Greening Wastewater Treatment
Most see wastewater treatment as a necessary evil to keep watercourses clean and safeguard human health. While cleaning water for reuse is green indeed, the treatment process is not. Processing wastewater requires large amounts of energy, toxic chemicals, and produces waste solids for disposal. Recently some have recognized hidden environmental benefits for these processing “evils”.
Most see wastewater treatment as a necessary evil to keep watercourses clean and safeguard human health. While cleaning water for reuse is green indeed, the treatment process is not. Processing wastewater requires large amounts of energy, toxic chemicals, and produces waste solids for disposal.
Recently some have recognized hidden environmental benefits for these processing “evils”. One of these twists is taking place in Delhi Township, Michigan, where modifications to the wastewater treatment plant are incorporating “green” systems. HRC has completed the design and begun construction of this first of-a-kind system that may revolutionize wastewater solids (residuals) treatment.
This project involves changing Delhi's current residuals treatment practice to a two stage digestion process. The new system, which takes place in closed tanks without oxygen, incorporates a thermophilic (hotter) stage and a mesophilic (warmer) stage which produces Class A biosolids; that is, solids that are suitable for direct application to farm fields and gardens without further treatment. Thus, the soil conditioning and nutrient content of these solids might be beneficially used.
In partnership with HESCO, who will provide the digestion process, even more “greening” will be achieved. Methane gas produced by the process will be used to power microturbines and produce electricity for use at the Plant. The exhaust heat from the turbines will in turn be used to heat the digesters; closing the energy loop on wastewater residuals treatment. This system is known as “Combined Heat and Power” and Delhi's is the first in Michigan. Another unusual aspect of this project is performance specifications were prepared for the entire system instead of its individual components because of the goal to produce Class A biosolids.
The complex piping was designed using 3-D software to minimize interferences and to provide better images of the system. These improvements are being constructed by Irish Construction, who was excited to be able to participate in this “green” initiative. Encouragement for the project came from Delhi Township officials including Supervisor Stuart Goodrich, Treasurer Harry Ammon, Clerk Evan Hope and Trustees John Hayhoe, Jerry Ketchum, Paul Krepps, and Roy Sweet. Also, Township Manager John Elsinga and Director of Public Services Sandra Diorka have had active roles in implementing this project.
So what does this have to do with water?
The answer is anything that can help to operate wastewater systems in an environmentally-friendly manner, and anything that can make byproducts from the treatment process useful, and anything that can help with energy reduction is worth a closer look. In this case, the technology that is now available, in combination with a far-seeing Township, is helping to create a “greener” wastewater treatment plant.