Evaluation of Treatment Processes

ORO LOMA SANITARY DISTRICT -WWTP Capacity Evaluation
WBA completed a capacity evaluation on the existing treatment unit and equipment sizes, together with actual plant operating data, to assess the performance of the existing treatment units under then-current flows and loadings. Those results were then used to predict the performance of the existing facilities under future flows and loadings. Weak links in the liquid and solids treatment processes were identified. Finally, estimates of the capacity of the existing facilities under typical dry weather and wet weather flow and loading conditions were made.
The evaluation concluded that the capacity of the existing wastewater treatment plant was less than the design capacity of the original design and the secondary clarifiers were the limiting treatment process. The shallow depth and square shape of the secondary clarifiers limited their ability to remove total suspended solids (TSS) from the mixed liquor to the 30 mg/L requirement applicable to the Oro Loma effluent.

SELMA KINGSBURG FOWLER COUNTY SANITATION DISTRICT – Sludge Dewatering Centrifuge System
WBA conducted a “Sludge Dewatering Study” for SKF in 2000 to estimate the onsite sludge drying bed dewatering capacity and to evaluate a supplemental mechanical dewatering system to handle the sludge production in the winter months when the onsite sludge drying beds are not operational. The Study concluded that a supplemental mechanical dewatering system is a viable and cost effective mean for the District to effectively manage the sludge production during the winter months.

Based on one of the recommendations as adopted by the District, WBA developed a onsite pilot study program and coordinated with two sludge dewatering equipment manufacturers, one for a belt press system and one for a centrifuge system, to perform onsite sludge dewatering pilot studies. Based on the results of the pilot studies,

WBA prepared a “Sludge Dewatering Pre-engineering Study” to define the general requirements of the sludge dewatering system and to evaluate the life cycle costs of the belt press and centrifuge systems. The study concluded that a centrifuge system is the recommended alternative for the District.

In October 2002, WBA prepared the procurement documents for the District to pre-purchase a centrifuge unit. The selection and award of the purchase order was based on the evaluated costs, which took into accounts of the equipment cost, projected system performance and 10 year projected O&M costs. The centrifuge unit was purchased in November 2002 and was delivered in July 2003.

In August 2003, WBA performed the detailed engineering design and prepared the construction documents for the District to construct a sludge dewatering system. The project includes a new centrifuge building, a sludge feed pump, a polymer preparation and feed system, a sludge cake pump system and associated civil, mechanical, control and electrical systems. The design of the system includes allowance for installation of a second centrifuge unit in the future. The design capacity of the dewatering system is 200 gpm feed sludge at 2% solids concentration. Construction of the sludge dewatering centrifuge system was completed in May 2004.

SELMA KINGSBURG FOWLER COUNTY SANITATION DISTRICT – Wastewater Treatment Plant Capacity Evaluation
WBA completed a capacity evaluation of the existing secondary treatment facilities at the Selma-Kingsburg-Fowler County Sanitation District (SKF) wastewater treatment plant located at Kingsburg, California. The existing facilities consisted of a large extended aeration basin with fine-bubble aeration equipment followed by four secondary clarifiers operating in parallel. The capacity evaluation was required because the portion of high-strength industrial waste in the influent was lower and the domestic waste portion was higher than used in the original design. A computerized model of the treatment facilities was used to predict the hydraulic and organic capacity of the existing facilities under various future wastewater loadings. The model was calibrated using actual treatment plant operating data for the year preceding the evaluation. The results of the evaluation included a table of treatment plant capacities for future combinations of influent wastewater flows and strengths under three different operating conditions (i.e., mean cell residence times).

The above projects are representative of our experience in this area.
If you would like additional information on these, or other projects that
we have completed, please contact us.