`SYSTEMS

hold sewerage system

Aerobic treatment system

Introduction

An aerobic treatment system or ATS, is a small scale Unlike the traditional septic system, the aerobic treatment system produces a high quality secondary effluent, which can be sterilized and used for surface irrigation system. Unlike the traditional septic system, the aerobic treatment system produces a high quality secondary effluent, which can be sterilized and used for surface irrigation.

Process

• Pre-treatment stage to remove large solids and other undesirable substances from the wastewater.

• Aeration stage, where the aerobic bacteria digest the biological wastes in the wastewater

• Settling stage to allow any undigested solids to settle. This forms a sludge which must be periodically removed from the system

• Disinfecting stage, where chlorine or similar disinfectant is mixed with the water, to produce an antiseptic output.

Types of aerobic treatment systems

Fixed film systems• Fixed film systems use a porous medium which provides a

bed to support the biomass film that digests the waste material in the wastewater.

• Designs for fixed film systems vary widely, but fall into two basic categories .The first is a system where the media is moved relative to the wastewater, alternately immersing the film and exposing it to air, while the second uses a stationary media, and varies the wastewater flow so the film is alternately submerged and exposed to air.

• In both cases, the biomass must be exposed to both wastewater and air for the aerobic digestion to occur. The film itself may be made of any suitable porous material, such as formed plastic.

Continuous flow, suspended growth aerobic systems

CFSGAS systems, as the name imply, are designed to handle continuous flow, and do not provide a bed for a bacterial film, relying rather on bacteria suspended in the wastewater.

The suspension and aeration are typically provided by an air pump, which pumps air through the aeration chamber, providing a constant stirring of the wastewater in addition to the oxygenation.

Composting toiletsComposting toilets are designed to treat only toilet

waste, rather than general residential waste water, and are typically used with water-free toilets rather than the flush toilets.

These systems treat the waste as a moist solid, rather than in liquid suspension, and therefore separate liquids from solids during treatment to maintain the correct moisture level.

Within the chamber, the liquids and solids are independently broken down not only by aerobic bacteria, but also by fungi and earthworms.

Treatment times are very long, with a minimum time between removals of solid waste of a year; during treatment the volume of the solid waste is decreased by 90%, with most being converted into water vapor and carbon dioxide.

Filter Bed Systems

• These systems utilized gravel as the media through which the sewage would be filtered. Unfortunately, these older systems did not function well and did not have the ability to properly filter sewage prior to discharging an effluent to the environment.

• Modern filter bed systems now utilize filter sand as the filtration media. The sand has a filtration capability which is far superior to that of gravel.

Leaching Tile Fields

• The sewage flows from the tank to the leaching area where it drains from clay tile or perforated pipes laid in gravel trenches.

• The wastewater then enters the soil where it must be properly filtered, distributed, and absorbed so that it does not pose a contamination threat to groundwater.

• Poorly drained soils are typically saturated with water during wet weather and stay wet for long periods of time. This forcing sewerage water to rise and collect on the surface of earth thus causing foul smell.

E-T (evapo-transpiration) Fields

• Leaching systems may need to be installed at a shallower depth due to shallow bedrock or elevated groundwater conditions.

• These systems are designed with wider trenches which utilize evaporation to the air and transpiration to grasses and plants to help dispose of the wastewater. These systems are often called E-T (evapo-transpiration) systems.

• Just like conventional leaching systems, they incorporate a distribution system of perforated pipes which disperse wastewater throughout a series of gravel trenches.

• A series of distribution boxes assist in evenly spreading the flow throughout all of the trenches in the system.

Mound Systems• A mound system is an alternative to the

traditional rural septic system or leach field. • The mound system is an engineered leaching

field used in areas where septic systems are more prone to failure due to having extremely slow or extremely fast permeable soils, soil with shallow cover over porous bedrock, and soils that have high seasonal water table.

• Sand fill is used to enhance treatment of the wastewater prior to entering the natural soil at the site.

• If the soil permeability is too low, liquid is not absorbed fast enough, resulting in surface ponding of unsanitary liquids.

• If the soil permeability is too high, or is exposed fractured bedrock, the wastewater quickly penetrates down to the water table before the biofilm has time to purify the water, leading to contamination of the aquifer

Drip Distribution Systems

• Drip Distribution Systems are installed very shallow in the soil, at the surface of the ground or on top of a bed of sand, depending on the specific limiting conditions on the property.

• The systems are pressurized to ensure the even distribution of wastewater into the soil. They utilize small diameter tubing with pressure compensating emitters to apply wastewater uniformly over an infiltration surface.

• Drip distribution works on the principle of timed micro-dosing to maintain aerobic conditions in the soil.

Types Treatment of industrial wastewater

Solids removalMost solids can be removed using simple sedimentation techniques with the solids recovered as sludge.

Oils and grease removalMany oils can be recovered from open water surfaces by skimming devices.Because grease skimming involves higher viscosity hydrocarbons, skimmers must be equipped with heaters powerful enough to keep grease fluid for discharge.The wastewaters from large-scale industries such as oil refineries, petrochemical plants, chemical plants, and natural gas processing plants commonly contain gross amounts of oil and suspended solids. Those industries use a device known as an API oil-water separator which is designed to separate the oil and suspended solids from their wastewater effluents.

Removal of biodegradable organics

Biodegradable organic material of plant or animal origin is usually possible to treat using extended conventional wastewater treatment processes such as activated sludge or trickling filter. Problems can arise if the wastewater is excessively diluted with washing water or is highly concentrated such as neat blood or milk. The presence of cleaning agents, disinfectants, pesticides, or antibiotics can have detrimental impacts on treatment processes