Session 15A: Wastewater Process: Nutrient Removal
1:15pm - 2:00pm
Planning for Nitrogen Removal in King County
1Brown and Caldwell; 2King County WTD;
The Washington State Department of Ecology (Ecology) has been evaluating the impact of nitrogen on dissolved oxygen concentrations in Puget Sound for over a decade. More recently, Ecology has taken steps towards implementing nitrogen limits on wastewater treatment plants (WWTP) that discharge into Puget Sound, and has begun to implement nitrogen load action levels on WWTPs as part of a nutrient general permit process that would trigger sequential tiers of nitrogen removal upgrades. King County operates three large, regional WWTPs (West Point, South Plant, and Brightwater) that discharge directly into Puget Sound. To better understand nitrogen removal options, costs, and other impacts, King County completed an evaluation of the potential for implementing various nitrogen removal options at these three WWTPs.
To evaluate nitrogen removal potential at the different facilities, pre-screening of over twenty different nitrogen removal, sidestream treatment, and intensification technologies was first completed, considering cost, nitrogen removal capabilities, greenhouse gas emission (GHG) potential, and other screening criteria. Then, pre-screened technologies were evaluated for various nitrogen removal scenarios for each facility, such as adding sidestream treatment only or meeting a range of seasonal or year-round effluent total inorganic nitrogen targets.
Potential conceptual site layouts and sizing for the alternatives for each scenario were developed based on modeling with calibrated process simulators. The results were used to identify a range of potential capital/operating costs, footprint requirements, and GHG emissions for each nitrogen removal scenario. In general, the results showed that capital/operating costs, GHG emissions, and footprint increase as the level of nitrogen removal increases, with some exceptions. The results also demonstrated that all three WWTPs have potential footprint limitations for nitrogen removal. This presentation will discuss the methods and results for the various effluent nitrogen removal scenarios for each of the three WWTPs.
2:00pm - 2:45pm
Construction, Commissioning and Start Up of the World’s First Advanced Biological Nutrient Recovery (ABNRTM) Facility at the Village of Roberts, WI
CLEARAS Water Recovery, United States of America;
As wastewater treatment facilities face the challenge of selecting long-term and cost-effective solutions to meet more stringent discharge permit requirements, resource recovery has become a vital component for consideration. This presentation will highlight the construction, commissioning, and startup of the world’s first Advanced Biological Nutrient Recovery (ABNR™) by the Village of Roberts, WI to meet their ultra-low-level total phosphorus discharge limit of 0.04 mg/L.
Prior to integration of ABNR, the Village of Roberts utilized alum for chemical phosphorus removal to meet a discharge limit of 1.0 mg/L total phosphorus. To meet compliance, Roberts explored source minimization, facility optimization and performed a centrate evaluation, only to achieve 0.41 mg/L. Further exploration of facility modifications, led to piloting cerium chloride, ultra-filtration and ABNR. CLEARAS ABNR was the clear choice in consistently meeting future limits.
The Roberts ABNR facility is designed for 0.150 MGD and 4.0 mg/L TP. ABNR allowed the facility to leverage existing infrastructure and eliminate upstream chemical phosphorus removal resulting in cost savings. The flexibility of ABNR has also given Roberts the opportunity to plan for increased nutrient loadings from a future septage receiving program with a phased approach. See Figure 1.
Resource recovery has become critical to the wastewater industry and the CLEARAS process integrates the core principles of this concept. ABNR maximizes existing treatment infrastructure, extends the life of existing assets, allows for optimization of secondary treatment processes resulting in cost savings and residual algae-based sales. ABNR is a sustainable solution that enables wastewater treatment plants to transition to resource recovery facilities. In addition to the Roberts, WI project, ABNR has been pre-selected for three additional full-scale projects (two in WI and one in UT) which will be constructed in 2021 – 2022.