Eliminating Sewer Surcharges
By: Robert D Judson, PE

Congress enacted Public Law 92-500 in the mid-seventies to provide a means to recover costs of waste treatment from industrial users. The law requires any industry that discharges wastes into a public water supply to pay their pro rata share of treatment cost. Municipal waste strengths are measured in terms of BOD (biological oxygen demand), SS (suspended solids) and FOG (fats oils and greases). Domestic values for wastes typically run 300 PPM for BOD, 200 PPM for SS and less than 1.0 PPM for FOG.

The surcharges are applied on a per pound basis by converting the concentration of wastes to lb/day by using the flow/day of wastewater which is then converted to lbs/month. We have all seen huge surcharges for waste treatment with annual billings in the $500,000 to $1,000,000 range for large facilities. The final attempt to minimize the surcharge is at the treatment plant. However, we believe there are four legs of the stool for eliminating wastewater; they are:

Flow The first component of the equation that drives your surcharge is flow and the other is the waste source itself. The flow component can be identified and managed with a succinct water conservation program. The program needs to have buy-in from operations and sanitation for it to work effectively. The sources of flows need to be identified and studied to determine how flow reductions can be achieved – remember, we can’t control what we don’t measure.

Waste Characterization This can be done by spending time on the floor talking with your operators and hourly workers. Steps include: complete flow diagrams of the waste streams including all raw materials that become waste or hit the flow; determine concentrations and volumes and convert them into flow values, BOD concentrations, suspended solids and FOG; determine what can be done to remove or minimize the waste at its source before it is diluted with other waste stream products and becomes very expensive to remove.

Recycle Identification This phase includes evaluation of the wastes to determine what can be recovered as by-products for resale. It could also include evaluation of processes to determine if equipment or process changes can be made to reduce waste resulting from additional wash-downs and change-overs or improved yields resulting from alternate process equipment.

Waste Treatment Optimization There are many types of treatment facilities including DAF, Trickling Filter, Extended Aeration, Spray Irrigation, Overland Flow, etc. The context of this brief summary does not allow time to expand on the many solutions that are available. However, each and every one has various opportunities for improvement.

Emergent has helped clients achieve state environmental awards as a result of improved waste treatment operations. The operations were a combination of flow reduction methods, waste reductions at the sources inside the plant and waste treatment operational improvements. One client was slated to build a new waste treatment facility to stay in compliance with their permit, only to find they could recover a bi-product in the waste stream that produced annual revenue in excess of $90,000 which eliminated the need to build a $1.25 Million waste treatment plant. Another facility was slated to remove their existing DAF and replace it with a new treatment system. We showed our client a method to modify their existing DAF piping and sludge wasting process in conjunction with operational changes to include hydrogen peroxide injection and avoided the $750,000 to replace their DAF. Annual surcharges of approximately $350,000/year were realized for an investment of $40,000.

Emergent has the staff and experience to assist you with your wastewater needs. Before you spend big dollars treating your wastes, see what you can do to eliminate them. It may be more profitable to treat individual waste streams through isolation than to build the big waste treatment project.