Unlocking Wastewater Value Is a Hidden Resource in Both Agricultural and Fermentation Processing
By Joel Stone, ConVergInce Advisers and Executive VP of Lee Enterprises Consulting & Thalia Aoki, Sales Engineer at ZwitterCo, Inc.
Special to The Digest
“Don’t throw out the baby with the bathwater.” This idiomatic expression characterizes the idea of tossing out the good along with the bad. Bioprocessing of agricultural or fermentation product businesses could be doing just that with certain of their wastewater streams.
Currently, some producers may not consider their wastewater streams as anything but a cost. However, there may be hidden resources in wastewater streams that can benefit the business. Or it could be that removal of organics may significantly reduce the cost of the waste treatment. Waste streams almost always contain organic components that, if they could be recovered, would reduce their WWT costs, and may also have value as a recycle or as an additional product. Processors may be unaware that there is an economical solution now available for recovering both fine insoluble and larger soluble components from their wastewater streams.
ZwitterCo, Inc. – an early-stage membrane company – has developed a breakthrough, patented membrane chemistry made specifically for the most challenging of separations.
The new ZwitterCo membrane offers precision organic rejection at low pressure without rejecting salts, and with exceptional fouling resistance. The performance of this membrane falls between traditional ultrafiltration and nanofiltration and is introduced as a superfiltration (SF) membrane. Refer to the following figure:
Wastewater and Sustainability
Wastewater refers to any non-potable aqueous effluent from sources including industrial process water, municipal, landfill leachates, and contaminated groundwater. Wastewater treatment is a process used to remove contaminants from wastewater and convert it into an effluent that can be directly reused (water reuse or reclamation) or returned to the water cycle with limited impacts on the environment.
Changing the balance between reuse and discharge of wastewater is becoming increasingly relevant. Most bioprocessing companies include sustainability as part of their mission, including not only carbon emissions, but also water use and reclamation. Wastewater reuse and water handling in general is a vital part of that goal. The challenge in scaling new processes often relates to the expense of the new products at scale. Recycling water and the potential recapture of nutrients out of the waste is an important element in reducing those costs. That recapture may also unlock the availability of addition product streams while also reducing effluent BOD and COD loads.
Local wastewater and freshwater restrictions often cap expansion capabilities, and thus revenue. As bioprocessing hubs expand, municipalities are taking on loading they were never built to handle, leading to further restrictions in many areas of the growing bioeconomy.
Resources in Wastewater
Water is a critical part of many industrial processes, but using freshwater comes at a cost for the business, as well as the environment. When possible, treating process wastewater for use throughout the plant can be a good cost- and environment-saving option. ZwitterCo now has an economical solution to help these bioprocessing and ag processing businesses better manage their wastewater streams.
Treated wastewater streams can be reused in the plant as an OPEX offset. Examples for uses of the recycled water throughout a facility include process water, non-potable demands, surface cleaning, landscape watering, and more. In some cases, the treated wastewater may even be able to be recycled in plant processes, decreasing the water needed for production. For instance, reclaimed water from spent fermentation broth containing residual biomass can be used to increase cell yields and improve production efficiency (1).
Another, sometimes hidden, resource in bioprocessing and agricultural product processing is organic product recovery, such as nutrients, proteins, and high value molecules. For some, this generates a purified mixture that enables higher product quality and yield or turns a discharge cost into revenue by creating a sellable byproduct:
• Currently, soy producers often discard waste soy, whey, and okara, which could be processed to recover nutrients suitable for animal feed or as additives for microbial fermentation (2).
• A common co-product in ethanol plants is distillers dried grains with solubles (DDGS), which is used as animal feed. Additional treatment of the wastewater residuals would increase protein yields and enhance the nutritional and economic value of the DDGS (3).
• One of the key limitations on the commercialization of cultivated meat is the high cost of growth medium. Often, a reactor may require complete replacement of medium before nutrients are completely depleted, due to acidification or the generation of inhibitory waste factors. Treatment of the discarded medium would allow recovery of these expensive additives (4, 5). In some cases, the residual biomass in discarded medium may itself be a valuable co-product, as in algal cultures, where residual algae can be used as a feed additive (6).
Current Options & Technologies
Previously, wastewater treatment has demanded multiple processes that require membrane separations, filtration, or other unit operations. The constant variability of highly fouling contaminants necessitates robust and reactive treatment processes, and the high concentrations of organic pollutants require using both aerobic and anaerobic digestion. Depending on the type and extent of the contamination, the treatment steps may include physical, chemical, and biological treatment processes. Biological digestion can be achieved with lagoons, membrane bioreactors (MBR), anaerobic digestion, and moving bed biofilm reactors (MBBR). Other possible treatment steps in the process are reverse osmosis (RO) and ion exchange.
When deciding on wastewater treatment at your facility, it is important to assemble experts knowledgeable about the technologies being evaluated and how to combine them to achieve required final effluent quality. These experts should understand the challenges of treating wastewater for recovery.
Challenges
The complex nature of wastewater can make it difficult to digest. Often large, expensive biological systems are needed. Batch operation and fluctuations in wastewater composition make it difficult to sustain biological communities.
The high presence of organic fragments including fats, oils, and grease (FOG), as well as chemicals, can inhibit biological activity, necessitating complex pre-treatment processes. These contaminants also cause standard RO membrane elements to foul easily, leading to extensive cleaning requirements. Traditional membranes can take hours of cycling between different chemical solutions to clean properly.
Many streams are so challenging that membranes were historically unable to be used, or simply a poor economic choice as they would foul and become unusable within days or weeks. In some cases, membranes can require so much cleaning that any reclaimed water is consumed just to keep them operating! Adding to the cost of these wastewater treatment options is the high energy requirement to aerate biological systems or supply necessary pressure to RO membrane lines.
ZwitterCo as the Solution
Membranes based on zwitterions can be the solution to unlock hidden resources in wastewater. A zwitterion (also known as an “inner salt”) is a molecule that has both a positively and a negatively charged group in close proximity. These charges pull water to the zwitterion while repelling organic components (like proteins, fats, and oils) that stick to traditional membranes and impede their filtration capacity. Refer to the following figure:
By linking these zwitterions together with a strong backbone, ZwitterCo was able to create extremely hydrophilic (“water-loving”) membranes that prevent organic components from adhering to their surface or clogging their pores.
ZwitterCo’s patented zwitterionic membrane can offer specific benefits in applications with extremely challenging feeds, like bioprocessing and agricultural product processing, where fouling resistance is critical. Finding a membrane that can handle the high levels of fats, oils, and proteins in these streams has previously been nearly impossible. Compared to current treatment options, processes using ZwitterCo SF membranes may offer benefits, including lower cost of ownership, smaller footprint, lower energy costs, reduced cleaning costs, longer uptime between cleaning cycles, and water reuse.
Conclusion
Wastewater is often a hidden resource center for bioprocessing and agricultural product processing businesses in water reuse or organic product recovery – and sometimes both. Talk to an expert to determine the best technology to use in your facility and take advantage of your options to turn a loss into a profit center. In short, don’t throw out the nutrients or water reuse value options with the wastewater. Unlock the value in what you otherwise would consider a nuisance, cost, or waste.
About the Authors
Joel is the President of ConVergInce Advisers and serves as Executive Vice President Strategy for Lee Enterprises Consultants, the world’s premier bioeconomy consulting group. He has been a long-term visionary and respected leader in commercialization of industrial biotechnology. ConVergInce is presently providing services for fermentation and downstream recovery to develop and commercialize the emerging synthetic biology products including commercialization assistance for advanced technology clients in renewable chemicals, biochemicals, biofuels, and agricultural and biobased ingredients for food, fragrance and consumer products. Joel has twice been listed in Biofuels Digests top 100 in the bioeconomy. In 2019 he was selected as the inaugural “Champion for Industry” award from Thomas.net. Contact: [email protected]
Thalia is a Sales Engineer at ZwitterCo, Inc. She has five years of experience in designing on-site freshwater and wastewater treatment systems for industrial clients. She has previously conducted research on produced water at the National Energy Technology Laboratory and recently gave a talk at the Groundwater Protection Council annual forum on Process Water Reuse for Industrial Manufacturers.
Contact: [email protected]
Sources
(1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7242880
(2) https://www.newfoodmagazine.com/article/77078/unlocking-additional-value-from-soybeans-via-the-circular-economy/
(3) https://www.nationalhogfarmer.com/nutrition/high-protein-ddgs-provide-high-quality-nutrition
(4) https://gfi.org/wp-content/uploads/2021/01/clean-meat-production-volume-and-medium-cost.pdf
(5) https://www.sciencedirect.com/science/article/pii/S096085241400618X
(6) https://www.sciencedirect.com/science/article/pii/S0960852418308885
Category: Top Stories, Thought Leadership
