envi research

8/7/2019 ENVI RESEARCH

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Preliminary Treatment

The purpose of preliminary treatment is to protect the operation of the wastewatertreatment plant. This is achieved by removing from the wastewater any constituents whichcan clog or damage pumps, or interfere with subsequent treatment processes.


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S econdary Treatment

S econdary treatment is a biological treatment process that removes up to 90 percent of BODand T SS . Following primary treatment, effluent is pumped to the secondary treatment stage.It may take one of several forms; for example, either a trickling filter or a sequencing batch

reactor. The growth of microorganisms results from the consumption of organic matter in thewastewater as their food supply.


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Trickling Filter

The picture shows a trickling filter biological treatment process, which uses a bed of rocks to

facilitate contact among the aerobic bacteria, organic matter in wastewater and oxygen.


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Tertiary Treatment

Tertiary treatment is used only where it is needed to protect the receiving waters fromexcess nutrients. In tertiary treatment, the concentrations of phosphorus or nitrogen arereduced through biological or chemical processes.


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Comminutor

The drum spins counter-clockwise to this view and the silver colored teeth go through acomb-like device to shred rags, plastics, fecal matter, etc. Note the small pine cones and arubber ball.


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Rectangular Clarifier

The wastewater is put into large rectangular tanks into which air is pumped. Themicroorganisms in the wastewater use the oxygen in the air to degrade the organic wastes. Ineffect, the microorganisms use the wastes as a food source.


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S olids Treatment

Primary solids from the primary settling tank and secondary solids from the clarifier are sentto digesters for solids processing. During this process, micro-organisms use the organicmaterial present in the solids as a food source and convert it to by-products such as methanegas and water. Digestion results in a 90% reduction of pathogens and the production of a wetsoil-like material called "biosolids" that contain 95-97% water. In order to remove some of

this water, mechanical equipment such as a belt filter press or centrifuge are used to squeezewater from the biosolids, reducing its volume prior to being used in soil amendment orcomposting.


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G rit Chamber

G rit chambers are long narrow tanks that are designed to slow down the flow so that solidssuch as sand, coffee grounds, and eggshells will settle out of the water. G rit causes excessivewear and tear on pumps and other plant equipment. Its removal is particularly important incities with combined sewer systems, which carry a good deal of silt, sand, and gravel thatwash off streets or land.


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Bar S creens

Bar screens are typically at the headworks (entrance) of a wastewater treatment plant(WWTP), bar screens are used to remove large objects such as rags, plastics bottles, bricks,

solids, and toy action figures from the waste stream entering the treatment plant. Barscreens are vital to the successful operation of a plant, they reduce the damage of valves,pumps, and other appurtenances.


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Circular S edimentation Tank

In circular tanks, the flow enters either the center of the tank (center feed) or the side of thetank (side feed). If the tank is less than 30 ft (9.14 m) in diameter, the inlet pipe will enterthrough the wall and discharge into the baffle well. Then, the flow enters in a downwarddirection. If the tank is greater than about 30 ft (9.14 m), the inlet pipe will run underneaththe tank and discharge vertically in the center of the center of the baffle well. The depth of a

circular clarifier is considered to be the depth at the side of the tank, and is referred to as theside water depth (swd). This depth is used for determining tank volume and detention time.


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Rotating Biological Contactors

The RBC process involves allowing the wastewater to come in contact with a biologicalmedium in order to remove pollutants in the wastewater before discharge of the treatedwastewater to the environment, usually a body of water (river, lake or ocean). A rotating

biological contactor is a type of secondary treatment process. It consists of a series of closelyspaced, parallel discs mounted on a rotating shaft which is supported just above the surfaceof the waste water. Microorganisms grow on the surface of the discs where biologicaldegradation of the wastewater pollutants takes place.


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Activated S ludge S ystem

The activated sludge process is a wastewater treatment method in which the carbonaceous

organic matter of wastewater provides an energy source for the production of new cells for amixed population of microorganisms in an aquatic aerobic environment. The microbesconvert carbon into cell tissue and oxidized end products that include carbon dioxide andwater. In addition, a limited number of microorganisms may exist in activated sludge thatobtains energy by oxidizing ammonia nitrogen to nitrate nitrogen in the process known asnitrification.


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Operational Flow of Waste to Energy Facility

The methane gas, produced due to the natural decomposition of garbage underground, iscurrently being flared, or burned off, but soon it will become a source of energy and earnincome for the county as well.

The gas will be bought by Flint, which is an electric co-op. It will then use the gas to makeelectricity through an adjacent generating plant on county land.

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