Mucor sp. ZG-3。丝状真菌Mucor sp. ZG-3处理城市污泥过程中污泥的脱水性能改善主要受到接种方式、接种浓度和污泥含固率的影响。其最适接种方式为菌丝体接种，最适接种量为10%（v/v），最佳接种污泥含固率为4%。丝状真菌Mucor sp. ZG-3能降解污泥粘液层微生物胞外聚合物（Slime-EPS）和其中的多糖组分，从而促进污泥脱水，同时由于真菌菌丝的捕集作用，使得污泥小颗粒被菌丝捕获形成大颗粒絮体，提高污泥脱水性能。经丝状真菌降解3 d后，污泥DOM降解率高达65.2%，其中对嗜酸性硫杆菌A. ferrooxidans LX5毒性最大的L-DOM的降解率高达76.2%。降解后的污泥DOM对硫杆菌A. ferrooxidans LX5的毒性大幅降低。向污泥中先接种丝状真菌Mucor sp. ZG-3处理1 d，再接种硫杆菌A. ferrooxidans LX5处理1 d，可使污泥比阻比单独接种硫杆菌A. ferrooxidans LX5的处理低25.9%。其主要原因是丝状真菌Mucor sp. ZG-3不仅能促进污泥脱水，同时还能通过降解污泥DOM，缓解DOM对硫杆菌的毒性，为随后接入的硫杆菌提供有利的生长条件，使硫杆菌获得较高的活性，从而进一步促进污泥脱水。与耐酸性酵母菌Rhodotorula mucilaginosa R30相比，丝状真菌Mucor sp. ZG-3在分步接种生物沥浸促进污泥脱水方面效果更佳。此外，基于丝状真菌与嗜酸性硫杆菌配合作用的污泥生物沥浸新方法可大幅降低能源物质添加量，当其添加量为4 g/L时，污泥比阻降低率仍高达96.9%，使能源物质添加量降低了60%。. 因此，基于丝状真菌与嗜酸性硫杆菌配合作用的污泥生物沥浸新方法，不仅能促进污泥脱水，便于其后续处置，还能减少能源物质加入量，降低污泥处理成本，为污泥的深度脱水提供了新的技术支持。