Industrial Utility Efficiency

# Wastewater

## Controlling DO: A Good Average Isn’t Good Enough

Most control systems use Proportional-Integral-Derivative (PID) algorithms for controlling DO, basin air flow distribution, and blower pressure or flow. These algorithms are prone to hunting - the cyclic fluctuation of the controlled variable. Fluctuations that oscillate the DO several mg/L above and below the target DO concentration are common.

## Considerations for Temporary Blower Air at a Wastewater Treatment Facility

This article aims to discuss the various technologies of equipment that could be presented to a wastewater operator faced with a temporary need for blower air and to help the operator understand the impact (both monetarily through a “Total Cost of Rental” approach and environmentally) of their decisions.

## Design Engineering a WWTP Expansion with Unique Site Constraints

A small site located within a floodplain, prone to erosion, and currently occupied by an existing in-service wastewater treatment facility is not at the top of any engineer’s list for a desirable site to expand a wastewater treatment plant or reclamation facility. However, these challenges created opportunity for specialized solutions during the design of the facility expansion; in particular, in designing the aeration and digester blower system.

## WWTP Saves Energy in Biogas Recovery Process

Ever since it was commissioned in 1974, the Echallens wastewater treatment plant in the Swiss canton of Vaud has been generating power from the recovery of biogas. In May 2020, two old oil-lubricated piston compressors used to mix the sludge in the digester were replaced by one MINK claw compressor from Busch Vacuum Solutions. This enabled the amount of power required for this process to be reduced by up to 40 percent. For the director of the treatment plant, this means he needs less energy to produce energy.

## Rethinking Aerobic Digestion Resolves Frustrations, Improves Performance, and Saves Money

Aerobic digestion is a common treatment technology used at small-to medium-sized wastewater treatment plants for the treatment of waste activated sludge (WAS). The objective of aerobic digestion is to treat the sludge for disposal, and for those trying to meet Class B biosolids, further reduce volatile solids (VS) and pathogens to ensure the sludge is suitable for land application.

## Three Different Sized Wastewater Treatment Plants Save Energy and Maintenance Costs with Aeration Blower Inlet Filter Upgrades

Optimized intake filters can save thousands of dollars annually in energy savings and may not require construction crews, engineering bids, or grant applications. The benefits can also be realized for treatment plants of all sizes. Described below are examples of three wastewater treatment plants that upgraded filters and came out ahead: a small rural operation with positive displacement (PD) blowers, a suburban plant using multi-stage blowers and a large urban plant that had already upgraded to airfoil bearing high-speed turbo blowers.