OCR Text |
Show Status No jurisdiction in the state of Utah currently requires recycling of vehicle wash water. Existing regulations focus on control of discharges into sewer systems or storm water systems. In some cases, industrial pretreatment programs monitor the discharge from vehicle wash facilities, although industrial discharge permits have not been issued. If wash facilities do not have access to sewers, holding tanks are required for wastewater. Proper disposal of solids from any treatment process is also required. Potential Water Savings Reported water usage rates for vehicle wash facilities vary. A summary of general vehicle wash facilities and the water use associated with each is given in Table 3. All wastewater treatment facilities obtain data on the commercial and industrial dischargers in their service area to prevent toxic discharges to their facility. The three largest wastewater treatment facilities in the state were contacted to inquire how many vehicle wash facilities were located within their service area. The results of this survey are presented in Table 4. This data were projected to the entire state to determine that approximately 420 vehicle washes are currently operating within the state. Data provided by the Utah Car Wash Association indicate a vehicle wash will service 200 to 400 vehicles per day. Therefore, it is estimated that a maximum of 5.0 million gallons per day ( mgd) [ 15 acre ft/ day] of water are being used within the state to wash vehicles at commercial wash facilities. The simplest and most cost- effective system for recycling water in vehicle wash facilities involves segregating water from final rinsing and rerouting it back to the initial stages of the washing process. Reusing rinse water reduces the volume of wastewater discharged and associated sewer charges. It is important to note that reducing water without proportionately reducing process contaminants might increase wastewater contaminant concentrations, possibly resulting in discharges that exceed concentration- based limits. Contaminants in vehicle wash water include grit, oil and grease, metal and total dissolved solids. The simplest treatment systems involve gravity sedimentation and pumping clarified rinse water back to the head end of the facility. More complex treatment systems include oil/ water separation and gravity and pressure filtration. It is difficult to obtain actual operating data on removal of contaminants, particularly dissolved solids. In addition, minimal information is available on long- term reliability and operating problems, except from equipment vendors. Vendors of vehicle wash equipment claim that water usage is cut by at least 67 percent when recycle equipment is in place and technologies exist that claim to clean a vehicle with less than five gallons of fresh water. Costs of equipment range from $ 5,000 to $ 6,000 per installation. More complex systems cost between $ 10,000 and $ 15,000, and some have reportedly cost as much as $ 50,000 - 70,000. These costs do not include installation. Two types of recycle technologies are currently being used in Utah. The clarification system, being used only with friction type wash systems, can recycle approximately 50 percent of the water used. The closed loop system could be used for either type of wash system and apaproaches 90 percent recycle of water. Vehicle was sprocesses consist of two steps. In the first step, approximately 60 percent of the total volume of water isused. The rest is unsed in the second step. The wash step does not require the high water quality that the rinse step does. The clarification recycle system takes advantage of this and recycles the effluent from the rinse step into the wash step. A clarification treatment system is all that is required for the recycle water before it can be reused in this system. Clarification functions by allowing the water to set in a quiescent zone ( a series of tanks) 61 |