Evaluation of Tertiary Treatment Systems for Wastewater Reclamation and Reuse

Both bacterial pathogens and viruses are removed in varying degrees by tertiary or advanced wastewater treatment. Principal treatment processes and operations for producing reclaimed water that has an extremely low probability of virus or bacterial contamination normally include chemical coagulation followed by flocculation, sedimentation, filtration, and disinfection. Alternatively, direct filtration with lower chemical doses and without sedimentation is often used. However, optimization of the chemical coagulation and filtration of secondary effluent has been difficult to achieve in practice and has hampered the establishment of alternative and more cost-effective wastewater reclamation methods. In this paper, special reference is made to the recently completed study in Castroville, California, the “Monterey Wastewater Reclamation Study for Agriculture”, where pertinent data are used to assess design and operational variables in an attempt to optimize the performance criteria of the two tertiary treatment trains.