The most common method of biosolids disposal has been burial in a landfill. Some of our biosolids are disposed of in this method, but we also use our biosolids in another way, land application. This methods recycles the organic matter into the soil. It improves water retention, reduces acidity, adds bulk to thin soil and helps with erosion. Biosolids with enough nutrients in them can be used to improve the yields of farm lands, while mixing biosolids with leaves, shredded paper or wood chips in a composting operation create a product that can be used on lawns, in parks and on golf courses.
In many areas, biosolids are marketed to farmers as fertilizer. Federal regulation (40 CFR Pert 503) defines minimum requirements for such land application practices, including contaminant limits, field management practices, treatment requirements, monitoring, record keeping, and reporting requirements. Properly treated and applied biosolids are a good source of organic matter for improving soil structure and help supply nitrogen, phosphorus, and micro-nutrients that are required by plants. Biosolids have also been used successfully for many years as a soil conditioner and fertilizer, and for restoring and re-vegetating areas with poor soils due to construction activities, strip mining or other practices. Under this biosolids management approach, treated solids in semi-liquid or dewatered form.
At the end of our digestion process there are leftover solids that did not get broken down and need to be removed from the system and disposed of. We remove approximately 130,000 gallons of sludge each day.
30 wet tons of a 26% solid, known as “cake” are produced each day. These cake solids are conveyed out to four semi-trailers. Weather and season permitting, they are hauled to farm fields, where they are applied and incorporated into the soil. If not land applied, they are hauled to a landfill.
We run these solids through centrifuges to dewater them. A centrifuge is a long drum that spins at 2600 RPM. The solids enter on one end and using the centrifugal forces, the solids are pulled to the outside of the drum and the water is left to drain out of the center on the opposite end. The water, also known as centrate, is returned back into the liquid stream of the treatment plant.