Adapting centralized system technology for decentralized systems

 
As large centralized wastewater treatment centers are taxed by long pipelines, energy costs and adding new customers, UC Berkeley researchers are looking to decentralize systems when they can and safely provide water in new ways. But one of the hurdles has been taking technology that works on a large-scale capacity and fitting it into a micro-environment, which isn’t always as simple as making everything smaller.

Doctoral student James Barazesh tackled that problem and created a point-of-use device that mimics ultraviolet light/hydrogen peroxide (UV/H2O2) treatment processes used in a centralized water treatment facilities and makes it work at the household level.

“This makes a useful technology easily accessible to a greater audience, whether it’s a home, an office park or an apartment complex,” says Barazesh. “It’s a great tool because it’s compact, inexpensive and runs exclusively on electricity.”

UV/H2O2 has long been used as a treatment process to remove contaminants at centralized water treatment facilities. The problem, however, was trying to effectively use the same technology in small-scale settings, like office buildings, apartment complexes, or off the grid houses, where transporting and storing hydrogen peroxide makes it an impractical solution.

Barazesh, working towards a doctorate in electrochemical water treatment, was asked to generate hydrogen peroxide on-site as an alternative to transporting it to small, decentralized treatment systems. He was set the task by Berkeley Water Center (BWC) Co-Director David Sedlak, who has been working on finding less expensive and more accessible ways to use hydrogen peroxide in water treatment.

 

The compact electrochemical cell intercepts water before it hits the faucet. As contaminated water flows into the device, it passes into a cathode where hydrogen peroxide is created from oxygen in the ambient air. The hydrogen peroxide passes into a small scale UV reactor that produces oxidizing radicals that removes contaminants, before finally being sent back into the anode of the cell where the water is aesthetically polished to drinking water standards.

While hydrogen peroxide is used at centralized facilities to remove contaminants on a scale of 70 million gallons of water per day, this technology is able to produce 120 liters per day, enough for a household, at a low cost and without auxiliary chemicals.

Barazesh initially worked with BWC post-doctoral researcher Tom Hennebel, building upon the initial design, which was a handcrafted cartridge. Barazesh improved the design and was able to more efficiently produce the cartridges on campus in the machine shop, making a modular design that could easily be tailored to specific treatment goals, including pollutant removal and nutrient recovery.

Barazesh said as the device was designed for use in decentralized treatment, it had to be able to produce hydrogen peroxide in complex solutions likely to be encountered at a decentralized level, including surface water, groundwater, and wastewater effluent. Furthermore, it had to be able to remove low concentrations of pharmaceuticals and contaminants present in the water.

“We tested the point of use device with several different waters, and hydrogen peroxide production was independent of the type of source water despite substantial variability in their compositions. We observed greater than 80 percent removal of pharmaceuticals even in the complex wastewater effluent solution,” says Barazesh.

Now, as consumers and developers look for innovate ways to increase water efficiency and sources as new homes and offices are being built, there is one more piece of technology at their fingertips to explore.