Atlantic Treatment Plant Expansion, Solids Handling Improvements & Energy Recovery System
HRSD selected HDR to provide engineering services for the expansion of the 36 MGD Atlantic Treatment Plant (ATP) to 54 MGD capacity. As part of the preliminary design phase, HDR evaluated concepts that would provide lowest life-cycle costs and improved service. Increasing the efficiency of the solids handling system was a priority.
The ATP employed a labor-intensive dewatered cake handling system. Working with HRSD, HDR relocated the centrifuges to a new building adjacent to the cake storage pad. This eliminated the cake hauling operation, saving HRSD more than $350,000 in annual O&M costs. The new gravity belt thickeners were installed where the centrifuges were located, avoiding the need to construct a new thickening building.
HDR developed design plans to convert the existing digesters into a two-stage acid-phase digestion system. By employing this digestion process, the ATP increases volatile solids reduction by 10 percent, saving HRSD more than $150,000 annually in land application and dewatering chemical costs.
Construction of a new combined heat and power (CHP) system to capture and clean the digester biogas will be completed in 2012. The biogas will be split between new internal combustion engine generators for power production and heat recovery and the existing boilers for digester and building heating. The energy cost savings for the digester gas CHP system is $245,000 per year.
Based on design flow and estimated gas production, the installation includes 2.4 MW of generation capacity with three digester gas-rated 800 kW generators and is estimated to supply more than half of the plant's power demand, generating 13 million kWh/year of clean, renewable energy. HDR assisted HRSD in obtaining state funding in the form of low interest loans with principal forgiveness to help offset initial capital cost for implementation.
- 2012 - National Recognition Award, Engineering Excellence Awards, American Council of Engineering Companies