One of the major costs associated with the operation of biological wastewater treatment is the handling and disposal of sludges generated primarily in the conversion of soluble organics as measured by BOD/COD into either carbon dioxide (aerobic) or methane (anaerobic), water and bacterial cells. Often times the sludge generated in either of these processes may be subsequently treated in a digestor to reduce the volatile suspended solids (VSS) volume for disposal. Bioaugmentation with certain microbial consortia has been shown to lower the generation of solids in both aerobic and anaerobic wastewater processes by reducing the yield coefficient (y), as well as enhancing the efficiency of digestors designed to reduce the volume of solids for disposal.
A WWTP in Southeast Georgia located on a resort island has a 3 million gallon per day flow. The WWTP was experiencing major odor problems at the head of the plant, as well as poor digestion and settling of bio-solids in the SBR’s and aerobic digesters. The odors were primarily H2S and were the source of numerous complaints from the residents living in the vicinity of the WWTP. The plant was hauling and disposing an average of 125 to 150 tons of bio-solids per month at a cost of approximately $60 per ton, which equates to $7,500 to $9,000 total average hauling/disposal charges per month.
Situated in South Donegal, Enviro Grind is a waste recycling company that has diversified into the reprocessing of organic waste streams. Enviro Grind operates an ABP Category 3 approved in-vessel composting facility and takes in feedstock including
catering industry waste, pre and post food processing waste, fish and shellfish processing waste, some sludge material and green/garden waste.
Shoal Lake is a small town of less than 1,000 people in western Manitoba. The wastewater generated by the town is treated in a series of three aerated facultative lagoons to lower key pollutant discharge parameters prior to discharge to the lake. The lagoons are in series and referred to as Cell #1, #2, and #3. Cells #1 and #2 are both 49 years old with a surface area of 5 acres and a depth of 6 feet with an approximate volume of 10 million gallons (MG). Cell #3 has been in service for 26 years and is 7 acres by 6 feet deep with an approximate volume of 14 MG. Normal inflow into the series of lagoons is approximately 0.22 million gallons per day (MGD). There is an estimated 2 feet of sludge in each lagoon. This sludge build-up reduces the working volume of the lagoons and the hydraulic retention time (HRT) of the system by about 30%.
Busan is the second largest metropolis in South Korea. With a population of 3.6 million, it is second in size only to Seoul. With rapid urban development the city of Busan was continually challenged with increasing wastewater treatment demand.
The city’s anaerobic digester was only functioning at 70% of design efficiency based on volatile suspended solids (VSS) reduction.
A city of 14,000, Kerman is located 15 miles West of Fresno, CA. As the business and commercial center for Fresno County, this city was cited as one of the fastest growing cities in central California with 150% growth since 1990. Typically, fast population growth puts a strain on local services and the town’s sewer maintenance was no exception.
The primary influent pond is in a series of seven oxidation and maturation ponds serving the municipality of Drakenstein, S. Africa. This system was designed to allow the final maturation pond to be a polishing pond for nitrification to allow effluent of suitable quality to be discharged to the river. However, due to the high level of incoming organics the initial ponds are not effective enough to allow the system to work as designed. The key to this system is to improve treatment in the initial influent
pond to a level that allows efficacy in the remaining system.
Zutphen is a medium sized activated sludge system treating an average of 6,600m3 of wastewater per day. The plant comprises two parallel trains with segregated recycle lines so that a side-by-side comparison could be conducted.