Case study: First Ultra PX for wastewater treatment yields high-performance savings

Sept. 26, 2023
Eliminating toxic wastewater and saving $186,000 per year.

One of the most rewarding parts of my job is assessing the suitability of a particular market and/or application for Energy Recovery, providing my recommendation and a toolkit to our business development and sales teams, and then hearing the customer’s reaction after installation.

At Energy Recovery, we are constantly conducting research to capture the unique needs of our wastewater customers and measuring the performance of our pressure exchanger (PX) technology across various applications. Recently, we conducted a case study at a lithium cathode wastewater treatment facility in the Hubei Province of central China to measure the energy savings and value after installing the PX and Ultra PX Pressure Exchangers.

The challenge: Eliminate toxic wastewater without increasing costs

China has made water conservation a key priority and is ramping up regulations around wastewater discharge, limiting both the concentration of contaminants and discharge volume. Industrial wastewater treatment is a crucial — but oftentimes expensive — process. A lithium iron phosphate (LFP) cathode manufacturing facility in the Hubei province of central China needed a cost-effective, high-performing solution to treat its wastewater for reuse while producing this critical component used in electric vehicles globally.

The site produces 50,000 tons of LFP annually for large lithium-ion battery manufacturers, resulting in a combined waste stream with approximately 160,000 mg/L of total dissolved solids containing ammonium sulfate and ammonium phosphate. To tackle this problem, the facility enlisted Sinochem Memtech Co., Ltd — a subsidiary of Sinochem International and an innovative enterprise focusing on membrane solutions for the water treatment industry — to design a facility using a combination of technologies to treat the waste stream.

By employing two reverse osmosis (RO) stages and an ultra high-pressure reverse osmosis (UHPRO) stage, Sinochem reduced the brine waste flow rate by 90% before using a thermal process on the remaining flow to reach zero liquid discharge (ZLD). However, these critical processes would normally require high energy consumption, making it harder to achieve cleaner operations without incurring prohibitively high costs.

When the Energy Recovery team enters a new market, educating the customer is a key priority because the PX and Ultra PX Pressure Exchangers are new technologies. We strive to educate the market or industry not only on the value of the pressure exchangers, but also of RO membrane processes. In this instance, we worked closely with the China sales team to ensure our offering was robust and maximized the value to Sinochem.

The solution: Coupling the PX with the Ultra PX for maximum energy efficiency

Sinochem chose the PX Pressure Exchanger for the second RO stage and the Ultra PX (flow ranging from 4.5 to 13.6 m3/hr and specifically designed to operate in an ultra high-pressure environment up to 120 bar) for the UHPRO stage to capture energy otherwise wasted in these high-pressure processes.

The combination of these technologies significantly lowered overall energy consumption for wastewater treatment, allowing the site to drastically decrease both operating and capital expenses, and dramatically reduce the investment in the thermal system. As an added benefit, treated wastewater is also now circulated back into the battery production facility, creating a closed water system that significantly reduces water consumption and associated costs. The concentrated waste stream was also valorized through the sale of ammonium sulfate and phosphate for the fertilizer industry.

This was a great success for Sinochem and it felt tremendous to know that our recommendation was accurate and that the Energy Recovery team could seamlessly install and oversee the project’s success from start to finish and beyond. It was even more satisfying to find out the field data confirmed what we had promised after the PX and Ultra PX were installed.

The result: Cleaner operations without higher energy consumption

This site was the first to commission an Ultra PX in early 2022 — therefore, rigorous site visits were conducted to confirm performance of the Ultra PX. While the facility has yet to ramp up to its full capacity, under real-world operating conditions, the PX achieved an efficiency of more than 95%, and the Ultra PX an efficiency of more than 93%. With these savings, the payback for the equipment will be less than two years even at reduced feedwater levels of total dissolved solids (TDS).

One of Energy Recovery’s most important processes during project reviews is continuing to collect field information, voice of customer (VOC) and other data. We recently visited the site in China to speak with the plant operators and get their feedback on, and experience with, the PX. Their feedback was overwhelmingly positive — after commissioning and system tuning, the PXs have been operating flawlessly for more than six months.

The plant will continue to increase production as the rest of its upfront processes come online. As this takes place, we expect to see increased system pressures and even better performance from the PXs.

Eric Kadaj is the senior director of market and applications development at Energy Recovery. For more than 20 years, Eric has applied his engineering and technical expertise to drive greater sustainability within desalination and the industrial wastewater space, including process design and implementation, operational strategies and novel discoveries that minimize environmental impacts.

Energy Recovery