By Mark Wiertzema
Summary: With heightened emphasis placed on environmental effects of plumbing systems as well as water conservation, the industry has begun to meet these challenges. The ultimate goal is to see that water quality for all is ensured through safe and efficient systems via strict standards and policies.
Two decades ago, plumbing industry professionals might have simply responded with a puzzled look when the above topic was addressed. As the country has evolved slowly toward emphasizing long-term concerns of short-term solutions, water is now viewed as a valued and limited resource. And what brings water in and out of facilities? Plumbing systems.
Plumbing industry professionals don’t just look for the most cost-effective and efficient way to install systems in major facilities like restaurants, hotels and food processing operations. The current environmental and political climate of the continent—and indeed the world—is increasingly putting pressure toward water conservation and protection at the source: plumbing system installation and wastewater treatment.
Taking a look back
Historically, availability of water was viewed as a quantitative issue. Water management has thus focused on dealing with droughts and floods. With a growing population and increasing demands for multiple water uses, availability is now measured in terms of quantity and quality—both are critical to the long-term sustainability of the nation’s communities and ecosystems.1
New products and systems are being developed to handle both incoming and wastewater processing. By having such a unit installed and collecting waste before it goes to a wastewater treatment plant, there’s a substantial savings to the municipality regarding energy used in processing. This product is available for home and industrial/commercial use and provides multiple benefits by reducing the amount of wet waste and grease flowing down drainage systems.
Among the product’s attributes, it:
- Significantly reduces operating costs by reducing the frequency and associated costs of grease trap maintenance;
- Prevents clogging and reduces maintenance of drainage systems and grease traps;
- Reduces the cost to municipalities for treating sewage at treatment plants;
- Meets wastewater discharge regulatory compliance standards;
- Reduces odors created by grease traps;
- Minimizes the need for costly enzymes and bacteria treatments; and
- Reduces the amount of airborne bacteria released when cleaning a grease trap.
This waste interception system “would have significant benefits in reducing BOD/SS/grease loadings from food-related operations and, as a result, assist those operations in meeting (Toronto) Sewer Use Bylaw 457-2000 limitations for those pollutants,” according to V. Lim, P.E., manager of Toronto’s Industrial Waste and Stormwater Quality division. He added, “In a report by Toronto Works & Emergency Services (see Figure 1), we have determined that, on average, the device is capable of removing 50 percent of suspended solids (SS) and 40 percent of biochemical oxygen demand (BOD) from food waste streams.”2
Mission of emissions
In the mid-’90s, the food processing industry faced increased environmental and effluent emissions restrictions. Companies like Del Monte Foods funded and conducted research and testing on using semi-permeable membranes to remove organic components from wastewater. Straining solids at the source made sense and helped companies meet the new restrictions and conserve water as well.3
An expansion of the particle straining system takes another step further and uses wastewater digesters to process these residuals to an anaerobic digester that’s converted into biogas and biosolids. Biogas produced from wastewater sludges is compressed and transported via a pipeline to a power station to generate energy.4 The Los Angeles Department of Public Works received the award for “Top Ten Public Works Projects of the Century” from the American Public Works Association for its Hyperion Treatment Plant project that uses this technology in an effort to protect residents, tourists and neighbors of the world-renowned Santa Monica Bay from wastewater pollution (see http://www.lacity.org/SAN/htptop10/htp.htm).
“We are designing, constructing and operating new and expanded water and wastewater treatment plants through our Integrated Resources Plan over the next two decades,” notes Ellen Stein, L.A. Public Works board president. “We are building additional capacity into existing sewage collection systems as well. The planning process aims to ensure that environmental impacts on affected communities are kept to a minimum.”
Stein adds, “While the new millennium heralds promise of continued regional economic prosperity, concerns exist about the city’s water supply and its ability to collect, treat and recycle an ever-growing volume of sewage and sewage biosolids. Our planning efforts have assembled a diverse community to identify, discuss and formulate policies for the city’s social, economic and demographic well-being through 2020.”
Another way to preserve the quality of water and minimize damage to plumbing systems is through reducing the delivery of hazardous waste materials to plumbing systems. Cleansers and other caustic agents are poisoning waters and eroding plumbing systems. In “Guide to Hazardous Products Around the Home,” one chapter is devoted to safer alternatives for handling a variety of cleaning situations that lessen exposure to toxins in the air and/or water.5 Using more environment-friendly cleaning agents, and straining wet waste solids at the source, reduces the processing time in municipal water treatment plants and preserves water.
Where once facilities were being built simply to process more water, the higher costs of that new water infrastructure make lower costs of improving water-use efficiency and productivity a more practical investment.6 Better sprinkler systems, more efficient water treatment methods in homes, restaurants, hotels, existing municipalities and other businesses can all combine to make the plumbing industry a player in the water conservation game.
Maintaining sound plumbing systems is key as well. The environmental impacts from corroded metal in deteriorating plumbing systems introduces contaminants into drinking water systems, causes water loss and can leak and damage property. A study under way by Marc Edwards, recipient of the National Science Foundation Presidential Fellowship for his work in environmental engineering, is drinking water corrosion. This requires expertise in materials, water chemistry and microbiology. As an engineer, Edwards is attempting to merge science with technology to help water utilities, plumbers, homeowners and pipe manufacturers obtain practical solutions to this costly problem.7
Conservation of water must be, in part, voluntary because of our nation’s lack of a basic national water policy. Future generations might be affected as aquatic systems are destroyed and the world’s food supply is threatened.8 Along with the simple act of one person not littering, individuals can make a difference by installing more environment-friendly plumbing systems and being conscious of what they send down the pipes.
Effluent treatment systems are designed to either break down solid matter and make the wastewater suitable to be discharged directly into a river without upsetting the ecosystem, or sent to a sewer with a lower pollution content for treatment by the facility prior to channeling to a river.9
New systems, methods and devices are gaining popularity to keep up with the trend toward conservation and protection of our waters. The plumbing industry is doing its part by staying abreast of developments and options and advising clients on how they can make a difference in water conservation.
- Hirsch, Robert M., Timothy L. Miller and Pixie A. Hamilton, “Using Today’s Science to Plan for Tomorrow’s Water Policies,” Environment, January/February 2001.
- Shaw, Martin, “Report – Assessment of Rhino Wet Waste Interceptor 1047.20GEN,” Toronto Works & Emergency Services, February 2001.
- “Membrane Filtering Saves Water for Food Processing Industry,” Journal of Environmental Health, Volume 56, Issue 1, July/August 1993.
- Haug, R. Tim, et al., “Using Wastewater Digesters to Recycle Food Residuals Into Energy,” BioCycle, September 2000.
- “Safer Alternatives: Reducing the Risk,” Guide to Hazardous Products Around the Home, courtesy of Missouri’s Household Hazardous Waste Project.
- Gleick, Peter H., “Water: Threats and Challenges Facing the United States,” Environment, March 2001.
- “Metallic Plumbing Producing Environmental Problems,” Industrial Environment, Volume 11, Issue 3, March 2000.
- Gleick, Peter H., “Water: Threats and Challenges Facing the United States,” Environment, March 2001.
- Atkinson, Bill, “Clean up the Waste Waters,” Food Manufacture, Volume 73, Issue 4, April 1998.
About the author
Mark Wiertzema is president and CEO of Rhino Ecosystems, of Woodbridge, Ontario, Canada. He has 25 years of experience in corporate financial and strategic management and an extensive managerial background in environmental solutions at the municipal level. Rhino Ecosystems manufactures the Wet Waste Interceptor®, which is described in this article. He can be reached at (877) 746-6224, (905) 264-0198 or website: http://www.rhinoeco.com.
Figure 1. Evaluating a Waste Reduction System
The following is an evaluation of the waste interception system discussed in this article by the City of Toronto, Canada:
Sources of Waste:
Location 1: Potato/carrot peeling operation final waste stream.
Location 2: Pasta making operation sink waste.
Location 3: Dishwasher waste from large downtown hotel.
Grab samples were taken before and after filtration through the unit at approximately the same time. Sample size was 1 liter. Sample containers were glass jars. Samples were analyzed at the Toronto Works and Emergency Services laboratory at 30 Dee Ave., Weston.
Influent and effluent samples were analyzed for biochemical oxygen demand (BOD) and suspended solids (SS) as per Standard Methods for the Examination of Water & Wastewater.
SS Removal BOD Removal Effluent SS Effluent BOD
Location 1: error 64% 22,500 mg/L 1990 mg/L
Location 2: 45% 15% 324 mg/L 1000 mg/L
Location 3: 54% 33% 423 mg/L 450 mg/L
This device accomplishes solids removal via physical filtering and straining of waste solids and removes BOD associated with those solids. Solids removal efficiency depends on particle size, effective size of the openings in the “sock” membrane and consistency of the solid particles. As such, removal efficiency is expected to be somewhat variable depending on the nature of the waste. It would be important to monitor this system to ensure the membrane doesn’t fill to capacity in order to avoid failure or rupture of the membrane.
The device has significant benefit in reducing SS and BOD discharged from domestic or commercial operations involving food-type wastes. Hence it would be of benefit in meeting City of Toronto sewer use bylaw limits.
In the case of restaurants, when placed upstream of the grease trap, this device would have the advantage of reducing solids loading to the grease trap. Vegetable matter can reportedly comprise 50% of the waste in a grease trap. This would increase grease trap capacity and reduce loading of animal grease to sewer systems, which is a frequent source of plugging and maintenance required by City staff. Loading of BOD and grease to sewage treatment plants would similarly be reduced. This device will assist restaurants in meeting sewer bylaw limits for BOD and suspended solids (300 mg/L and 350 mg/L respectively) by removing particulate food waste. It would appear that the filter alone wouldn’t be sufficient in all cases but would be part of a strategy to meet bylaw limits in connection with a properly sized grease trap. Finally, because solids are retained separately, the opportunity for composting of solids is made possible by transferring retained waste to the nearest compost facility.
It’s noted that the system appears to be suited for either domestic or commercial application. We would recommend that the company explore the utility of using the filter in connection with garbage-grinding devices for recovery of the solid fraction of ground municipal waste or commercial waste.
Commercial/industrial waste grinding devices are currently illegal in Toronto if connected directly or indirectly to a sewer. There may be an interest, however, in re-evaluating this restriction if the solid fraction could be removed prior to sewer discharge. There may also be some value in determining effectiveness of the unit in connection with domestic sink “garburetors” that don’t meet Toronto bylaw requirements on particle size. It would also be interesting to determine how the unit performs in connection with domestic sink garburetors that conform with the Toronto bylaw.
Martin Shaw, Senior Engineer, Industrial Waste Control Department, City of Toronto