Clean Your Wastewater Before the City Does

March 22, 2011
Pretreatment technologies can pay for themselves in surcharge savings

Food plant wastewater is a constant concern for food & beverage plant operators. With many municipalities seeking to plug budget deficits or deal with rising energy costs, higher user fees are being considered or implemented across the country.

That’s not to mention the green movement, wherein just being able to say you wash less pollutants down the drain scores important points with consumers – and your own corporate sustainability officers.

Fortunately, new treatment technologies are on the way to reduce surcharges, improve the environment and, in some cases, create some usable energy in the process.

BioAmp from EcoBionics is a pretreatment system that focuses on biological (or biochemical) oxygen demand (BOD), an indirect measure of the amount of oxygen that will be removed from the water stream as bacteria consume the food products left in it.

The BioAmp unit meters up to 31 trillion live bacteria into wastewater every 24 hours. The bacteria consume the organic carbon sources – primarily sugars – plus fat, oil and grease in the wastewater before your municipal treatment plant measures the BOD of your waste for surcharges.

BioAmp is a small, cabinet-contained unit with stored, dormant bacteria in the form of pellets. It mixes the seed bacteria with their food source (nitrogen and phosphorus) until they begin propagating. It then meters them into wastewater collection systems in your plant.

Unilever, Stonyfield Wring Energy from Wastewater

A Unilever PLC ice cream factory in Hellendoorn, the Netherlands, this January began partial operation of a bio-digester that not only cleans its wastewater but converts waste products into energy. The bio-digester from Dutch company Paques (www.paques.nl) will cover 40 percent of the ice cream factory’s green energy requirements.

Construction of the biodigester began last year. The Biopaq AFR (Anaerobic Flotation Reactor) was developed for the anaerobic treatment of waste streams that contain fat, oil and grease or biodegradable solids such as proteins and starch. It converts the organic compounds into valuable biogas.

The unit can handle water streams with COD levels up to 100g/l. The integrated flotation unit ensures that biomass and not yet converted compounds are retained in the reactor, while biogas and purified water are extracted from the reactor.

It uses 24 billion micro-organisms to “eat” waste products and convert them into biogas. In this system, the food is byproducts and waste from ice cream production, such as milk, cream, proteins, syrups and pieces of fruit.

The Biopaq AFR is an all-in-one reactor, treating the wastewater in one compact reactor, whereas conventional systems would use a number of processing stages, Paques officials claim.

The company also notes the bio-digester supports Unilever’s Sustainable Living Plan aimed at reducing waste and the consumption of water and energy. The bio-digester is expected to become fully operational at midyear.

The Unilever system is similar to one installed at Stonyfield Farm, Londonderry, N.H. “When our factory grew to a point that we needed to pre-treat this wastewater before it left the ‘Yogurt Works’ and headed to the municipal treatment plant, we knew we wanted to use a very environmentally responsible type of treatment — one that didn’t require a lot of energy or chemicals or generate a lot of waste,” says a spokesman for the company, which has a storied history of environmental responsibility.

“A traditional dairy wastewater treatment plant uses quite a bit of energy and generates biosolids that need to be hauled offsite to be managed. While it was not the typical choice for a dairy company, we chose our anaerobic digester because it generates very little waste, yet makes some of its own energy.”

The Stonyfield system, which also creates biogas, was installed by ADI Systems.

“The upfront cost was 17 percent higher than other systems, but the operating costs are much lower, due to 40 percent less energy use and more than 90 percent less waste generated (and therefore 90 percent less waste to pay to have hauled away!),” says the spokesman. “We expect it to save $3.5 million over the first 10 years of operation.”

With a minimum two hours of reaction time (four to six hours is ideal), the bacteria will eat enough waste in the wastewater to reduce the BOD demand before the wastewater reaches the municipal treatment facility.

The unit needs to be serviced – essentially, the seed bacteria replenished – about once a month. “The unit can pay for itself in surcharge reductions,” claims Glenn Cramer, technical sales manager.

Clean Water Technology Inc. offers a number of waste treatment technologies, most focusing on solid/liquid separation processes. “Our patented technologies [include] mixing flocculation and flotation, cutting-edge biological reduction technologies and wastewater system peripherals, which include screen filtration units and automated chemical delivery systems,” the company states.

One CWT technology is the Moving Bed Biofilm Reactor (MBBR), which consists of thousands of polyethylene biofilm carriers operating in mixed motion within an aerated wastewater treatment process.

When communities of microorganisms grow on surfaces, they are called biofilms or biocarriers. Every biofilm carrier adds to productivity by providing an active surface area, which sustains bacteria within protected cells. This high-density population of bacteria creates the biodegradation within the system.

Biocarriers are suspended in the wastewater of the reactor and are in continuous movement within a tank or reactor of specified volume. Biofilm, growing within the internal structures of the biocarriers, degrades dissolved pollutants in the wastewater stream. The pollutants that need to be removed to treat the wastewater are food, dissolved sugars or other various substrates, which contribute to the growth of the biofilm.

An aeration grid located at the bottom of the reactor supplies oxygen to the biofilm along with the mixing energy required to keep the biocarriers suspended and in constant movement within the reactor. Treated water flows from reactor into a grid or a sieve, the purpose of which is to retain the biocarriers within the reactor.

“Microorganisms in a biofilm wastewater treatment process are more resilient to process disturbances compared to other types of biological treatment processes,” CWT claims. “Thus, biofilm wastewater treatment technologies can be considerably more robust than other technologies.”

BioWish is the name of both the technology and the company supplying a novel wastewater treatment process. It combines a broad spectrum of microbial enzymatic activities with a complement of non-enzymatic, biocatalysts/cofactors, which work together to enhance overall digestive reaction rates. The result reduces odor, volatile organic compounds (VOC), BOD, COD and overall solid waste.

BioWish can reduce sludge production and handling by up to 60 percent due to accelerated digestion of organic waste. Its long list of claims includes: lower aeration requirements (30-50 percent less) for energy savings, increased biological efficiency in nutrient removal, lessened need for chemical additives, reduced odorous emissions and other volatile organic compounds, rapid removal of fats, oils and greases, plus suspended solids, nitrogenous waste and a wide range of contaminants; and overall efficiency improvements of wastewater treatment plants, oil separators, grease traps and dissolved air floatation units.

At the back end of this process, Hach Co.  provides the tests -- from laboratory to on-line measurement -- to provide operators with the data needed to make informed changes to their process ensuring permit compliance.

“There is not a ‘one measurement fits all’ parameter,” says Mike Kilner, Hach’s applications development manager for industrial process and municipal wastewater. “By careful review of the waste stream we can determine the proper measurement method.”

But Hach tends to focus on chemical oxygen demand (COD), which it claims provides faster results than BOD testing. COD is a correlative/early indicator of BOD levels, and some permits include COD as a surrogate for BOD. (See our Hach Knowledge Center for more information).