If freezing is the only method used to dewater wastewater sludges, then storage is required during warm periods. A more cost-effective alternative is to combine winter freezing with polymer-assisted summer dewatering on the same bed. In a typical case, winter sludge application might start in November and continue in layers until about 3 ft (1 m) of frozen material has accumulated. In most locations, this will thaw and drain by early summer. Polymer-assisted dewatering can then continue on the same beds during the summer and early fall. Sludge storage in deep trenches during the warm months is better suited for water treatment operations where putrefaction and odors are not a problem.
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