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| Risk Assessment Checklist | ||||
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| Low Rick | Medium Risk | High Risk | Your Risk | |
| Solid wastes | There is no garbage disposal in the kitchen. No grease or coffee grounds are put down the drain. Only toilet water is flushed down the toilet. | There is moderate use of a garbage disposal and some solids are disposed of down the drain. | There is heavy use of a garbage disposal and many solids are disposed of down the drain. Many paper products or plastics are flushed down the toilet. | High Medium Low |
| Cleaners, solvents and other chemicals | There is careful use of household chemicals (paints, cleaning products). No solvents, fuels or other hazardous chemicals are poured down the drain. | There is occasional disposal of hazardous household chemicals in wastewater. | There is heavy use of strong cleaning products that end up in wastewater and excess chemicals are disposed of in wastewater. | High Medium Low |
| Water conservation | Only water-conserving fixtures and practices are used. Drips and leaks are fixed immediately. | Some water- conserving steps are taken ( such as using low-flow shower heads and toilets and running washing machines and dishwashers when fully loaded). | Standard high- volume bathroom fixtures are used (toilets, showers, faucets without aerators). No effort is made to conserve water. Leaks are not repaired. | High Medium Low |
| Water usage | Laundry and other major water uses are spread out over the week. | Several water-using appliances and fixtures are in use in a short period of time. | High Medium Low |
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Sewer and Wastewater Treatment Plant Inputs
What Solid Wastes Are Acceptable?
The city’s wastewater treatment system should not be used as a substitute for the trash can or a compost pile. Dispose of tissues, diapers, baby wipes, sanitary napkins, tampons, condoms, cigarette butts and other solid wastes in the household garbage and not down the toilet. Since these materials do not break down easily, they will cause the settling tanks in a municipal treatment plant to fill up faster.
A kitchen garbage disposal should be used wisely. Overuse can greatly add to the solids load in the wastewater stream and certain foods such as excess grease, fats and coffee grounds can clog pipes and slow the treatment process.
Consider composting food wastes and even some paper products as an alternative to heavy garbage disposal use. You can learn more about composting in Chapter 7 – Managing Household Trash or by calling the Washington County Cooperative Extension Service at 444-1755.
What Household Chemicals Can Go Down the Drain?
Wastewater treatment systems are not designed to neutralize the wide variety of common household chemicals. Paints, solvents, acids, drain cleaners, oils and pesticides can disrupt chemical and biological treatment processes and result in toxic effluent leaving the treatment plant.
Though generally safe when diluted, high concentrations or large volumes of water-soluble cleaners or bleach can have an impact – especially during periods of low flow into the treatment facility such as summer and late hours throughout the night. See Chapter 4 – Storage and Handling of Hazardous Household Products for more information on the proper disposal of hazardous chemicals.
Average household water usage is shown in the chart.
There are many steps you can take around your house to reduce how much water you use. Here are a few:
| Take a Tour Through the Fayetteville Wastewater Treatment Plant... | |
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| Discharge to White River | |
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Fayetteville Pollution Control Facility A.
Administration building and lab |
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Wastewater Flow and Treatment Processes
Wastewater enters the plant and passes through (1) barscreens that remove debris. Next, dome shaped units called (2) vacuators remove grease and grit from the water. Water is collected in the basin of the (3) primary influent pump station and pumped to the top of the (4) primary clarifiers. In these large sedimentation tanks solids settle out and are collected at the bottom while surface skimmers remove floating material. The flow continues to the (5) aeration basin where it mixes with activated sludge. Activated sludge is teeming with microorganisms that use remaining water pollutants as food. It is important to keep the microbes mixed and supply oxygen with mechanical aerators. If these microbes are destroyed by chemicals in the waste stream, then the waste will not be treated properly. In addition to biological nutrient removal, we can also remove phosphorus chemically using alum. When biological cleaning is complete we separate the activated sludge in (6) secondary clarifiers. The sludge settles to the bottom of the clarifiers. The water flows now to the (7) effluent sand filters that trap suspended solids in beds of fine sand. The water continues to the (8) chlorination/ post aeration basin where the water is disinfected with chlorine. Excess chlorine is removed with sulphur dioxide. Finally, the water is saturated with oxygen by mechanical aerators. Liquid oxygen can also be used to increase oxygen levels. This completes water treatment and water is ready for discharge at the (9) effluent pump station. Clean water can be discharged to the White River, pumped to Mud Creek, used for irrigation or stored in ponds for further treatment. Now it is time to deal with the pollutants removed from the wastewater. Waste sludges collected from clarifier bottoms are pumped to (10) gravity thickeners, small settling basins that concentrate the sludges. Thickened sludges and grease are pumped to (11) aerobic digesters where microorganisms continue to break down and reduce the amount of sludge. Oxygen is supplied with large air blowers. The digested sludge is then pumped to (12) sludge storage basins and finally to the (13) sludge reservoir. The digested sludge is now ready to be pumped to the sludge management site to be used as fertilizer. If sludge cannot be applied at the site, it can be dewatered for burial with (14) sludge processing equipment.
| Products that should not be poured down the drain: |
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| Insecticides Floor care products Anitfreeze Brake Fluid Motor Oil Herbicides Rat Poison Lighter Fluid Photographic Chemicals |
Furniture Polish Metal Polish with Solvent Battery Acid Gasoline and Other Fuels Paint Paint Thinner Varnishes Wood Preservative Swimming Pool Acid |
Twice in the last three years the effluent from the Fayetteville Wastewater Treatment Plant has failed its toxicity tests. This means that the plant effluent had the potential to be toxic to stream life.
The cause of the problem was determined to be Diazinon. It has been calculated that one pound of pure “diazinon”, the active ingredient in many lawn insecticides, can cause problems with plant discharges. Think how many pounds are currently stored in homes within the city limits of Fayetteville!
If you have a product to dispose of and are not sure if it is safe to pour down the drain, please call the treatment plant staff to ask. The number is 443-3292.
Certain times of the day are worse than others for the plant to receive hazardous chemicals. Certain times of the year are also worse. This is because of the nature of the inflow to the plant. When there is more flow coming into the plant, chemicals and their effects are more diluted. The lowest flow to the plant occurs during the summer months. The highest flow during the day occurs between noon and 2 p.m.
Facts About Fayetteville’s Wastewater Treatment System
The discharge from the wastewater plant contains only 5 parts per million total suspended solids, 2 parts per million ammonia and 1 part per million phosphorus.
The plant is permitted to discharge up to 6 million gallons per day to Mud Creek which flows to Clear Creek then to the Illinois River which is designated as a “scenic river” in Oklahoma. It is also permitted to discharge 6 million gallons per day to the White River which flows to Beaver Lake, the drinking water supply for much of northwest Arkansas.
About three-fourths of the waste arriving at the plant is from homes in Fayetteville. The other one-fourth is from industry, mainly food processing industries.
The sludge which is leftover from the treatment process is used for fertilizer and produces high quality hay from 600 acres of bermudagrass. The hay is then sold to local livestock producers. This allows a waste product to be converted into a useful one.
The “Paul Noland Treatment Facility” is located on the southeast side of Fayetteville at 1500 Foxhunter Road. The plant is operated by Operations Management International (OMI). Since the plant is usually out of sight and is miles down the drain from the average house in town, it is usually forgotten about. People just assume that any waste product can be sent down the drain and will be taken care of before it is released into the river.
This is not necessarily true. Several products found in the average home should not be poured down the drain because they cannot be properly treated by the wastewater plant or they may cause harm to the bacteria responsible for making the plant work.
This chapter was written by Barbara Kneen Avery, Cornell Cooperative Extension. It was adapted for Urban Home*A*Syst by Katie Teague, Washington County Cooperative Extension Service, University of Arkansas.
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