E. coli, one of the most common pathogens found in domestic wastewater, can cause gastroenteritis. This bacteria, which often lives in the digestive system, are one of many pathogens that can contaminate drinking and surface water. However, most pathogens are difficult to measure directly. Instead, a pathogen indicator can help detect fecal contamination and determine the potential for illness. E. coli can serve as a pathogen indicator in drinking water and treated wastewater to measure the effectiveness of disinfection treatments.
The chlorination process in wastewater treatment is one of the most common ways to disinfect wastewater and eliminate pathogens such as E. coli. When added to wastewater, chlorine destroys a target organism by oxidizing its cellular material. Used as chlorine gas, hypochlorite solutions or in other solid or liquid compound forms, chlorine has a long history as an effective wastewater disinfectant. Some key benefits of the chlorination process in wastewater treatment include:
Below, we give an overview of the chlorination process in wastewater and explain how municipalities can improve the performance of chlorine disinfection systems by partnering with a team of wastewater engineers.
There are several factors that affect the chlorination process in wastewater treatment, including:
The chlorination process in wastewater treatment uses chlorine in either liquid or gas form. Although chlorine dosage varies based on wastewater characteristics, it generally falls in the range of 5-20 milligrams per liter (mg/L). As chlorine solution mixes with wastewater effluent, it initiates a reaction with pathogens and destroys them.
However, post disinfection, the residual chlorine in the effluent can persist for several hours. Because chlorinated wastewater released into the environment can be detrimental to aquatic life, the wastewater must undergo dechlorination. This process removes free and combined chlorine residuals from the treated wastewater. It uses dechlorination chemicals such as sodium bisulfite, sulfur dioxide, activated carbon and sodium metabisulphite. Post-dechlorination, the total chlorine residual in wastewater is reduced to a level that is no longer toxic to aquatic life.
Chlorination and the dechlorination systems are complex to design and operate. Wastewater engineering experts can help plant owners and communities address these challenges.
Chlorine gas is extremely hazardous. Because this gas causes respiratory, eye and skin irritation, the chlorination process in wastewater treatment requires significant safety measures. Chlorination systems also have complex operations and maintenance requirements.
To overcome the challenges of handling chlorine gas, many wastewater treatment plants are switching to a sodium chlorine solution. This liquid is much safer than chlorine gas. Design innovations can also improve chlorine disinfection systems' effectiveness. Some modifications that can improve the chlorination process in wastewater treatment include:
The dedicated team of wastewater engineers at Fehr Graham helps communities update their wastewater infrastructure and modernize the chlorination process in wastewater treatments. We have improved chlorination systems by:
Our solutions minimize the effect wastewater has on surrounding bodies of water. We help municipalities find funds to bring wastewater treatment plant upgrades, including chlorination and dechlorination, within financial reach.