Case Study: City of Watsonville, CA WWTP

APG-Neuros’ Turbo Blower reduces energy consumption, while improving the working environment

The City of Watsonville replaced one of its centrifugal blowers with a new APG-Neuros NX Series turbo blower combined with replacing its coarse-bubble diffusers with more efficient fine bubble aeration diffusers. The new turbo blower supplies the majority of aeration, while the three remaining centrifugal blowers serve to meet peak flows and provide redundancy.

Project Background
The new fine bubble diffusers have a higher design Oxygen Transfer Efficiency (OTE) than the pre-existing system, requiring less air. The existing multistage blowers could not be modulated to reduce the air supply to meet the new requirement The new Turbo Blower NX150-C100 enabled the system to modulate the amount of air going into the aeration basins responding to a Dissolved Oxygen (DO) level setpoint. The new Turbo Blower saves energy by providing the amount of air needed for the aeration process with the ability to meet the lowest aeration requirements without blowing off excess air.

Project Development
The City of Watsonville, MISCOwater and APG-Neuros working together, identified the opportunity to reduce the wastewater treatment plants energy costs and improve the process. MISCOwater and APG-Neuros utilized the facility’s trend data and the diffuser supplier’s data to estimate air flows required and the facility’s drawings to calculate pressure losses in the piping and confirm installation requirements. The collaborative efforts between the customer, MISCOwater and APG-Neuros resulted in a seamless and successful turnkey project at a minimum cost. The total project cost was $155,078.94.

Results
The baseline energy usage of the diffusers and blowers represented 70% of the total site electric usage for the last twelve months of utility billing data. The energy savings resulting from the blower and diffuser upgrade project resulted in 74% savings of the baseline energy usage, or approximately 52% of the total plant energy usage.
The local utility provider, Pacific Gas & Electric Company (PG&E) and City of Watsonville estimate the replacement of one blower will save $47,395.26 reducing power consumption by 526,620 kilowatt-hours (kWh) per year. The corresponding approved rebate was $79,210.70 for the aeration upgrade, where $40,792.00 was the total incentive for the turbo blower replacement alone. PG&E’s final analysis confirmed the energy savings exceeded the initial project estimates.

Payback
The payback period is <3.3 years without energy rebate and <2.4 years with energy rebate.
Source: Pacific Gas and Electric Company Customized Retrofit-Demand Response Installation Review #2K1363615C