Chemical Consumption
Chemicals are an integral component of wastewater treatment, allowing MSD to treat millions of gallons a day, efficiently, while meeting regulatory requirements for effluent water quality. Figure 12 shows MSD’s chemical consumption in 2009. Chemicals also constitute a significant operating cost. For these reasons, MSD seeks to reduce chemical consumption on an ongoing basis. For example:
- In prior years, MSD completed installing ultraviolet (UV) disinfection systems at all small-volume plants. While UV disinfection consumes more energy than pure chemical disinfection, it produces a higher-quality effluent and uses less chlorine. For MSD, the cost benefit is acceptable at small facilities.
- While the Mill Creek and Little Miami treatment plants use hypochlorite for disinfection, both plants closely monitor usage on a daily basis to ensure the minimal amount needed is used for varying flow conditions and changing composition of incoming wastewater. MSD is currently reviewing alternatives for various chemicals to further reduce chemical consumption and reduce costs.
- In 2009, the Sycamore treatment plant started chemical reduction efforts related to treating phosphorus for odor control. Here, we are testing biological treatment of phosphorus, which would allow for a potential 8,000 gallon annual reduction of poly-aluminum chloride, based on 2009 usage. Testing and the transition to biological treatment will be completed by the end of the third quarter in 2010. In addition, odor issues have subsided at the treatment plant for several years; for this reason, it may be possible to discontinue the use of hypochlorite for odor control. If hypochlorite can be eliminated, the annual consumption of this chemical would be reduced by about 7,000 gallons. Currently, we are monitoring odor issues with the discontinuation of hypochlorite.