In this age of global warming, severe droughts, and heightened environmental awareness, many companies are evaluating their production practices and establishing sustainability goals. Industry increasingly views water as a key part of their sustainability program goals. Many often consider water reduction as an easily achievable win.
Water reduction has been a key strategy for most industrial operations to meet their sustainability goals. The United Nations has established the CEO Water Mandate. This mandate establishes a global goal for the reduction in the amount of water used in the production of a product for over 200 corporations.
Water reduction makes good business sense and can be controlled by a company, reducing operational risks and costs. Water reductions can come from a variety of sources which can include changes in processes or equipment, initiation of water reuse and recycling, and retraining operations with new procedures.
Unfortunately, reducing water can create unforeseen consequences for the industrial discharger and the Publicly Owned Treatment Works (POTW). Studies have demonstrated in regions, where droughts have been significant and water conservation has occurred, there were significant negative impacts on the utility companies (Potable Water Supply and Wastewater Treatment Plant).
In 2008, the Atlanta, GA region faced a severe drought. Residents in the area significantly reduced water consumption using water conservation technologies. During this period, the local Water Department found themselves with a significant budget shortfall. The water utility brings in revenues by selling water. Local residents did such an exceptional job in conserving water that the utility did not have enough money to keep the operations going. The utility proposed a rate increase of 120% but it was not received well. Negotiations resulted in a smaller rate increase as well as a sales tax surcharge.
In addition to the reduction in potable water use, the wastewater from industry and residential customers discharging to the POTW was more concentrated. This created operational issues with the wastewater treatment systems. A re-engineering of the systems had to be made so that effluent compliance could be maintained during the drought.
Industrial water reduction also creates similar consequences. When the water use decreases so does the volume of the effluent discharge. As a result, the same amount of pollutant remains in the wastewater but concentration increases. This can affect water and wastewater treatment system performance. This is true whether the effluent is discharged to a sewer or to an on-site treatment system. Increased concentrations can lead to higher surcharges, and discharge limit exceedances.
Depending upon the pollutant, industrial wastewater pretreatment systems can be installed. The most common technologies used in wastewater pretreatment systems include: Dissolved Air Flotation (DAF), Inclined Plate Clarifiers (IPC), Oil Water Separators (OWS), Emulsion Breakers Systems (EBS), and Moving Bed Bioreactors (MBBR). Other advanced technologies also include ceramic microfiltration (CFS) and Reverse Osmosis (RO).
Pollutants such as these can be removed with the technologies listed.
- Fats, Oils, and Greases (FOG, HEM, and SGT-HEM)
- Heavy Metals
- Total Suspended Solids (TSS)
- Total Dissolved Solids (TDS)
- Nutrients (Nitrogen and Phosphorus)
Some pretreatment systems have the capability of being able to reduce pollutant concentrations so that the effluents can be used as rinse water, cooling waters, or reuse waters in other water consuming operations.
Ceramic Filtration Systems and Reverse Osmosis Systems can produce filtrates that remove TSS, TDS, and even color. These filtrates can readily be recycled in many different non-potable industrial water applications.
Fats, Oils, and Greases can be removed using Dissolved Air Flotation, Oil Water Separators, and Emulsion Breakers. These FOG and HEM materials may be able to be recycled and brought back into the production process.
Inclined Plate Clarifiers can easily remove suspended solids and are commonly used to separate chemically pretreated wastewater containing heavy metals. Depending upon the metal and concentration these may be recycled or recovered.
As water reduction increases the cost of incoming water is reduced. Unfortunately, the costs for wastewater effluent discharge or disposal often increases. Surcharges play a big part of this. Concentrates from microfiltration, reverse osmosis, and other wastewater treatment technologies need disposal off-site. Transportation fees, as well as tipping fees, can be costly.
Installing on-site water reuse/recycle system can also be affected by water reduction goals. When there is less water flowing to the water reuse/recycle system operation costs and efficiencies can be reduced.
When planning your water reduction program, look at other sustainability options in your company, and evaluate for realistic goals.
One important point is that a gallon of water that is conserved is not a gallon saved. Fresh water will still need to be reintroduced into the water sustainability program.