How Is Waste Water Cleaned?

Industrial waste water treatment must follow EPA guidelines

Waste water comes from homes, businesses and industry. Most of it is cleaned in a waste water treatment plant or facility in or near towns and cities. In many rural areas, homes and businesses have septic systems that are individual, small version waste water treatment systems. Industry has another set of waste water treatment protocols they must abide by to meet EPA standards.

Preliminary Teatment

Waste water leaves a building through a series of pipes that connect to a treatment plant. Then, it passes through a screen, removing solids. The solids are moved on a conveyor belt to a dumpster while the dirty water continues to the next processing step.

Waste water moves into a grit chamber where sediment such as sand, gravel and dirt sink to the bottom. There, a sump pump extracts it. Oily sediment is pumped out and incinerated.

Secondary Treatment

Pre-treated water moves to another tank where bacteria or bugs such as protozoa are introduced to remove pollutants. Oxygen is pumped into the water to improve the bacteria's performance.

When finished, bugs sink to the bottom and are pumped out. The water then flows through the chlorine channel where the water is further purified. The chemical So-2 is added to remove the chlorine from the water before releasing it back into the environment.

Solid Waste Disposal

Most solid waste from the pre-treatment process will be taken to a landfill by dump trucks. Sludge is channeled into a huge centrifuge for a de-watering process. Once the water is removed, it is incinerated at extremely high temperatures. The resulting smoke is water-sprayed to reduce the release of harmful pollutants into the environment. The ash that remains is used as an ingredient in making brick and concrete.

Septic Systems

Septic system tanks are often buried underground and must be maintained at the expense of the owner. These systems work similarly to the treatment plants but are self-contained units. Waste water is piped to the septic tank where the sludge drifts to the bottom and oil and grease float on top. The remaining water is filtered through a series of pipes and out into the soil. Regular pumping is a necessary part of septic-system maintenance.

Industrial Waste Water Treatment

Industrial waste water treatment is a complex system that requires individualized treatment processes to eliminate specific pollutants related to the particular industry. Every industrial plant needs their separate waste water treatment facility. Each must follow federal EPA guidelines to remove those pollutants. Studying the practices of each industry, defining what pollutants are used and then writing guidelines and regulations for the industry to follow help to develop these regulations and guidelines.

References

• EPA: Water Science Guide
• Metrocouncil: Environment