Chemical batch reactors for the treatment of milkhouse wastewater

A chemical batch reactor, or flocculator, has been developed to treat the wastewater produced as a result of cleaning and sanitizing milk pipelines and milking equipment on dairy farms. Since most dairy cleaning regimes include a phosphate based detergent and/or a phosphoric acid cleaning cycle, effluent from the milkhouse normally has a very high phosphorus concentration. Milk contributes suspended solids and fats to the wastewater. In the flocculator, calcium hydroxide, Ca(OH)(2) (agricultural grade lime) is applied to precipitate phosphorus and suspended solids from the wastewater and to cause saponification of the oil and grease. The resultant sludge (representing approximately 10 % of the original volume of wastewater) is stored and spread with the manure. This paper describes two systems which were installed in Southwestern Quebec, Canada. Average total phosphorus (TP) removal efficiencies were 95% and 99% respectively. Total suspended solids (TSS) were reduced by 86% and 90% respectively. Other prototype reactors have been installed on working dairy farms in Eastern Canada and New York State (these have been monitored to various degrees).