No abstract

No abstract

No abstract

The use of electrocoagulation and enhanced media filtration was evaluated for the treatment of storm water runoff from shipyards. A 15-gallon per minute (gpm) fieldscale unit was operated at Litton Avondale Industries Shipyard in New Orleans, Louisiana. The study indicated that electrocoagulation and enhanced media filtration is a cost-effective technology for treatment of shipyard storm water runoff. This technology is simple to operate and has the potential to provide a cost-effective means to treat various process wastewaters generated in shipyards. The study also indicates a need for further research on the management of solid residuals generated in the treatment process. Further research is also needed to assess the effectiveness of this technology for the treatment of other related waste streams such as ship ballast water and bilge water.

Irvine Ranch Water District's (IRWD's) Michelson Water Reclamation Plant (MWRP) produces 14 MGD of reclaimed water for unrestricted landscape irrigation. The reclaimed water distribution system includes two seasonal storage reservoirs that are considered waters of the State. Nitrogen removal at the plant and dechlorination prior to the reservoirs are therefore required. The MWRP fully nitrifies and denitrifies (N/dN) and subsequently filters and disinfects with gaseous chlorine in a 2 MG, 12 ft deep, open chlorine contact tank (CCT). The four-pass CCT is effectively operated as an extended wet well for both the reclaimed water distribution and filter backwash pumping stations. Filter effluent has an average turbidity of 0.5 NTU and less than 2 mg/L of suspended solids. CCT effluent total chlorine (Cl 2 ) residual must be maintained as high as 12 mg/L to meet the 2.2 MPN/100 mL total coliform limit required by Title 22. This Cl 2 residual multiplied by the effective contact time results in CT values that are two to three times higher than the Title 22 required 450 mg-min/L. Lower chlorine residuals typically result in higher coliform counts. Chlorine doses as high as 25 mg/L are required to maintain this Cl 2 residual. High residuals increase distribution system maintenance and chlorination/dechlorination costs. This paper presents the results of a recent study on the effect of water quality, contact time, sunlight, and CCT fluid dynamics on chlorine consumption and disinfection efficiency. The study sought to answer two questions:• Why is such a high CT value required to meet effluent coliform limits, and how can it be lowered while maintaining equal disinfection efficiency?• What causes high chlorine depletion and what can be done to reduce chlorine demand?