By Shannon Grant
The world relies on water in order to produce the products people use every day. Whether it’s the food we eat, the beverages we drink, the clothes we wear, or the paper and chemical products we use, water is required for nearly every step of production.
The resulting wastewater must be carefully managed. One option is to discharge untreated wastewater to the local municipal treatment plant, but with that comes considerable cost. The other - often more favorable - option is to treat wastewater at the processing plant itself.
Why Invest in On-site Wastewater Treatment?
On-site wastewater treatment presents a number of potential benefits, including:
Public Image: Today, conscientious consumers are more likely to purchase products that have been produced using sustainable methods, including responsible wastewater treatment. On-site wastewater treatment can help demonstrate environmental stewardship, thereby improving public perception of the company.
Compliance: Arguably one of the biggest motivators for industrial processors to invest in on-site wastewater treatment is environmental compliance. Effluent discharge laws are a necessary environmental protection measure designed to keep the world’s freshwater sources clean and readily available. The future of industrial processing depends on this, which explains why tougher penalties are being imposed for improper disposal.
Cost Savings: Wastewater disposal costs, once a minor operating expense, have risen dramatically, prompting cost-conscious plant managers to revisit their approach to wastewater treatment. Installing on-site solutions can reduce - even eliminate - surcharges incurred by sending wastewater to a municipal treatment plant. Better yet, the right technology can also reduce sludge hauling, chemical, and electrical costs.
Flexibility: The increased volume and strength of the wastewater following a production increase usually correlates with higher costs for off-site treatment. Investing in on-site wastewater treatment allows processors to handle the additional wastewater flow and load when production increases and/or when new product lines are introduced, helping the business to grow to its full potential.
Resource Recovery: On-site treatment can help processing plants do more with less. Instead of considering wastewater a problem, progressive companies are redefining wastewater as a resource in its own right. On-site treatment technology can be used to recover valuable resources such as clean water, power, and nutrients from wastewater.
Targeting Energy Neutrality
All industries are feeling the pressure to become more energy efficient. When it comes to wastewater treatment, this can often be accomplished with anaerobic digestion systems. Anaerobic digestion of wastewater produces valuable biogas, creating an incredible opportunity to convert waste into energy, further reducing operational costs and dependence on external energy sources.
Biogas captured from anaerobic digestion can be used in boilers to produce heat, burned in cogeneration engines to produce both electricity and heat, or, in some cases, sold back to the energy network for utility credits. Capturing methane with a gastight cover also reduces the harmful greenhouse gas emissions associated with energy production and use.
In the face of global water scarcity, companies are wise to implement on-site technologies to lower their water footprint. Wastewater can be a vast resource if reclaimed properly. High-quality, polished effluent can be reclaimed to improve overall water use ratios at industrial processing plants.
The level of treatment depends on the intended use, with non-potable applications requiring significantly less treatment. Reclaimed wastewater can be used in cooling towers, to clean equipment, and to irrigate crops and fields. The right treatment process opens doors to potable water applications as well.
Many types of processing wastewaters are full of nutrients, including nitrogen (N) and phosphorus (P), that don’t need to go down the drain. Nutrient-rich biosolids from wastewater can be recycled as a fertilizer to enrich soil, helping to grow and protect agriculture. Making better use of wastewater sludge places essential nutrients and water back into the soil, while reducing hauling costs and associated emissions.
How to Choose the Right On-site Wastewater Treatment Solution
Even after being sold on the benefits of on-site wastewater treatment, many industrial processors are not sure where to start when selecting an appropriate technology. Many factors come into play when selecting or upgrading wastewater treatment technology, including:
- Type of wastewater
- Regulatory requirements
- Operating conditions
- Site space limitations
- Ease of operation
One way to achieve environmental and economic wastewater sustainability is through biological treatment. Biological wastewater treatment uses naturally-occurring microorganisms to feed on complex organic matter, converting it into simpler substances. This type of treatment is divided into two broad categories: anaerobic treatment and aerobic treatment.
Anaerobic treatment, often known as anaerobic digestion (AD), is a process in which microorganisms convert organic matter into biogas in the absence of oxygen. It is an energy-efficient process that is typically used to treat warm industrial wastewater containing high concentrations of biodegradable organic matter.
With aerobic treatment, aerobic biomass in the presence of oxygen converts organics in the wastewater into carbon dioxide and new biomass. Depending on wastewater strength, aerobic systems can act as stand-alone systems for treating raw wastewater, or provide polishing of anaerobically pretreated wastewater.
The table below provides general guidelines of how anaerobic treatment and aerobic treatment differ.
The following two examples present practical applications of on-site wastewater treatment.
Local Authorities Require Confectionery Manufacturer to Pretreat Wastewater
A confectionery manufacturer located in Virginia was planning an expansion that would increase its plants’ wastewater flow and load. An overloaded publicly owned treatment works (POTW) led local authorities to require wastewater pretreatment in order to meet discharge limits.
Faced with having to establish on-site wastewater pretreatment at its facility, the confectionery manufacturer chose an anaerobic system with aerobic polishing designed and installed by ADI Systems. Several years later, production at the confectionery plant increased yet again, at which point ADI Systems added treatment capacity to handle 24 percent more flow and load.
The project had a tight schedule, but work was successfully completed on time and within budget. The on-site treatment solution allows the confectionery company to successfully meet discharge limits, while lowering operating costs and controlling foul odors from wastewater. Biogas produced in the anaerobic system is now burned in a process boiler to save on energy use and help reduce the plant’s carbon footprint.
Snack Manufacturer Eliminates Sewer Surcharges with MBR System
A major regional snack food manufacturer based in Alabama was producing more than 20 million pounds of snack foods per year, equating to 100,000-350,000 gallons per day of wastewater. The company was permitted to release the wastewater to the local sewer; however, that choice resulted in expensive surcharges.
If the snack food manufacturer could lower total suspended solids (TSS), biochemical oxygen demand (BOD), ammonia-nitrogen (NH3-N), and dissolved oxygen (DO) concentrations to prescribed amounts, it could bypass the sewer system altogether and discharge treated effluent to a small receiving stream.
ADI Systems’ membrane bioreactor (ADI-MBR) was selected because the technology fits within a compact footprint and consistently produces a high-quality effluent. The aerobic on-site wastewater treatment system offers an attractive payback on savings in surcharge fees imposed by the local POTW.
Effluent treated on-site can now be directly discharged to a small stream located adjacent to the plant, saving the snack manufacturer money by avoiding sewer surcharges. The clean effluent enhances the downstream environment by increasing the water flow within the small watercourse, beneficially impacting the local ecosystem.
As this article demonstrates, industrial processors can benefit by investing in on-site wastewater treatment technology. To determine the best solution for your facility, it is best to enlist advice from a wastewater treatment specialist that can offer a customized solution to meet your plant’s unique needs.
About the Author: Shannon Grant is the president of ADI Systems, a world-leading supplier of industrial wastewater treatment and waste-to-energy solutions. He is the author of over 70 technical papers on biological industrial wastewater treatment using proven anaerobic, aerobic, and/or membrane bioreactor processes.