b'GENERAL INFORMATION When a public sewer system is not available, a building sewer When a public sewer system is not available, a building sewer is required to is required to have an on-site have an on-site wastewater treatment system. Local and state authorities typicallywastewater treatment system. regulate on-site sewage treatment systems. There are two main types of onsiteLocal and state authorities wastewater treatment systems: typically regulate on-site sewage 1. Anaerobic - (no oxygen) treatment systems.2. Aerobic - (oxygen using)This document will discuss the anaerobic systems and how they are used in anFEATURESanaerobic treatment system. The typical anaerobic treatment system will consistOSHA Manway Access Coverof a septic tank with the effluent discharging into a sub-surface soil absorptionChemical Resistant Tank field, bed, one or more seepage pits, or a combination of these. ConstructionSYSTEM COMPONENTS Prepackaged System for Easy Specification & InstallationThe ParkUSA anaerobic treatment system includes the following standard Maintenance Notification & optional components: System; Alerts of Tank FullConcrete Containment VaultCapacity High Level Monitoring Sensors & ControlsOptional Metering Pump &Precast Concrete Controls Access covers or hatchwaysSafety hatch nets OPERATIONThe domestic sewage that discharges down the building sewer is composedof water and waste matter. There are two types of waste matter, suspended solids like coffee grounds and dissolved solids like sugar in coffee. This sewage will quickly clog all but the most porous gravel soil formations.A major function of a septic tank is to remove as many solids as possible fromthe sewage. The out flowing liquid (effluent) will finally be distributed overan adequate area of land where it can be dispersed in a soil absorption field.The absorption field is usually a series of parallel trenches, each containinga distribution pipe embedded in drain field gravel. The effluent drains out through holes in the pipe into the gravel bed, and then into the soil. The soil filters remaining minute solids and pathogens (disease-producing microorganisms). Water and dissolved substances slowly percolate outward into the soil and down toward ground water or restrictive layer. Some of the water evaporates or is used by plants.A second function of the septic tank is to treat the solids remaining in the tank with bacteria of the anaerobic species (only active in the absence of oxygen).Given enough time, these bacteria decompose the solids, and eventually make them stable. This decomposition or treatment of the sewage under anaerobic conditions is termed putrefaction or septic hence the name of the tank.A third function of the tank is to store the solids. A rock is chemically stable, whereas an orange, for example, is unstable because bacteria and fungus can decompose it until it is stable and is no longer subject to bacterial action. This process of bacterial breakdown is called digestion. There are three layers in the tank. These include sludge at the bottom (heavier solids that have settled), scum at the top (fats and greases, light solids that have risen), and in-between, relatively clear sewage that still contains sugars, detergents, and other dissolved solids.The anaerobic bacteria work in all three layers. These bacteria reduce the size and weight of the solids by turning a large part of them into liquids and gases. Thus,a pound of solids entering a tank may be only a fraction of the weight three months later. Every time raw sewage enters the tank, it forces an equal amount of treated sewage out of the tank. Septic tank tees or baffles prevent the sludge and top scum layer from exiting the tank with the treated sewage. The sewage effluent leaving the tank may still contain pathogens and are dispersed into the soil absorption drain field. Bacteria present in the soil carry out further digestion.444'