BCR Featured Project
CleanB® – City of Alachua, Florida
In 2009, BCR brought to market the costeffective CleanB solution as an alternative to aerobic and anaerobic digestion. The City of Alachua installed a CleanB system to avoid digestion, eliminate odor issues, and reduce overall costs.
The City of Alachua, Florida, was in the process of building an advanced wastewater treatment plant (WWTP) to process 0.6 MGD ADF (permitted 3.0 MGD). Alachua decided to evaluate the CleanB system as an alternative to standard aerobic digestion.
Alachua’s existing biosolids process consisted of aerobic digestion prior to dewatering. The digested and dewatered sludge was then hauled offsite for landfill disposition. The blower and mixer system (40+ hp, operating 24 hrs/day) cost approximately $35,000 per year in energy costs. Landfill costs were approximately $60,000 per year. Land application was not an option because of odor and pathogen control issues.
The CleanB® Solution
BCR proposed a CleanB solution at the Alachua facility to avoid the need for the digestion, eliminate odor issues, produce a Class B residual suitable for land application, and reduce overall costs to the City.
CleanB is a simple, one-stage process that meets pathogen and vector attraction reduction requirements as defined by 40 CFR Part 503. The system is modular and highly scalable, has a small footprint, and may be mobilized or permanently installed onsite. Every CleanB system is outfitted with a control system and monitoring devices to record process parameters and ensure consistent, repeatable biosolids treatment.
A CleanB system was integrated at Alachua as follows:
- One existing aerobic digester was utilized as a sludge holding and decant tank.
- The CleanB unit was incorporated beetween the sludge holding tank and the existing centrifuge.
- The CleanB system utilized existing yard piping to ensure 10 minutes of chemical contact time.
Following CleanB treatment, dewatered, Class B biosolids were hauled offsite for land application or composting at a regional facility. The CleanB system provided multiple advantages over Alachua’s previous residuals treatment system, including:
- Substantially improved odor control
- Treatment of sludge to Class B standards as defined by CFR 40 Part 503
- A 30+% reduction in dewatering polymer consumption
- A 28% increase in total solids after dewatering
- Significantly reduced energy consumption
- Increased sludge processing capacity
- Elimination of landfill tipping fees
City of Alachua Financial Analysis
The City of Alachua and its engineers completed an in-depth financial analysis comparing the existing biosolids process to BCR’s proposed CleanB solution. The City estimated that it would receive a $1.42 million economic benefit over a 20-year period by implementing the CleanB system.
Cumulative Biosolids Management Costs
Savings to the City – 20-Year NPV
Based on the in-depth financial analysis, BCR and Alachua estimated that the City would save $2.73 million in cumulative biosolids management costs over the next 20 years. This cost savings translated to a $1.42 million economic benefit based on a 20-year Net Present Value (NPV).
Customer Monthly Rate Impact
Savings to Customer – 20-Year NPV
The biosolids management cost savings to the City translated to a direct economic benefit of $386 to each ratepayer based on a 20-year NPV. Monthly rates were estimated to be reduced by $1.26 per customer in 2011, increasing to a savings of $4.82 per customer per month by 2031.