Project Description: In 1987, the Brazos River Authority employed KPA (formerly Roming, Parker & Associates) to begin final design on a project which would expand the capacity of the Temple-Belton Regional Sewerage System Treatment Plant from 5 million gallons per day to 10 million gallons per day. The plant serves the City of Belton and part of the City of Temple.
Specific individual studies were prepared to evaluate treatment alternatives for biological treatment, solids treatment and disposable and disinfection. The Brazos River Authority was an active participant in the studies and ten site visits were made to observe comparable equipment in operation.
As a result of the investigations, a design which included state of the art treatment was recommended. Rotating drum fine screens were included at the headworks of the plant. These screens replaced the traditional bar screens. The biological treatment process selected was a looped biological reactor which provided BOD reduction and ammonia removal. Waste solids are dewatered with belt presses and aerobically composted.
Biological treatment was designed to take place in a looped reactor. The structure consists of three endless aeration channels, arranged in a concentric manner with common intermediate walls. Raw wastewater may be introduced to any of the three channels, depending on operation conditions.
This looped reactor performs two functions; removal of organic materials and ammonia in the wastewater by biological reduction. While some bacteria are breaking down organics in the reactor, other bacteria are converting ammonia nitrogen to nitrate. This conversion, known as nitrification, takes place in two steps. Nitrosomonas bacteria convert incoming ammonia nitrogen to nitrite and Nitrobacter bacteria convert the nitrite to nitrate.
The biological reactor is followed by vacuum sludge removal final clarifiers, chlorination chambers, dechlorination equipment and cascade aeration to provide sufficient dissolved oxygen in the effluent.
During the final design of the project, additional studies were authorized to investigate alternative methods of sludge disposal. The disposal process selected was aerobic windrow composting which received an Engineering Excellence Award in 1993.
The plant was substantially complete in August 1990 and is producing an effluent with an average BOD concentration of 2 mg/l, TSS concentration of 2 mg/l and ammonia of 0.1 mg/l. Dissolved oxygen levels average more than 8 mg/l. This performance far exceeds the required quality and demonstrates a unique combination of treatment processes. Superior operation of the facility contributes to this performance.
In the words of the Brazos River Authority, “The expanded facilities have proven to be innovative and extremely efficient…”. The needs of the Brazos River Authority and the cities served by the system have been met
Construction Cost: $8,620,000 and was under budget by some $46,000.