Wastewater Treatment

Wastewater first enters the collection system through plumbing and sewer lines coming from homes and businesses. These lines are connected to collection mains throughout the County, which connect with major trunk mains that flow to the treatment plant. Treatment plants do what rivers, lakes, and streams used to do before there was too much wastewater for nature to handle alone. They remove solids, reduce organic matter and pollutants, and restore oxygen to water before putting it back into natural bodies of water like streams and rivers.

  1. The treatment process begins once wastewater reaches the plant headworks from the Influent Lift Station where the trunk mains converge.
  2. The headworks consist of a mechanical screen. The mechanical screen separate coarse material such as rags, woods, and trash from the water. This protects treatment pumps and removes anything solid that could interfere with the flow.
  3. The screened wastewater flows to one of two sequencing batch reactors. The SBR is operated as a fill and draw unit process. Wastewater is added to the reactor during a fill period, mixed and aerated, then allowed to settle before the supernatant (secondary effluent) is decanted. Following the treatment of a batch of wastewater and the solids-liquid separation achieved during the settle phase. It is necessary to remove approximately the same volume of liquid that entered the reactor during the Mix Fill and React Fill phases of operation This water is called the supernatant of secondary effluent.
  4. The secondary effluent flows by gravity to a Parshall flume for flow measurement. The effluent then flows to a storage pond.
  5. Treated effluent is stored in the storage pond until it is irrigated on 11 sprayfields with a combined wetted area of 151.45 acres.
  6. The sprayfields are the networks of pipes and valves through which the effluent flows from the pumps are the storage ponds to the sprinklers.
  7. A portion of the solids is pumped to the aerobic digester to maintain an appropriate concentration of mixed liquor in the reactor.
  8. The digested sludge is pumped to a belt press where it is processed and put into a dumpster and hauled to a landfill.
  9. The reject pond can be utilized for wet weather or emergency diverting flow from the filters. Flow leaving the reject pond can be routed to the sand filters or to the head of the plant.

Click here to see the process: