The primary purpose of waste water systems is to ensure that waste from homes and businesses is disposed of in a safe and effective manner. Waste water systems ensure the health of people and the environment by channeling potentially harmful and unhygienic waste products to the proper treatment plants. At these plants, the wastewater can be treated for any contaminants that may be present.
To understand what goes in when waste water is treated, it is important to first know where the process begins. Waste cannot be properly gathered to a treatment location without functional waste water systems that act as an outlet for waste from homes and businesses, and an inlet of waste to treatment centres.
Once waste water goes down the drain, into the sewer system and supplied to treatment facilities, it first undergoes a preliminary treatment process. The overall treatment of waste water includes a combination of physical, biological and chemical processes to remove organic matter, solid debris, and chemical waste.
At the initial stage, large solids and other type of debris are first filtered out of the wastewater. Different types of waste water systems are capable of handling varied types of waste. Those with larger piping may be capable of carrying larger materials, while smaller systems tend to be more selective. After filtering out solid waste, the waste water is channeled for primary treatment.
Primary treatment processes
At this stage, the waste water is allowed to settle for a period of time. Organic and inorganic particles that passed through the preliminary stage will settle at the bottom of the reservoir, while particles that float will be removed via a process called skimming.
Primary treatment is effective a removing 50-70% of biochemical waste, 70% of suspended solids, and up to 65% of oil and grease contaminants from waste water systems.
Secondary treatment processes
During secondary treatment, more specific procedures are directed at the waste water to remove suspended solids, dissolved biodegradable matter, and other organic matter in colloidal form. To achieve accurate results, the treatment is carried out using aerobic treatment processes.
These processes involve the use of oxygen and oxygen-dependent microorganisms to convert organic waste mater into other less harmful components. For example, human waste can be digested to produce water, carbon dioxide (which are less harmful than the original human waste).
In most cases, the treatment of the water contained in waste water systems stops at the tertiary stage. However, when more specific results are desired from the treated water, the water can be channeled to undergo tertiary treatment.
This step involves specific individual processes that are aimed at removing components such as heavy metals, nitrogen or phosphorus.