Wastewater Processing and Water Conservation 1
Running head: Wastewater Processing and Water Conservation Practices in Florida
Wastewater Processing and Water Conservation Practices in Florida
Jake Emerson
University Of Florida
Abstract
The sustainable use of water has become quite a concern for all professionals within the building construction and construction design industry. Our lack of water conservation practices in the United States and the steady increase in worldwide population has led to a deficiency of water supply to the expected future demand. In an effort to efficiently utilize our water resources, architects have made design innovations and construction professionals have utilized new construction techniques. Some of the most popular practices used today are water harvesting, and the reuse of greywater. Water from the bath, shower, washing machine, and bathroom sink are the sources of greywater that can effectively be recycled for other uses. The ways in which these two water conservation practices are used in construction is limitless, but the benefit from the sustainable use of finite water resources is necessary for future demand. The state of Florida could potentially be a perfect candidate for these types of green practices due to its climate and need for sustainable water supply/use techniques. The reuse of greywater has many applications and has long strides to make in the future. Greywater treatment and reuse will hold many innovative techniques and practices that professionals are developing every day.
Wastewater Processing and Water Conservation Practices in Florida
“Despite the common belief that Florida has an overabundance of freshwater for human use, in reality Florida has similar water shortage problems as do many other states” (Plant Management in Florida Waters, 2004). Florida has a large population and due to its beautiful coastline and comfortable climate, the population is exponentially growing every year. The state of Florida is divided into five subdivisions of populations that consume water. Some of the divisions do not have any problems supplying the current demand, and there are other divisions that do not have enough water to supply the population. These water deficient divisions are requesting more of the finite resource to supply the growing demand when they did not have enough water to supply the population they started with. It is not just the population growth that is a cause for concern, there is also data that supports that the individual citizens of Florida consume a great deal of water. Floridians use more water per capita than residents of any other state except California (Plant Management in Florida Waters, 2004). The fresh water is used for many different purposes in Florida including: agriculture, industrial, recreational irrigation, domestic lawn irrigation, municipal, and power generation. Agriculture in Florida is the largest consumer of fresh water due to the required water for proper irrigation. These consumption issues must be resolved by Florida and its citizens to ensure that we find a sustainable balance of our finite water resources. Some of the most promising methods of water conservation are the reuse of greywater and water harvesting. These two methods are already in use in many different countries including the United States. This report will explain the two methods in their application to Florida as well as some of the examples that are already in progress.
Using water harvesting as a way to conserve water is not a new technique. In fact, the practice of rainwater harvesting or the catchment and distribution of rainwater is hundreds of years old. The reason why this can be such a beneficial technique for Florida is because the state receives an average of 54 inches of rainfall per year (Plant Management in Florida Waters, 2004). A rainwater harvesting system is typically composed of the following components: catchment, conveyance system, filtration, storage, and distribution. The catchment is the area by which the rainwater falls and eventually collected by. In Florida, a catchment surface would typically be metal, clay, and cementitious materials however; other materials such as asphalt shingles can be used with proper filtration systems (Sustainable Building Sourcebook, 2005). A conveyance system is the means by which water is transported to the rainwater storage unit. A gutter system and possibly conveyance piping are the most popular conveyance systems in Florida. The gutter system optimizes gravity as a propulsion system for the rainwater with the application of a slope upon gutter installment. The gutter is eventually connected to a downspout that takes the rainwater to either conveyance piping or the storage system. The rainwater is stored in a cistern that can be installed above or below ground. To optimize the performance a cistern, the storage unit should be composed of concrete, steel, ferro-cement, or fiberglass (Sustainable Building Sourcebook, 2005). The cistern type is dependent upon whether its intended use is for potable or non-potable water. Because the catchment surface is exposed to outside elements that may cause contamination, a filtering system is required to separate the water from potential debris. A filter can be placed over the gutter system for this process but if the rainwater is intended to be a source of potable water the use of a roof washer is suggested. “The primary function of the roof washer is to isolate and discard the first water that has fallen on the roof after rain has begun and then direct the rest of the water to the cistern. Ten gallons of rainfall per thousand square feet of roof area is considered an acceptable amount for washing” (Sustainable Building Sourcebook, 2005). The final component to the water harvesting system is the distribution system, which can be via gravity or a pumping system depending upon the installation location of the cistern. If the water is intended to be used as potable water, an additional purification system is required. These are all important to consider when applying these systems and their role in Florida’s water conservation effort because each component affects the life cycle cost of the system.
Greywater is water that has been used by washing machines, sinks, dishwashers, and bath use. Greywater is not to be confused with blackwater, which is water that has been used for human waste. Greywater and its application towards water conservation does not have the historical roots of water harvesting, however; the technique is gaining in popularity at a rapid pace. On average, the US household will consume 74 gallons of water for indoor use (American Water Works Association, 2005). An average of 42.5 gallons of the 74 gallons is greywater that can be recycled for other uses (American Water Works Association, 2005). Greywater is typically recycled for use in toilets, and landscape irrigation. American households use an average of up to 70% of their water use per capita to irrigate domestic gardens and lawns (American Water Works Association, 2005). This does not even include the countless gallons of water that Florida’s thriving agriculture industry uses to irrigate crops. Though greywater recycling has many benefits, the potential use in irrigation alone could have a huge effect on Florida’s water conservation effort. “The benefits of grey water recycling include: lower fresh water use, less strain on failing septic tanks or treatment plants, grey water treatment in topsoil is highly effective, ability to build in areas unsuitable for conventional treatment, less energy and chemical use, groundwater recharge, plant growth, and reclamation of otherwise wasted nutrients” (Oasis Design, 2005).
There are many methods that Florida could use to treat greywater for recycled use. One method that uses biological treatment with a rotating biological contactor (RBC) is very effective (Freewater UK Ltd., 2004). After the RBC stage has completed, the disinfection of greywater is by means of UV radiation (Oasis Design, 2005). Some other systems use natural methods with plants, snails, and other natural means to treat the water before reuse. Countries like Germany are currently experimenting with greywater purification plants for mass production. In Canada, a housing project system will be capable of treating gray water from sinks, laundry, and showers for reuse in showers, laundry, and toilets (Oasis Design, 2005). Processes like this where humans come in direct contact with the water are still in the experimental phase due to possible health issues.
Some of the barriers affecting the approval of greywater reuse are mainly due to the soil type and safety. The texture, structure, and the slope of the soil that will utilize the recycled greywater all affect the ability to use the technique. Another problem is that greywater is a perfect carrying system for harmful bacteria like Ecoli. There are many states in the US that have not legally approved the practice of greywater recycling for irrigation. The scope of use and standards of greywater and wastewater reuse are outlined in Chapter 62-610, Florida Administrative Code, and Title XXIX, Public Health Chapter 381.0065 of the Florida statutes (Florida Department of Environmental Protection, 2005). Although these policies mainly address reclaimed water, it is the only legal restriction close to greywater that Florida has. The laws set forth by the state of Arizona on greywater are arguably the most inclusive and beneficial way to promote and regulate the process. Arizona uses a three tiered system based on quantity used that includes, R18-9-711 (systems under 400gpd), R18-9-719 (systems 400 to 3000 gpd), and R18-9-101 (systems over 3000gpd) (Oasis Design, 2005). These laws require the permitting of the use of greywater as a means of irrigation as well as a government published booklet on greywater and its safe use. This might be a format that the National Legislative and Regulatory Committee might emulate in the future to promote the legal use of greywater in Florida’s future (Water Reuse for Florida, 2003).
One of the biggest barriers of the adoption of these two methods is the initial cost of the system components. A consumer must be able to value the water supply enough to purchase the extra equipment that is necessary to operate one of these efficient systems. The typical cost of water is so low that it takes a relatively long time to make up the cost of the efficient components. The potential of water increasing in price due to the law of supply and demand, or as a method of inducing conservation might be in the near future. Martin and Kulakowski from the EPA recently stated, “Information and education promoting conservation do not appear to be effective by themselves in achieving a conservation goal without at the same time imposing significant price increases to provide a financial incentive to conserve water” (U.S. Environmental Protection Agency, 2003).
There are already examples of these water conservation techniques in Florida. One of the most popular residential examples is the house provided by The Florida House Learning Center. This house is located in Sarasota and among its water conserving features is a greywater and water harvesting system. The water harvesting system utilizes 2-2,500 gallon tanks, 3,900 square feet of catchment surface, and a system of pumps to allocate the water (Pushard, 2004). A major component to the greywater system is a kitchen filtration system to cleanse the water of unwanted debris and sediment (Pushard, 2004). This project, designed for public education, has had thousands of visitors since its doors opened in 1994. “The Average water per capita use in Florida has been reduced by almost 40% - from 140 (530 liters) to 88 gallons (333 liters) per day, in the years since the Florida House opened (Pushard, 2004).
In non-residential construction, these methods are also prevalent. Florida Universities are adopting water harvesting building techniques. University of Florida uses the technique to obtain LEED certification on new buildings, and the University of South Florida uses water harvesting as a component to green roof systems. Though Florida is showing an interest in the adoption of these water conservation techniques there are a few benchmark examples of water harvesting.
In Melbourne, Australia, a zero water use commercial building, the 60L, has been constructed. The building uses rainwater as a supply for every type of consumption with the exception of the fire sprinklers. “The rain is collected from the roof, stored in two tanks on the ground floor, filtered, and then sterilized prior to use by tenants in taps and showers” (Pushard, 2005). “More than 132,000 gallons (500 kiloliters) of rainwater can be collected in an average year” (Pushard, 2005). The 60L also contains a greywater recycling system to optimize the tenant’s use of water. The used water from the tenants is fed into a biological treatment system and is then used again as toilet water, irrigation for the roof garden, and use in the water feature of the building. One of the most amazing things about this project compared to Florida is that Australia only receives and average of 25.8 inches of rain per year compared to Florida’s 54 inches. This example illustrates how effective these methods could be if utilized in Florida.
The final, and most innovative method of using a greywater technique, is the Living Machine in Oberlin, Ohio. “The Living Machine® treats wastewater using a system of engineered ecologies that include microbes, plants, snails and insects, and is designed to treat up to 2,000 gallons of the building's wastewater daily in a beautiful, garden-like atmosphere”(Janas, 2000). The greywater and blackwater combined go through a system of native plants and different bioreactors before receiving a final Ultraviolet disinfection treatment so that the water can be used again in the 13,600 square foot facility. This is an important example because it can be inexpensively applied to greywater systems in Florida, thus making the cost benefit that much more attractive.