Project Name: Lagoon Upgrades Avoid Costly Sludge Management
Location: Town of Manning, AB (Canada)
Project Type: Municipal Wastewater Treatment
Completion Date: 2003
The Town of Manning's wastewater treatment facility consisted of a continuous discharge 3-cell aerated lagoon system. The facility was designed to handle 226 kg/day BOD5 loading at a total flow of 1026 m3/day. Upgrades were necessary to meet typical Alberta Environment (AENV) standards for aerated lagoons, namely: minimum a complete mix cell with 2 days HRT, partial mix cells with minimum 28 HRT and a settling zone with minimum 5 days HRT.
System upgrades involved replacing the previous coarse bubble aeration system with fine bubble diffusers. A new header/lateral system was also installed.
TA-22 fine bubble membrane diffusers were used to provide an oxygen rich environmental within the wastewater. The diffusers are constructed with a continuous tubular micro-porous membrane wrapped in an open spiral configuration.
Nelson Environmental Inc's (NEI) patented float/sink header assembly was used in the complete mix cell, due to the high diffuser density requirement. The float/sink header module was assembled on shore as a complete unit and was simply dragged into the pond at full water depth.
Opening the ballast control valve causes the assembly to sink to the bottom of the pond. For future diffuser maintenance or inspection the entire assembly can be raised and lowered by manipulating the ballast control valve located on shore. Because the assembly ballast is an integral part of the header system, no concrete blocks or piping remain on the pond bottom when the system is in the emerged position. Floating laterals with TA-22 diffusers suspended near the cell bottom are used in the partial mix cell. The first part of cell #1 was converted into a complete mix zone using an impermeable geo-membrane floating baffle curtain.
All system components were installed without dewatering the lagoons.
System performance data was collected. Based on monthly data obtained from January 2004 to May 2006, the average effluent BOD5/TSS values are 9/16 mg/L. This translates to roughly 93% removal efficiency for both BOD5 and TSS. This effluent quality surpasses AENV effluent quality requirements for mechanical plants (i.e. 25/25 mg/L TSS/BOD5).