All the water that goes down your shower and sink drain, your toilet, or the gutters and sewer grates outside, needs to be treated before it can be released back into the water system. This includes scraps from dinner, chemicals from detergents and soaps, waste from animals and humans, and all the dangerous toxins included within. Even rainwater flowing into curbside gutters is filled with chemicals, debris, and toxins.
Analysis into waterways located downstream of major urban run-off sources have found chemicals and metals like phosphorus, ammonia, nitrates and nitrites, copper, lead, and zinc. These are all toxic to humans to consume, but higher-than-recommended levels of lead, arsenic, and mercury are often discovered in homes across the U.S. According to EPA estimates, sewage treatment systems across in the U.S. release more than 850 billion gallons of untreated wastewater each year. On a worldwide scale, 80% of our wastewater is released back into the environment without any treatment at all.
Why Control is Critical
Sudden increases in phosphorus, ammonia, or other chemicals like these can over-fertilize delicate ecosystems in a process called eutrophication. This is where massive amounts of oxygen are suddenly depleted from the environment. Eutrophication is toxic to aquatic organisms, and can cause sudden death in fish, bacteria and shellfish alike. They also promote excessive flora, which reduces available oxygen, which is a major concern for ecosystems where both microorganisms and bigger organisms are heavily reliant on dissolved oxygen to survive. Decaying organic matter, and fish and human waste, can all carry pathogens. These include disease-carrying bacteria and viruses like giardia, cholera, E.coli and pneumonia. If these are allowed to travel further into the water system, they can end up being in our tap water, or in the water used to grow the food we eat.
Wastewater Treatment Facilities
Wastewater is a catchall term for all kinds of water that can no longer be used for its original purpose. This can include water that goes down your shower drain, water that’s been used to process food and manufacture products, or runoff from livestock and irrigation. Domestic or municipal wastewater is often referred to as sewage and involves all the water that it takes to wash dishes, cook food, clean clothes, water your plants, and run your bathroom. This includes businesses and restaurants and is usually sent to a treatment plant in order to remove toxins and pathogens from waste. Other times, this water is directly released into surface water.
Water that’s been used in a factory or processing plant is referred to as industrial wastewater. This water is often particularly chemical or toxin-filled, due to the materials and processes we use in order to create power and manufacture products. Sometimes factories or industries provide some form of onsite treatment, either in order to reuse the water, or to save on costs when it’s released to the sewage treatment center for further processing.
Wastewater comes in many other forms, like agriculture wastewater. This can be tailwater from an irrigation system, or water and waste from animals. Water that’s been used to water crops and flown through or past nutrient-filled soil is going to have particularly high concentrations of fertilizers, chemicals, and nutrients. This is taken into consideration when reapplying or treating the water, as reuse is particularly popular within agricultural designs.
Retaining Water (Slow your flow!)
The longer water is retained within a wastewater reservoir and its chambers, the more effective some critical treatment strategies are. For example, in initial treatment stages, a longer holding time correlates to more settling of suspended sediment. In other stages, a retention period increases the time of exposure to disinfectants and other chemical treatments. Digestion ponds depend on bacteria and other biological forces to break down organic waste in effluent. The water must spend adequate time in this step for digestion processes to be completed. The overall time that water spends within a system is referred to as HRT, or Hydraulic Retention Time.
