Running Head WATER QUALITY AND WASTEWATER MANAGEM Essays - Water

Running Head: WATER QUALITY AND WASTEWATER MANAGEMENT TUI UNIVERSITY Timothy N. Tarrant Module 3: BHE 314 Environmental Health and Safety Dr. Rania Sabty-Daily 14 August 2008 Abstract The purpose of this case study is to compare and contrast the secondary water treatment method to the tertiary water treatment (also known as advanced or final water treatment) method, in the context of the wastewater treatment process and to discuss the appropriate uses of reclaimed water. In addition, I will explain whether I would recommend secondary treatment or tertiary treatment for the groundwater recharge, if it were to be used for drinking purposes. Reclaimed water is wastewater that is treated. Wastewater includes domestic sewage and industrial waste. It is treated to remove harmful or unwanted items in an effort to improve the quality of the wastewater. It is accomplished for a variety of reasons and has a multitude of uses. For example, it is done to keep nature from becoming polluted, to conserve needed potable water for human consumption, power generation, irrigation, fire protection, and even for the conservation of marine life. The treatment process will reduce the amount of suspended solids, biodegradable organics (BODs), pathogenic bacteria, and nutrients. The treatment process involves three stages that can be used individually or in conjunction with one another for a cleaner water end product. The stages are: primary or physical, secondary or biological, and tertiary or chemical. During the physical treatment the removal of large floating solid materials from raw sewage occurs. This primary process is often referred to as "mechanical treatment" because it uses screens and traps, along with gravity, to remove up to 60% of solid materials. In addition, it also is able to remove up to 30% of the BOD of the wastewater. The secondary and tertiary treatment processes have both gone through primary treatment. The main difference between the two is that secondary treatment is designed for the removal of biodegradable organic matter and the removal of additional suspended solids and the tertiary treatment involves chemical disinfection. The activated sludge treatment process is the secondary process that is most often used because of its versatility and relative low cost. The tertiary treatment process removes suspended, colloidal, and dissolves any remaining constituents after secondary treatment. The tertiary treatment is able to remove more than 99% of all impurities from sewage. This produces a water quality that almost meets the standards to drink. In an article from the World Health Organization website, it was discussed that groundwater recharge might be used in the future as a potable source. The article goes on to say, " Inasmuch as recharged groundwater may be an eventual source of potable water supply, groundwater recharge with recycled municipal wastewater may often involve treatment beyond the conventional secondary wastewater treatment level. In the past, several apparently successful groundwater recharge projects were developed and operated using primary and secondary effluents in spreading basins. However, because of the increasing concerns about protozoan cysts, enteric viruses, and trace organics in drinking-water, groundwater recharge with recycled wastewater in industrialized countries now generally entails further treatment after conventional secondary treatment. For example, surface spreading operations practiced in the USA to reclaim wastewater commonly include primary and secondary wastewater treatment, tertiary granular-medium filtration and, finally, chlorine disinfection." It is with this in mind that I would choose to use the tertiary treatment process vs. secondary for groundwater recharge 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 the agricultural, industrial and municipal because it is readily available. In an effort to manage our drinking water supplies, we must turn to ideas like reclaimed water to provide a reliable source of water for non-potable uses. In 2006 the Southwest Florida Water Management District has used reclaimed water 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 using water reclamation to benefit their society. In an article called "My Clearwater/Reclaimed", it says, "The use of reclaimed water (RCW) helps us preserve high quality drinking water, by providing a reliable and economical alternative source of irrigation water. It is in coastal areas like ours that ground water supplies are most limited. The use of reclaimed water for irrigation helps us manage our drinking water supplies and costs because we postpone the day when we'll have to acquire new drinking water supplies. Drinking water is a precious, limited resource, while