Water: Reduce, Reuse, Recycle
In certain parts of the world, communities’ sole source of water is water from deep wells, often many thousands of feet down. Almost half of the United States drinking water is groundwater. The Ogallala Aquifer is the sole source of water in central western part of the United States. An estimated 12 billion cubic meters of water is removed from the Ogallala Aquifer each year and 6 percent of the aquifer will dry up every 25 years, which leaves the residents and farmers of the Great Plains unsure about how long their water supply will last.
Water from groundwater sources is usually free of chemical and microbial contamination, but often become contaminated by disposal of liquid waste, mining operations, and agricultural runoff. By providing protection to the source, either through buffers from the reservoirs or by protecting the wellhead for the deep wells, water is available without much treatment.
There are less uncontaminated water supplies available due to increasing population and increased use of water. Water is treated before human consumption. Disinfection is an important step in the water treatment process to destroy pathogenic bacteria and other harmful agents. Most water is treated with chlorine, which is a very effective and economical method of treatment. An important advantage of using chlorine is that it has residual properties and continues to provide germ killing potential as the water travels from the distribution point to the end users. There are concerns about the formation of disinfection by-products from the reaction of the chlorine with humic substances in the water. Some of the bacteria and viruses we want to treat are becoming resistant to traditional means of disinfection.
Sanitation and Water Pollution
Sanitation is directly related to water quality and water pollution. The accepted approach to sanitation in the last century is to collect liquid waste in sewer systems, treat the wastewater in centralized treatment plants, and then discharging the effluent to surface water bodies. Although conventional sewer systems have significantly improved the public health situation for the communities, continued use adds pollution to our water supplies and reduces the purity of water needed for potable application later. This is becoming a worldwide problem not only for developing world with its inadequate sanitation, but also for developed world with its aging infrastructures that cannot meet the needs of increasing population.
The conventional sewer system was developed at a time, in regions, and under environmental conditions that made it an appropriate solution for removing liquid wastes from cities.
Today, some conventional sewer systems are no longer able to meet the pressing global needs. We need to develop newer ideas to address the issues of water quality conservation along with better means of waste disposal that do not pollute our water sources.
Water-based sanitation systems are not only a serious disadvantage in water reuse, but also have become a liability to human health. Lack of nutrient recovery leads to a linear flow of nutrients from agriculture, via humans, to recipient water supply. The valuable nutrients and trace elements contained in human excrement are rarely rechanneled back into agriculture in conventional systems. Only a small fraction of the nutrients contained in the sewage sludge are reintroduced into the soil as fertilizer. Most of the nutrients are either destroyed in the treatment process (e.g., by nitrogen elimination) or enter the water cycle where they pollute the environment and increase unwanted algae in lakes and rivers.
Not returning the nutrients to the soil has led to an increasing demand for chemical fertilizers, in response to the problem of decreasing soil fertility. Chemical fertilizers require large amounts of the energy and mineral resources such as phosphorous. Farmers around the world yearly require 135 million tons of mineral fertilizer for their crops, while at the same time conventional sanitation dumps 50 million tons of fertilizer equivalents into our water.
Sanitation and the Future
Our conventional drinking and wastewater systems are largely linear, end-of-pipe systems where drinking water is misused to transport waste into the water cycle, which causes environmental damage and hygienic hazards and contributing to the water crisis. As population increases, the demand for water increases, which increases pollution and further depletes the available water. Some wastewater treatment plant s overflow into waterways thereby reducing the amount of clean water. The new technologies that require chemically treated, high-pressure water to produce natural gas promise to further increase the stress on our water supplies. As the availability of clean, potable water and improved ways to manage our waste will become all-important.
Alternative Waste Management
Older cities have sewer systems that combine waste and storm water in the same pipe. When rainstorms occur, it overwhelm the retention capacity of the sewage treatment plant, the combined storm water and sewage overflow into local rivers or streams.
Solutions to wastewater problems in urban areas have been applied to rural communities. Federal programs that provide grants for construction of wastewater facilities, sewers and centralized treatment plants were constructed in these low-density rural settings. The cost of operating and maintaining the facilities imposes severe economic burdens on the communities.
Wastewater treatment and disposal systems serving single homes have been used for many years, they have often been considered an inadequate or temporary solution until sewers could be constructed. Research has demonstrated that such systems, if constructed and maintained properly can provide a reliable and efficient mean of wastewater treatment and disposal at relatively low cost.
The methods proposed to manage excreta and chemical waste in ways that serve to protect the water supply, and reduce the causes of disease. They also serve to address waste management at the source in an environmentally efficient manner without polluting the watershed. Possible alternative sources include:
- Aquatic plants
- Constructed wetlands
- Biological filters
- On-site blackwater systems
- Septic fields
- Latrines and privies
- Composting toilets
The alternative sources of water and waste disposal need to be implemented to preserve our water quality and the nutrients in our wastewater will be reused efficiently.
Bob Boulware is President of Design-Aire Engineering, Inc. Bob is a past president of the American Rainwater Catchment Systems Association (ARCSA) and an Accredited Rainwater Systems Design Professional. He is a 30+-year member of ASHRAE and past president of the Central Indiana Chapter of American Society of Plumbing Engineers (ASPE) and serves on the ASPE National Standards Committee. Mr. Boulware is a member of the International Association of Plumbing and Mechanical Officials (IAPMO) Alternative Water Sources Committee, and helped to develop the Green Plumbing Supplement to the upcoming editions of the Uniform and the International Plumbing Codes. Mr. Boulware has taught Environmental Design for mechanical and electrical systems at Ball State University and plumbing design at IUPUI. Follow us @daengineering on Twitter & www.daengineering.com. Bob can be reached at firstname.lastname@example.org.
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