“Birds gotta fly, Fish gotta swim, Sewage gotta smell” – or does it?

By Dave Lukas

When one thinks of sewers, wastewater treatment plants and the contents associated with them the connotation of a dark dank pipe that reeks of odors comes to mind. The treatment plant being the recipient of the sewers has to be equally offensive. For the most part this has always been true. Wastewater smells. This is the plain fact. It smells and at times it smells really bad.

Hydrogen Sulfide gas is the primary chemical produced in the sewers and smells of rotten cabbage. Hydrogen Sulfide is one of the base chemicals that other more complex odors are formed from. If the base chemical is removed then the other complex chemicals can’t form. The examples of more complex odor causing compounds could include: Mercaptans, Skatole, Indole, Putrescene, Thiols and the ever pleasant Cadaverine – each with its own odor characteristics.

The goal of economically making both sewers and treatment plants odor free, or at least greatly diminished of odors, has been to date generally unobtainable. There have been chemicals available to diminish some of the odors but the costs were extremely prohibitive. Just recently, however, a new company – Source Technologies- with a new product line came to the Northeast looking for a progressive municipality to test their products.

Their process to be tested was to take 50% hydrogen peroxide and mix it with their proprietary catalyst. Catalysts can either speed up or slow down a chemical reaction. In this case the catalyst in combination with 50 %hydrogen peroxide causes the peroxide to become “supercharged”. In this state the chemical reaction is focused on the easiest compounds to be oxidized and in our case it is hydrogen sulfide. Once the reaction occurs it is impossible for hydrogen sulfide to be regenerated once the sulfur molecule has been taken away from the hydrogen molecules. This reaction happens within 5 minutes.

Another major side benefit of the removal of hydrogen sulfide from the sewer system is that there shouldn’t be any sulfuric acid produced from the hydrogen sulfide. Sulfuric acid presently causes rapid decay to the pipes, manholes, pump stations, and all associated equipment. The infrastructure won’t be deteriorated from sulfuric acid as it does now.

The main pump station that supplies sewage to the FEV plant was the perfect location to inject and test both chemicals. The detention time to the plant is normally 10 minutes. Within minutes the odor level in the plant should have greatly diminished. Once the chemicals were applied by most accounts the odors were either greatly diminished or completely eliminated. “Smells like a trout stream “or “I smell nothing at all”or “FEV hasn’t smelled this good in 30 yrs.” was heard. This was nothing short of amazing. With such success at FEV, this process was then demo’ed at the Buttonwood Pump Station where it proved to be equally effective. Both the pump station area and the Northwest Facility became odor free. The neighbors there will equally appreciate the change to the air quality.

This process is also to be tested at Shaft #2 where it will hopefully minimize odors on the GCO force main, Plymouth Ave. , Fitzhugh St and then towards the FEV plant. Other locations throughout the County will be tested as time allows.

The overall effectiveness of this process may also help to minimize our dependence on activated carbon towers used throughout the collection system and at the plants The in- plant deodorant spray systems may also be minimized or possibly completely eliminated. The testing of this product will be ongoing through the beginning of 2008 with the obtainable goal of having the neighbors saying “Remember how FEV used to smell?

Those who have helped with this ongoing research have been Herm Thein, Manny Burgio, Steve Bland and Mary Merner, Sean Gibbons, Michelle Bowen, Gary Brown, Scott Gabel, Christy Goodrich, and Dave Lukas.