A novel bio-nano process for energy efficient inland wastewater recovery

PI: Arup Sengupta
Co-PI(s): Derick Brown
University: Lehigh University

In cities and metropolis around the world, municipal wastewater after secondary treatment is being increasingly viewed as a large and resilient water resource that is insulated from climate change effects. In Orange County Water District (OCWD) in Los Angeles and San Diego in California, large treatment processes are in place to transform waste water into usable water. Total dissolved solids (TDS), a measure of salinity, normally varies between 500-1000 mg/L in municipal wastewaters globally. Thus, high energy-consuming reverse osmosis (RO) to achieve TDS reduction is the most significant treatment step for every secondary municipal wastewater recovery plant tried to date globally. For 150 million gallons per day (MGD) plant in OCWD in Los Angeles, energy consumption is 1.2-1.5 kWh for 1000 liters of treated water and 90% of it is due to RO. Also, nitrate and phosphate present in the RO reject are routinely discharged into the ocean.

We have developed a carbon dioxide (CO2) driven bio-nano wastewater treatment process that:

• transforms nitrate in nitrogen
• recovers phosphate as a high purity fertilizer
• reduces salinity without needing electrical or mechanical energy

Carbon dioxide at 10 atmosphere is used as the sole source of energy and the process produces no major disposable waste. In this project, the team will use treated wastewater from the Allentown plant and carry out the bio-nano process in our laboratory to demonstrate the feasibility of the process. The team already submitted a proposal to the US Bureau of Reclamation (USBR) and according to the review, they needed more convincing data from representative wastewater plant. Purolite Co in Philadelphia and Calgon Corporation in Pittsburgh became enthusiastic partners of the project and they are providing their products free of cost. The Leheigh team has a US patent pending on the CO2 induced desalination process. Once proven successful, the process can be rapidly scaled up and implemented in the field.