Billions of dollars in federal stimulus funds have been allocated toward upgrading and constructing municipal wastewater treatment plants (WWTP’s).
Ventilation is required in many plant areas because of the gaseous contaminants, including poisonous hydrogen sulfide, and fumes from chemicals used in the wastewater treatment. Some plant areas are rated as Class I, Division 2 hazardous locations.
The best opportunities for Wing are in those WWTP’s that use digester gas to fuel boilers. Opportunities include IFB and VIFB coils, FAS for combustion air preheat, SAS make-up air units, and unit heaters. A recent project involved sixteen special indoor SAS units. These units were furnished with type 304 stainless steel cabinets and linings, epoxy-coated aluminum fan wheels, and pneumatic actuators. In lieu of the standard IFB coils, VIFB coils were provided with stainless steel casings along with baked epoxy coating on the tubes and fins.
Wastewater treatment plants use a combination of physical, chemical and biological processes to remove contaminants from wastewater. These contaminants include organic matter, solids, nutrients, disease-causing organisms and other pollutants. The plant’s objective is to produce a wastewater stream and solid waste sludge suitable for discharge or reuse back into the environment.
The first step, pretreatment, involves screening out, grinding up or separating debris from the wastewater stream. Primary treatment is the second step and separates suspended solids and grease from wastewater. Secondary treatment removes dissolved and suspended biological matter. Microorganisms that absorb the organic matter as their food supply are added to the wastewater. The digestion process reduces the volume and odors of the sludge, while creating significant volumes of digester gas containing 65 to70% methane. Caustic chemicals can be added to sludge or it may be heat-treated to kill disease-causing organisms. The combination of methane gas and caustic chemicals make it important to flush portions of the plant with fresh air and that is where LJ Wing can help with rugged, stainless steel products as described above.