The City maintains nearly 400 miles of sewer mains and transmission lines throughout the City, allowing the sewage to make its way from the consumer to the wastewater treatment plant where it can be properly cleaned and treated.
The Wastewater Conveyance Division also maintains 57 sewer lift stations in the wastewater collection system. These lift stations are a key component in maintaining the collection system. Due to the large geographic area that Port Arthur covers, a single pipe cannot run continuously from the northern edge of Port Arthur all the way to the wastewater treatment plant. The sewage flows into a deep pit with pumps that "lifts" the sewage to a higher elevation where it can start flowing downwards again.
Years ago, when sewage was dumped into waterways, a natural process of purification began.
First, the sheer volume of clean water in the stream diluted wastes. Bacteria and other small organisms in the water consumed the sewage and other organic matter, turning it into new bacterial cells, carbon dioxide, and other products.
Today’s higher populations and greater volume of domestic and industrial wastewater require that communities give nature a helping hand, by means of a wastewater treatment plant (WWTP).
The Wastewater Treatment Division operates and maintains the City's three activated sludge treatment plants, measured in Gallons per Day (GPD). The WWTPs remove an average of 99.5% of contaminants from wastewater.
• Sabine WWTP – 300,000 GPD
• Main WWTP – 9,200,000 GPD
• Port Acres WWTP – 2,750,000 GPD
The basic function of wastewater treatment is to speed up the natural processes by which water is purified. There are two basic stages in the treatment of wastes, primary and secondary, which are outlined here.
In the primary stage, solids are allowed to settle and removed from wastewater.
The secondary stage uses biological processes to further purify wastewater.
To complete secondary treatment, effluent from the sedimentation tank is usually disinfected with chlorine before being discharged into receiving waters. Chlorine is fed into the water to kill pathogenic bacteria and reduce odor. Done properly, chlorination will kill more than 99 percent of the harmful bacteria in the effluent.
Many states now require the removal of excess chlorine before discharge to surface waters by a process called dechlorination. This protects fish and other aquatic life as the cleaned water returns back to the environment.