Water Resources Research Act Program

Details for Project ID 2006ND99B

Using Entrapped Cell Systems for Treating Supernatant from Anaerobic Digester of the Moorhead Wastewater Treatment Plant

Institute: North Dakota
Year Established: 2006 Start Date: 2006-03-01 End Date: 2007-02-28
Total Federal Funds: $10,800 Total Non-Federal Funds: $21,600

Principal Investigators: Khan Eakalak

Project Summary: High strength wastewater resulting from sludge treatment, such as supernatant from anaerobic digestion and centrate from sludge dewatering, is one of the major problems for municipal wastewater treatment plants (WWTPs). In most WWTPs, anaerobic digester supernatant and centrate are recycled to the biological process of the plant, which treats wastewater stream, such as activated sludge, trickling filter, and rotating biological contactor. The biological wastewater treatment processes, which normally receive low strength domestic sewage, can be upset when they are fed with the supernatant and centrate, which have very high organic concentrations. Cell entrapment, sometimes referred to as cell encapsulation, is the most popular approach for cell immobilization, which is one of the most widely used biotechnologies in food, pharmaceutical, and biomedical fields. As opposed to an alternative approach, cell adsorption, in which cells attach to surfaces, the entrapment is the trapping of cells within a three-dimensional matrix whose pores are smaller than cells. The matrix must be constructed around the cells. The materials for entrapping cells range from natural polysaccharides and proteins to purely synthetic polymers such as polyacrylamide, alginate, cellulose triacetate, and carragenan. The media, which cells are in, are permanent and reusable.The recycling of digester supernatant is a shock load that sometimes upsets the HPO-AS process and/or causes high NH4-N in the effluent. Meeting N discharge limitation is one of the difficulties that the plants have to face with currently. Removing N from the digester supernatant before returning will reduce the risk for process upset and will make it easier for the plant to meet N discharge permit.