An innovative FOG-to-Biodiesel approach addresses a costly problem for the wastewater industry and also generates a new energy resource for treatment operations. Brian Levine of GreasezillaTM and Al Barbarotta of REA explain.

Fats, oils, and grease (FOG) waste is a serious and growing problem for the wastewater industry and the environment. Every year, grease costs municipalities millions of dollars in clogs, equipment damage, and sewer line repair. Not only is FOG costly to handle and remove, but it is also the primary cause of sewer backups.

The largest source of grease comes from restaurants and commercial kitchens. Ideally, grease is thoroughly wiped off all cookware and utensils prior to washing. In practice, however, it is faster and easier to remove the grease with hot water, particularly in a busy kitchen. Unfortunately, this means grease is going down the drain. Once it cools down in the sewer pipes, the grease begins
to clump and adhere to pipes. Over time, the grease blocks them altogether – causing backups and leading to serious public health and water quality problems.

The United States (US) Environ-mental Protection Agency (EPA) estimates that the annual production of collected grease trap waste and uncollected grease entering sewage treatment facilities
ranges from 363 kilograms (800 pounds) to 7,711 kilograms (17,000 pounds) per year, per restaurant. Add to that grease entering pipes from private homes and other industrial sources, and the massive amount of FOG accumulating in sewer lines leaves wastewater facilities struggling to remove and dispose of FOG before backups occur.

In response to the growing FOG problem, the EPA established requirements to control pollutants that could interfere with publicly owned treatment works (POTW). Additionally, municipalities are adopting and enforcing more stringent regulations for the handling of grease, mostly aimed at the foodservice industry. These regulations attempt to keep grease out of the sewage system, including specifying grease trap requirements and how frequently interceptor tanks are emptied.

The Danbury solution

The US state of Connecticut adopted FOG-management protocols, similar to measures getting adopted on the federal level, regarding how food service establishments and food processing facilities handle their grease.

Danbury, Connecticut, however, is taking an additional – and more innovative – approach to the issue with its new state-of-the-art FOG-to-Biodiesel receiving station for its wastewater treatment facility. By forming a strategic partnership with REA Resource Recovery Systems, LLC and Veolia Environment S.A., along with the University of Connecticut, Danbury developed plans for the station to handle FOG in a fiscally responsible and environmentally friendly way. The new addition will seamlessly integrate a FOG separator system and biodiesel reactor system into its processes, ultimately using the massive amounts of FOG waste to fuel the city’s heavy equipment.

The solution may change the way the wastewater industry looks at grease. The wastewater receiving station consists of three main parts: FOG receiving, FOG separation, and biodiesel conversion.

Step One: FOG receiving

Using a hub-and-spoke model, Danbury’s FOG receiving station will serve as the area hub for grease collection. REA selected technology from Greasezilla to be placed upstream, where it will handle grease on the front end, before it causes equipment and infrastructure problems. The system will assist Danbury in complying with EPA national pretreatment standards for POTWs, including CFR 40 403.2 and CFR 40 403.5 that strive to prevent pollutants from causing obstructions and other interference that might interfere with operations.

Greasezilla will take grease from haulers as well as scum grease that comes off clarifiers and oil skimmers from smaller area plants. The FOG entering the system will provide the raw material needed for the next step in the process.

Step Two: FOG separation

At the heart of the FOG receiving station, Greasezilla’s brown grease separator technology delivers a low-moisture, high FFA brown grease offtake, ideal for REA’s high-grade Biodiesel B100 conversion. The Greasezilla system can process up to 151,416.47 liters (40,000 gallons) of raw grease trap waste per day.

The two-tank, two-boiler system heats the FOG to create separation without the need for additives. Greasezilla heats the FOG waste, separating it into its basic elements, sending the water back to the treatment center headworks and recovering the brown grease as an advanced biofuel. The small amount of remaining organic debris can be incinerated or disposed with traditional methods.

From start to finish, a boiler heats the tank to a temperature up to 71 degrees Celsius (160 degrees Fahrenheit) and separates the FOG into three distinct layers:

1. Residual pasteurized effluent water, comprising approximately 80 percent of the material and nearly free of suspended solids, can be safely discharged into the treatment facility.

2. Batter, making up about 5 percent, can serve as an excellent feedstock for anaerobic digesters. It can also be treated with traditional processes or be processed with the effluent water.

3. Rich brown grease, comprising approximately 15 percent, is pumped into holding tanks and converted into a rich, advanced biofuel. Approximately 5 percent of the carbon positive biofuel returns to fuel Greasezilla and the other 95 percent can be used as a substitute for #6 bunker fuel. This fuel burns much cleaner than bunker #6 and is in demand because it meets IMO 2020 standards. In the Danbury case, Greasezilla’s biofuel will serve as a feedstock for the next step in the process.

Step Three: Biodiesel conversion

Once separated, the brown grease advanced biofuel harvested from the process, clear of organic solids and containing a low-moisture content of well below 1 percent, will be processed through the REA system and turned into biodiesel.

REA’s biodiesel conversion system was designed to process brown grease from FOG waste instead of higher-quality feedstocks that can be costly on the front end. With a smaller footprint than other biodiesel processes, REA’s system will process the feedstock into two different grades of fuel products for use by the city. The first is B100 biodiesel, which will fuel the city’s trucks. This grade biodiesel can also be used for heating purposes or emergency backup power. The residual biodiesel is a grade suitable for industrial heating oil or bunker fuel.

Danbury’s facility will have a continuous, automated process for taking the decanted grease and processing it at 2 liters (0.5 gallon) per minute. Annually, the Danbury station is scaled to generate 946,353 liters (250,000 gallons) of biodiesel. The system is fully automated and will run six days per week, with the seventh day set aside for routine machine maintenance.

The benefits

Turning waste into fuel doesn’t just deal with the messy problem. It is changing the way the wastewater industry looks at grease. Danbury is building a truck-to-truck FOG facility, where trucks unload FOG waste at the receiving station and a large amount of that waste leaves the facility as biodiesel for the city’s fleet of heavy equipment and trucks.

Once operational, the Danbury facility will provide a number of benefits to the community.

  • Grease collection: Haulers will have a new location to bring their loads. The receiving station will help haulers conveniently dispose of the vast amounts of grease trap waste they collect from commercial foodservice businesses.
  • Cleaner fuel: Estimated to generate approximately 605,666 liters (160,000 gallons) of B100 biodiesel annually, the facility is projected to produce enough biodiesel to fuel all the city’s heavy equipment with additional fuel to spare.
  • Cleaner environment: Not only will Danbury’s facility have a viable means of handling municipal grease and better preventing Sanitary Sewer Overflows, but the process will transform a readily available waste product into biofuel and then biodiesel, which burn far cleaner than fossil fuels. The city will use the biodiesel it generates, further reducing its dependence upon fossil fuels. Additionally, the Greasezilla system fuels itself with the same carbon positive biofuel it produces from its grease separating process.
  • Operating expenses: With fewer surprises from blockages and equipment repair, the Danbury facility’s annual operations and maintenance budget will be more stable and predictable. The facility will also generate revenue from tipping fees.

Danbury’s innovative way of handling FOG has already drawn the interest of other communities in the region.

The Danbury project is a result of years of research and careful planning. The FOG separation technology to be used in the facility is already in use at several installations in North and South America, with more municipalities planning to add the alternative Greasezilla technology into their wastewater facilities.

The Wareham Water Pollution Control Facility in Wareham, Massachusetts, US, implemented Greasezilla approximately two and half years ago. Not only has the system provided a viable and cost-effective way to reduce solids for disposal by managing FOG issues, but the facility helps haulers unload their grease trap waste.

Danbury’s innovative way of handling FOG has already drawn the interest of other communities in the region – leaving Greasezilla and REA to discuss plans for extending their joint efforts to other wastewater treatment facilities.