18 Mar 6 Steps to Treat Wastewaters- ECOFLO, Inc.
Wastewater and the release of wastewaters are a very timely topic with spills in the Mid-Atlantic region of the United States raising concerns about drinking water safety as well as that of our water resources. Wastewater Treatment Plants (WWTP), whether pricately owned or publicly owned (POTW) have rigid processes in place to filter and treat industrial and naturally ocuring wastewaters, often times with hazardous pollutants.
ECOFLO can transport your company’s wastewater via our rolling fleet of trucks including tankers and vac trucks and dispose of the waste at one of ECOFLO’s vetted and approved network of compliant and environmentally responsible WWTP’s on the East Coast.
Below is a primer for how WWTPs treat the wastewaters that it accepts:
1. Screening:
Wastewater entering the treatment plant will often contain items like wood, rocks, and debris. Unless they are removed, they could cause problems later in the treatment process. Most of these materials are sent to a landfill.
2. Pumping:
The wastewater system relies on the force of gravity to move wastewater so WWTPs are located on low ground, often near a river into which treated water can be released. If the plant is built above the ground level, the wastewater has to be pumped up to the aeration tanks (item 3). From here on, gravity takes over to move the wastewater through the treatment process.
3. Aerating:
One of the first steps that a water treatment facility can do is to just shake up the wastewater and expose it to air. This causes some of the dissolved gases to be released from the water. Wastewater enters a series of long, parallel concrete tanks. Each tank is divided into two sections. In the first section, air is pumped through the water.
As organic matter decays, it uses up oxygen. Aeration replenishes the oxygen. Bubbling oxygen through the water also keeps the organic material suspended while it forces ‘grit’ to settle out. Grit is pumped out of the tanks and can be disposed of in landfills.
4. Removing sludge:
Wastewater then enters the second section or sedimentation tanks. Here, the sludge (the organic portion of the sewage) settles out of the wastewater and is pumped out of the tanks. Some of the water is removed in a step called thickening and then the sludge is processed in large tanks called digesters.
5. Removing scum:
As sludge is settling to the bottom of the sedimentation tanks, lighter materials are floating to the surface. This ‘scum’ includes grease, oils, plastics, and soap. Slow-moving rakes skim the scum off the surface of the wastewater. Scum is thickened and pumped to the digesters along with the sludge.
6. Killing bacteria:
Finally, the wastewater flows into a ‘chlorine contact’ tank, where the chemical chlorine is added to kill bacteria, which could pose a health risk, just as is done in swimming pools. The chlorine is mostly eliminated as the bacteria are destroyed, but sometimes it must be neutralized by adding other chemicals. This protects fish and other marine organisms, which can be harmed by the smallest amounts of chlorine.
The treated water (called effluent) is then discharged to surface waters like a local river or the ocean.
