Pressure Sewer Systems (Design Criteria) Many different design flows can be used in pressure systems. When positive displacement grinder pump units are used, the design flow is obtained by multiplying the pump discharge by the maximum number of pumps expected to be operating simultaneously. No allowances for infiltration and inflow are required. No minimum velocity…
Costs The cost of a conventional gravity sewer system varies, based on many factors, including the depth and difficulty of excavation, the cost of labor, availability of pipe, geologic conditions, hydraulic grade line, and construction sequencing. As such, it is difficult to quantify the cost per linear foot for a particular sewer pipe size. Pressure…
Anaerobic Digestion OPERATION OF ANAEROBIC DIGESTERS The key to operating an anaerobic digester lies in balancing the acid formation and methane fermentation processes. This is accomplished by maintaining the desired temperature (95º F), ensuring mixing to promote contact between the organisms and the food as well as promoting even heating. Of high importance is FEEDING…
Rearranging a Formula Sometimes you need to substitute terms in a formula. The formula below is a common formula used to find the area of a circle. Area, sq ft = 3.14 X R X R where R is Radius However, you may be given the diameter rather than the radius. Given the diameter, you…
1. The granular filter media used to filter wastewater can become coated with a biological slime due to the _ in the wastewater. a. alkalinity b. hardness c. pH d. soluble BOD and ammonia 2. One ton chlorine tanks _. a. have fusible plugs located at valves b. must be stored in an upright position…
1. Mark the correct equation for determining the amount of chlorine required for a dosage of 10 mg/L in 500,000 gallons of flow. a. 0.05 X 7.34 X 10 = lb Cl2 b. 0.05 X 8.34 X 10 = lb Cl2 c. 0.5 X 7.34 X 10 = lb Cl2 d. 0.5 X 8.34 X…
ELECTRICITY Very few operators do electrical repairs or trouble shooting because this is a highly specialized field and unqualified operators can seriously injure themselves or damage costly equipment. For these reasons the operator must be familiar with electricity, know the hazards, and recognize his/her own limitations when working with electrical equipment. Most municipalities employ electricians…
Anaerobic Digestion Pipelines and Valves The pipe used in anaerobic digesters must be able to withstand pumping pressures and severe corrosion. Cast iron or steel is typically used. Plug valves are commonly used in sludge and scum lines. Gate valves or butterfly valves are undesirable and rarely used because grease, rags and debris can catch…
Appurtenances Drop manholes should be used when the difference in elevation between the influent and the effluent of the manhole cannot handle the drop into the barrel without creating excessive turbulence which reduces the production of H2S Back flow preventers are used to stop the accidental backflow or reverse flow of wastewater into buildings. They…
Appurtenances Appurtenances are devices that facilitate and control the flow of wastewater and allow access for maintenance activities. They include manholes, building connections, junction chambers or boxes, and terminal cleanouts, among others. Regulations for using appurtenances in sewer systems are well documented in municipal design standards and/or public facility manuals. Manholes for small sewers 24 inches…
