Guided by federal Clean Water Act standards, extensive monitoring is done to ensure that the water and biosolids leaving the treatment facilities meet strict requirements and are safe for the environment. Wastewater received at the plant is monitored to ensure that it isn't toxic to the biological process involved in the treatment of wastewater and the water leaving the plant is tested for biochemical oxygen demand, total suspended solids, and chemical and microbiological parameters to ensure that clean water is being returned to the environment. Biosolids are also monitored to ensure that they meet the strict standards for beneficial reuse in compost and land spreading.
The primary wastewater laboratory is located at the East End Wastewater Treatment Plant, however, smaller labs are located at each wastewater treatment facility and conduct on-site process control work. Together, the wastewater labs conduct over 20,000 tests a year to ensure the environment is protected.
Industrial Pretreatment (IPT)
The Portland Water District maintains the largest industrial pretreatment program in the state. Roughly 30 industries in Westbrook and Portland participate in the program that monitors and treats the waste at the point of generation prior to discharge into the wastewater system. An effective IPT program is an important aspect of environmental protection, because wastewater plants are designed to treat domestic wastewater only. Industrial wastewater discharge may hinder the biological treatment required to properly treat domestic wastewater and may wreak havoc on the system and contaminate the environment.
The biochemical oxygen demand test, or BOD, is a common test to all wastewater treatment facilities. It is used to determine the strength of wastewater entering the facility and the removal efficiency of the treatment process. The test measures the amount of oxygen necessary to biodegrade the organic and inorganic waste contained in the wastewater. Treatment facilities are designed to remove/reduce BOD so the wastewater that’s re-introduced into the environment doesn’t negatively impact local plant and animal life.
The total suspended solids test, or TSS, is another common test to all wastewater treatment facilities. It is used to determine the amount of solid material suspended in wastewater. Treatment facilities are designed to remove/reduce TSS so that disinfection of the wastewater is more easily achieved, and so the wastewater being re-introduced into the environment is aesthetically satisfactory for such purposes as bathing.
Coliform bacteria, whether it be the fecal coliform group of bacteria or E.coli specifically, is a common test to all wastewater treatment facilities. Once BOD and TSS are removed during the wastewater treatment process, the clear, final “effluent” is disinfected with chlorine to kill disease causing microorganisms that may be present. Coliform testing is performed to ensure that these organisms have successfully been eliminated. As a final treatment step, the chlorine is removed or “neutralized” prior to the water being discharged to the environment.
The whole effluent toxicity, or WET, test replicates the total effect and actual environmental exposure of aquatic life to toxic pollutants in the effluent being discharged to the environment. It involves exposing test organisms to various concentrations of effluent for specific time periods. The tests measure mortality and sub-lethal effects such as fertilization or growth of involves exposing test organisms to various concentrations of effluent for specific time periods. The tests measure mortality and sublethal effects such as fertilization or growth of the organisms. the organisms. WET testing is a vital component of the water quality standards that are implemented through the NPDES permitting process and helps ensure that the goals of the Clean Water Act are being met.