Evaluation of four different tertiary filtration plants for turbidity control

Abstract

The County Sanitation Districts of Los Angeles County operate 10 water reclamation plants (WRPs) for wastewater reclamation and reuse. To comply with State of California's stringent wastewater reclamation criteria, tertiary filtration systems are required at seven of these WRPs. Four types of filters, including mono‐medium gravity (activated carbon or anthracite coal), dual‐media gravity, and dual‐media pressure filters, are used. A study has been conducted to evaluate and to compare the filters' performance. The study started with evaluating turbidity and suspended solids (SS) removal by using plant operational data. Ratios of SS to turbidity were determined and found comparable among the plants. Although all filters provide good turbidity control, removal efficiencies are different among the filtration systems. Some plausible explanations for the apparent differences in removal are provided. Particle size distribution (PSD) measurements were made on samples from various locations at the WRPs to provide insights into particle removal. Typical particle size and volume distributions in the wastewater streams were established. Although turbidity and PSD could not be well correlated, particle removals by the four filtration systems were determined for better understanding of their removal mechanisms.

Deep bed filtration of anaerobic cattle manure effluents with natural zeolite

“…Other criterion consider that quantities over 5% of output volume would be excessive, but this criterion only may inform to the designer or operator whether his filter is within the accepted range. Many experimental plants usually need quantities about 12% backwash water, operating in the best selection conditions for satisfying filtrate quality criterion (Svarousky, 1981;Fair et al, 1987;Kuo et al, 1994).…”

“…ammonia compounds, orthophosphate and turbidity reported (Hill et al, 1977;Metcalf and Eddy, 1991;Kuo et al, 1994). During the filtration process, the head losses and the removal efficiency change with the time because of the retention of suspended particles in the filtering bed.…”

“…The use of the filtration process either, as secondary or tertiary treatment, has been progressively increased in the last years (Darby et al, 1991;Kuo et al, 1994) because of its high efficiency, simple operation and low cost. Initially, the filtration process design for wastewater treatment was similar to that used for drinking water treatment but this process failed due to the high concentration of suspended solids.…”