Spray and Drip Irrigation for Wastewater Reuse, Disposal
Total Page：16
File Type：pdf, Size：1020Kb
Winter 1999 Vol. 10, No. 1 SMALL L F A L N O O W I T S A N C L E E A S R U I N G H O PipelineSmall Community Wastewater Issues Explained to the Public SPRAY AND DRIP IRRIGATION FOR WASTEWATER REUSE, DISPOSAL id you ever wonder how golf Another benefit of applying wastewater courses keep their large fair to land is that the soil provides additional Treated wastewater can ways looking so lush, healthy, treatment through naturally occuring be reused to irrigate . D and green all season long? physical, biological, and chemical pro The answer may surprise you. cesses. Irrigating with wastewater also In many communities in the U.S. and adds nutrients and minerals to soil that are • lawns; around the world, treated wastewater is good for plants, and it helps to recharge • parks; reused to irrigate golf courses, lawns, valuable groundwater resources. • landscaped areas around offices landscaping, forests, and even crops. and industrial developments; Because water is such a precious com • landscaped areas around modity, recycling wastewater can have A Solution for “Problem” Sites residences; both economic and environmental benefits Irrigation systems often can be used in for communities. Irrigation also can be place of soil absorption fields (drainfields) • pasture grass; the most practical and environmentally to provide final treatment and disposal • highway medians; friendly way communities can dispose of of wastewater from individual onsite • golf courses; treated effluent from wastewater treatment sys tems, such as septic systems and home plants and individual home systems. aerobic treatment units. As the demand • cemeteries; for land in rural areas is increasing, more • forests; Better for the Environment sites are being developed in places previ • trees, corn, alfalfa, and other feed, Currently, the most common way com ously considered unsuitable for onsite fodder, and fiber crops; and munity treatment plants dispose of waste systems. Irrigation sometimes is permitted • food crops. water after treatment is to discharge it to as an alternative wastewater disposal surface waters. However, as populations method for difficult sites, such as areas grow, the burden to local streams and with slowly permeable soils, shallow rivers is increasing. Reusing wastewater soils, or complex topographies. when they may be a good option for to irrigate land can help protect precious This Pipeline issue provides a brief homes, businesses, and communities. surface water resources by preventing overview of two types of wastewater Operation and maintenance issues also are pol lution and by conserving potable water irrigation systems—spray systems and discussed. for other uses. sub surface drip systems—how they work, Readers are encouraged to reprint Pipeline articles in local newspapers or include them in flyers, newsletters, or educational presentations. SPRAY & DRIP IRRIGATION Is irrigating with wastewater a good option for your home or community? If you live in an area where water must is higher quality than the wastewater system clogging. Additional treatment be conserved or is expensive, or where discharged from treatment plants due to may be necessary to protect the receiving other options for disposing of wastewater the additional treatment provided in the soil. environment and may include secondary are restricted, then reusing wastewater for Regulations protect public health and treatment plus disinfection. This adds to irrigation may be a good option for your the environment by requiring that waste water the cost of building, operating, and main home, farm, business, or community. It also always be pretreated prior to irrigation and taining systems, which should be consid can be a good choice simply because it is an by restricting its quality, use, and the manner ered when determining whether irrigation efficient use of local resources. and location of its application. Cumulative is a practical wastewater disposal option. In arid climates, such as in Arizona, New levels of nutrients, salts, heavy metals, and Mexico, and parts of California, for exam diseasecausing organisms also must be Site Conditions Are Important ple, or where the demand for water threat ens monitored in the soil at some sites. Not all sites are appropriate for waste to exceed the supply, as it does in parts of water application. Communities wishing Florida, many homes and businesses could Regulations Vary to dispose of wastewater from treatment not afford to maintain grass lawns Wastewater reuse is not permitted every plants through irrigation sometimes must or landscaped areas without reusing waste where. Regulations vary from state to state purchase or lease suitable land for dispos al water. In Hawaii, treated wastewater is used and sometimes from community to commu or enter into cooperative arrangements to irrigate pineapples and sugar cane to save nity. State and local governments may have with local farmers or landowners. Sites money and conserve fresh water for other additional or more stringent requirements near surface water or high groundwater uses. than the federal regulations. often are restricted, especially when Irrigation also can serve as an alternative Community residents can contact local these are used as drinking water sources. onsite disposal method for lots deemed health agency officials to find out about Regulations typically require minimum unsuitable for conventional septic tank/ regulations in their area. separation distances or buffer zones from soil absorption systems. Because irrigation ground and surface water resources and sys tems are designed to deliver wastewater Pretreatment Is Required public areas to minimize contact with slowly at rates beneficial to vegetation, and After wastewater receives primary and wastewater. because the wastewater is applied either sometimes secondary treatment in a com Other important site selection criteria to the ground surface or at shallow depths, munity treatment plant or individual onsite include the type of soil, soil wetness, irrigation may be permitted on certain sites treatment system, additional treatment steps slope, drainage patterns, and local cli mate, with high bedrock, high groundwater, or often are required prior to irrigation to including rainfall amounts and evaporation slowly permeable soils. Irrigation systems reduce the amount of suspended solids and rates. In areas that have cold or wet also can be designed to accommodate sites organisms in the wastewater. Both can pose weather part of the year, waste water often with complex terrains. a threat to public health and clog systems. must be stored in lagoons or holding tanks Local governments sometimes choose Microorganisms, such as bacteria, can col until irrigation is needed. Some irrigation to reuse wastewater from community lect or multiply and create slime that clogs equipment also can freeze in very cold treatment plants for irrigation, rather than systems. Pretreatment also minimizes odors weather. discharging all of it to local surface waters. in wastewater, so there is less potential for Irrigation can help communities to save creating a public nuisance and attracting Maintenance Is Necessary money or avoid exceeding surface dis charge animals that can spread diseases. All systems, including irrigation sys permit limits, while preserving Different degrees of pretreatment are tems, have operation and maintenance the quality of local water resources for required for the wastewater depending on requirements. These include periodic drinking water, aquatic life, and recreation. how it will be used and the intended method checking and cleaning of filters, checking Some communities even have two sep arate of irrigation. For example, standards are more valves, pumps, and timers, and, in some distribution systems—one for rigorous for surface irrigation methods, such cases, monitoring wastewater quality and potable water and another for reclaimed as spray irrigation, and when irrigating food its impact on soils. Large systems serving water for watering lawns and other irrigation or feed crops or land intended for public use. farms, businesses, or communities often needs. Biological pretreatment to remove organic have operators, but most systems are at matter from the wastewater is fol lowed by least partially automated. Is it safe? filtration, to remove small particles from the Although spray and subsurface drip Irrigating with wastewater is safe when all wastewater, and disinfection. irrigation systems serving individual federal, state, and local regulations regarding Subsurface drip irrigation systems also homes may only need maintenance about its treatment and use are strictly followed. employ filters mainly to protect against once or twice per year, homeowners should When regulatory requirements are met, the consider that these systems will require wastewater returned to the more attention than conventional onsite environment after irrigation usually systems. 2 PIPELINE - Winter 1999; Vol.10, No. 1 SPRAY & DRIP IRRIGATION Spray Systems Irrigate Laws, Parks, Crops 1 House Sewer 3 Septic Tank 5 Sand Filter 7 Pump Chamber Example 2 Septic Tank 4 Dosing Tank 6 Cl2 Disinfection 8 Spray System residential spray system 1 schematic 8 2 3 4 5 6 7 Spray irrigation is an efficient way to Chlorination is the most common disin Another design used to irrigate row nourish plants and apply reclaimed waste fection method used with spray irrigation. crops, called a portable irrigation reel, is water to land. Some spray systems are