ENTTUI UNIVERSITYTimothy N. Tarrant Module 3:BHE 314Environmental Health and Safety Dr. Rania Sabty-Daily14 August 2008 AbstractThe purpose of this case study is to compare and contrast thesecondary water treatment method to the tertiary water treatment (alsoknown as advanced or final water treatment) method, in the context of thewastewater treatment process and to discuss the appropriate uses ofreclaimed water. In addition, I will explain whether I would recommendsecondary treatment or tertiary treatment for the groundwater recharge, ifit were to be used for drinking purposes.
Reclaimed water is wastewater that is treated. Wastewater includesdomestic sewage and industrial waste. It is treated to remove harmful orunwanted items in an effort to improve the quality of the wastewater. Itis accomplished for a variety of reasons and has a multitude of uses. Forexample, it is done to keep nature from becoming polluted, to conserveneeded potable water for human consumption, power generation, irrigation,fire protection, and even for the conservation of marine life.
Thetreatment process will reduce the amount of suspended solids, biodegradableorganics (BODs), pathogenic bacteria, and nutrients. The treatment process involves three stages that can be usedindividually or in conjunction with one another for a cleaner water endproduct. The stages are: primary or physical, secondary or biological,and tertiary or chemical. During the physical treatment the removal oflarge floating solid materials from raw sewage occurs. This primaryprocess is often referred to as “mechanical treatment” because it usesscreens and traps, along with gravity, to remove up to 60% of solidmaterials. In addition, it also is able to remove up to 30% of the BOD ofthe wastewater.
The secondary and tertiary treatment processes have both gone throughprimary treatment. The main difference between the two is that secondarytreatment is designed for the removal of biodegradable organic matter andthe removal of additional suspended solids and the tertiary treatmentinvolves chemical disinfection. The activated sludge treatment process isthe secondary process that is most often used because of its versatilityand relative low cost. The tertiary treatment process removes suspended,colloidal, and dissolves any remaining constituents after secondarytreatment.
The tertiary treatment is able to remove more than 99% of allimpurities from sewage. This produces a water quality that almost meetsthe standards to drink. In an article from the World Health Organizationwebsite, it was discussed that groundwater recharge might be used in thefuture as a potable source. The article goes on to say, ” Inasmuch asrecharged groundwater may be an eventual source of potable water supply,groundwater recharge with recycled municipal wastewater may often involvetreatment beyond the conventional secondary wastewater treatment level. Inthe past, several apparently successfulgroundwater recharge projects were developed and operated using primary andsecondary effluents in spreading basins. However, because of the increasingconcerns about protozoan cysts, enteric viruses, and trace organics indrinking-water, groundwater recharge with recycled wastewater inindustrialized countries now generally entails further treatment afterconventional secondary treatment.
For example, surface spreading operationspracticed in the USA to reclaim wastewater commonly include primary andsecondary wastewater treatment, tertiary granular-medium filtration and,finally, chlorine disinfection. ” It is with this in mind that I wouldchoose to use the tertiary treatment process vs. secondary for groundwaterrecharge if it were to be used by the public for drinking. Drinking water is a precious commodity with limited resource. Reclaimed water is being viewed as a valuable resource for theagricultural, industrial and municipal because it is readily available.
Inan effort to manage our drinking water supplies, we must turn to ideas likereclaimed water to provide a reliable source of water for non-potable uses. In 2006 the Southwest Florida Water Management District has used reclaimedwater to power six local power plants, irrigate 9,000 acres of crops,irrigate 83,000 residential areas, and irrigate over 160 area golf courses. (SW Florida, 2008) Clearwater Florida is an excellent example of usingwater reclamation to benefit their society. In an article called “MyClearwater/Reclaimed”, it says, “The use of reclaimed water (RCW) helps uspreserve high quality drinking water, by providing a reliable andeconomical alternative source of irrigation water. It is in coastal areaslike ours that ground water supplies are most limited. The use ofreclaimed water for irrigation helps us manage our drinking water suppliesand costs because we postpone the day when we’ll have to acquire newdrinking water supplies.
Drinking water is a precious, limited resource,while reclaimed water is readily available. ” (Clearwater, 2006) As anation, we have a responsibility to ensure the continued preservation ofour environment and its resources. Treating and reclaiming water is oneway that we can accomplish this. ReferencesEnvironmental Services Department, City of San Jose. South Bay Water Recycling: Treatment Process.
Retrieved on August 11, 2008 from http://www. sanjoseca. gov/sbwr/treatmentprocess. htmMy Clearwater/Reclaimed (2006). Public Utilities: Reclaimed Water.
Retrieved August 11, 2008 from http://www. clearwater- fl. com/gov/depts/pwa/public_utils/divisions/reclaimed/index. aspSouthwest Florida Water Management (2008) Water Conservation: Reclaimed Water.
Retrieved August 11, 2008 from http://www. swfwmd. state. fl. us/conservation/reclaimed/World Health Organization (ND).
Groundwater recharge with recycled municipal wastewater: health and regulatory considerations. Retrieved August 11, 2008 from http://www.who.int/water_sanitation_health/wastewater/wsh0308chap6.pdf
