Cedar City Regional Wastewater Treatment Facility - Executive Summary |
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CEDAR CITY REGIONAL WASTEWATER TREATMENT FACILITY The primary reasons for the need of this Treatment Facility are to remove risks to public health (prevent disease), to avoid foul odors and objectionable sights, both on and off the site of the treatment facility, and to prevent pollution of the receiving groundwater at the land application site. The Cedar City Regional Wastewater Treatment Facility (CCRWWTF) has been designed to provide an environmentally sound means for disposal of sanitary wastewater generated by Cedar City, Enoch, and the surrounding county area. The plant is designed to treat an average daily flow of 4.4 million gallons per day with instantaneous hydraulic peaks of 11 mgd. The CCRWWTF operates as a single-stage trickling filter treatment plant. The treatment process consists of screening, grit removal, primary clarification, trickling filtration, secondary clarification, chlorination, and land application of the effluent. Solids are handled by anaerobic digestion and air-drying. After water has been delivered to the homes, industries and commercial establishments of a City, it is used for a multitude of purposes and is eventually wasted to a sewer system. This wastewater contains an enormous variety of waste products of human, animal, vegetable, and mineral origin. Some of the waste products will be dissolved in the water and some will be suspended. There are three different types of suspended sewage solids - those that settle, those that float, and those that are so small that they neither settle nor float, but remain suspended in the water. It is the last of these, sometimes called "colloidal solids," which make settled sewage look cloudy. Normally, sewage contains in excess of 99.9 percent water and less than 0.1 percent solids. It is far more difficult to remove the solids than it was to add them in the beginning. It is this difficult job of removal of solids, which is one of the primary purposes of this sewage treatment plant. The wast ewater enters the plant from the sewer collection system where it is subjected to the "pretreatment" processes of mechanical bar screening and grit removal. The flow is then pumped into two primary clarifiers where the heavier settable solids are removed. After this "primary treatment", the flow is pumped to the two 100-foot diameter trickling filters. The trickling filters accomplish biological degradation in the secondary treatment process. The flow from the trickling filter is collected and either recycled through the plant again or sent to the two final clarifiers. In the final clarifiers, the trickling filter sloughing and other solids are removed and recycled through the plant again. After the final clarifiers, the flow goes to the chlorine contact basin. The chlorine contact basin provides disinfecting with chlorine to destroy potential pathogenic organisms. The final effluent water is pumped to a land application site where it is used to grow a variety of feed grasses. The so lids removed in the primary clarifiers are pumped to the anaerobic digesters. In the digesters, the organic matter is decomposed via anaerobic bacteria. After digestion the sludge is placed in sludge beds for solar/air drying. Once the sludge is dried it is used as a fertilizer for the growing of animal grasses. |