Water Treatment Facility – Filter Press Case Study
A small Northern California town has its own private drinking arsenic drinking water treatment facility. The system was designed with a bag type of sludge gravity dewatering system. It proved to be inadequate because it is too time consuming for drainage [with polymer] and too labor intense. Trucking the 1% solids off proved to be too expensive.
A Hengda recessed chamber filter press was proposed after a pilot dewatering project was completed. The process uses ferric chloride and chlorine to remove the arsenic. This produces an extremely fine sludge that will impede the filter press filtration process without sludge conditioning. Perlite and polymer are mixed in with the sludge after polymer thickening. This is called body feeding. The perlite is inert and not carcinogenic [like DE].
The press is raised to allow a small 10 yd roll off under the press. The cakes are between 30-40% solids. Disposal costs to the landfill are minimal compared to the generated 1% solids generated.