City of Banning, California – Nitrogen Removal Feasibility Study


Groundwater is one of the main drinking water sources for the City of Banning. One of the serious problems that affects the quality of the region’s groundwater is the leaching of nutrients from the soil. Nitrogen easily percolates into groundwater via rainwater recharge, irrigation water carrying excess fertilizers, and untreated sewage or septic leaching. If nitrogen concentrations in the drinking water are above the regulated Maximum Contaminant Level (MCL), serious human health effects may occur, particularly in infants below the age of six months. Additionally, high nitrogen concentrations can result in the formation harmful byproducts when contaminated water is combined with chlorine for disinfection.


The City of Banning utilizes a 3.6 Million Gallons per Day (MGD) municipal wastewater treatment plant that was not in compliance with a proposed 10 mg/L Total Nitrogen (TN) effluent limit and Title 22 recycled water guidelines. Montrose was contracted by the City to assess and determine the actions that would enable the city’s facility to achieve the compliance targets.


Montrose provided site assessment, alternative analysis and modeling toward the objective of achieving regulatory compliance. The evaluation included design, modeling and cost estimates for a Membrane Bioreactor (MBR), conventional activated sludge, trickling filter improvements, Integrated Fixed Film Activated Sludge (IFAS), a Moving Bed Biofilm Reactor (MBBR), tertiary filters, and chlorine disinfection. Ultimately, the Montrose team recommended an MBR system for implementation in order to get back into compliance. The team is continuing to work closely with city officials to further define the project, explore possible variations, and determine cost estimates.

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