Trickling Filter System Uses Plastic Pallets

Plastic pallets for a filtration system? We were surprised too, but it worked.

A company that builds filter systems had a unique idea. They wanted to use HDPE plastic pallets in a trickling filter system. Trickling filter systems often use a fixed bed of rocks, gravel, polyurethane foam and other material that allow wastewater to flow through and down. They are sometimes referred to as roughing filters or alternative septic systems. These systems can be used for treating residential sewage, municipal sewage systems or industrial wastewater.

To get a better idea of how this company used plastic pallets, think of a concrete structure like a large septic tank. The plastic pallets were laid on the floor of the tank and covered with poly mesh sheeting. The sheeting and the holes in the top of the pallets allowed the liquid to filter through the plastic pallets and be separated in a salt brine solution to be pumped away.

The plastic pallets and sheeting allowed an unimpeded passage for air, wastewater, biomass and solids. Together, the plastic pallets and sheeting virtually eliminating the risk of ponding or blockage.

While rocks and gravel are popular components of trickling filter systems, used tires have also been used along with plastic materials. In general, materials that can resist plugging and degradation over time are the most desirable. In this case open deck plastic pallets provided a cost-effective alternative to traditional filter material.