Evaluation of high-rate clarification for wet-weather-only treatment facilities.
High-rate clarification (HRC) processes are well suited for enhanced primary treatment of wet-weather flows in combined sewer systems. Suspended solids removal in excess of 75% of influent concentrations can be achieved consistently. Chemical oxygen demand and five-day biochemical oxygen demand removal are better than 60%. However, although optimal treatment could be achieved in a matter of minutes when the units were started full, a delay of up to one-half hour was observed when the units were started empty. Operational strategies that minimize this effect need to be developed in full-scale tests before HRC processes can be implemented with confidence in wet-weather-only facilities.
Jolis
Domènec
D
Water Pollution Control Division, San Francisco Public Utilities Commission, California, USA. djolis@sfwater.org
Ahmad
Meei-Lih
ML
D005374:Filtration; D005427:Flocculation; D011891:Rain; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements; D014873:Water Pollutants / Q000302:isolation & purification*
D012722:Sewage; D014873:Water Pollutants