Module 3.1 Pollution Prevention

Transcription

1 Module 3.1 Pollution Prevention Conservation of Water and Prevention of Water Pollution from Point Sources Conservation of Water and Prevention of Water Pollution from Point Sources Pollution prevention for water includes: conservation of the use of water resources and reduction of pollution in surface and groundwater Reducing pollution to water involves considering: point sources nonpoint sources Module 3.1 will consider conservation of water resources and point sources of pollution Module 3.2 will consider nonpoint sources of pollution Conservation of Water Resources Conservation of water resources is an important aspect of pollution prevention because reducing the amount of natural resources that are used should always be an important part of P2 programs Conservation of resource use reduces pollution overall since any water use involves an expenditure of energy and mobilization of technology, all of which adds to the total pollution load Point and Nonpoint Sources A point source is a location with an identifiable point of discharge to a water body Point sources include: industrial facilities sewage treatment plants Nonpoint sources are without an identifiable point of discharge Nonpoint sources include: farms suburbs golf courses urban areas 1

2 Regulation of Point Sources Discharge of pollutants to water is regulated under: The Clean Water Act (CWA) of 1972 Amended by the Water Quality Act of 1987 Strengthened by the Safe Drinking Water Act The CWA includes the National Pollutant Discharge Elimination System (NPDES) permitting process Regulation of Point Sources Point sources that discharge pollutants to surface water must have a NPDES permit that specifies the type and concentrations of contaminants in the discharge streams Point sources must sample and test their effluent regularly and provide the results of those tests to the state and EPA When permits expire, new levels are negotiated and an attempt is made to decrease allowable discharge limits Regulation of Point Sources As I mentioned, some of the facilities that must treat and dispose of the largest quantities of waste water are the sewage treatment plants of towns and cities. These are also called municipal wastewater treatment facilities or Publicly Owned Treatment Works (POTWs) Even though they are publicly owned and operated by local government, they are closely regulated and must have their own NPDES permits The Pollution Prevention Hierarchy As always, the pollution prevention hierarchy gives a rank ordered list of activities from most desirable to least: Reduce at the source Reuse whenever possible Recycle Treat Dispose 2

3 The Pollution Prevention Hierarchy The wastewater stream has two characteristics: Volume Pollutant load Generally, the activities that reduce water use will also reduce the volume of the wastewater stream so those are tied together Some activities might not reduce the volume of the wastewater stream but will reduce the concentration of the pollutant loads Reduce Wastewater Stream at the Source Examples of source reduction activities in industry include: Shift from aqueous production methods to dry to eliminate wastewater streams Implement a closed loop for heating/cooling rather than a flow-through system Change from water cooled systems to air cooled Control leaks and spills of water Control leaks and spills of chemicals that might contaminate a clean water stream Of these, the first four reduce both quantity of water used and pollutant load. The last reduces only pollutant load. Reduce Wastewater Stream at the Source Examples of source reduction activities for POTWs include: Install low flow shower and toilet fixtures in homes and businesses Encourage conservation of water use to decrease flow to the POTW Control the type and quantity of pollutants that are poured down drains and flushed down toilets Educate businesses and public about proper disposal methods for waste Separate storm water runoff systems from sewer systems and treat wastewater streams separately Of these, the first two concentrate on reducing water use. The last two concentrate on reducing pollutant load. Reuse of Wastewater In a production process, often water can be captured, cleaned, and returned to the system As it becomes dirty, some wastewater will have to be removed and new water added Applications include water used for: Heating and cooling Cleaning Flushing process debris Obviously, reuse of water conserves that resource 3

4 Recycling of Wastewater Wastewater may have uses outside of the process (municipal or industrial) that created it If the wastewater contains excess nutrients (nitrogen and phosphorus), it may be useful for fertilization. Even if it doesn t, it is useful for irrigation. Agricultural fields Golf courses Government owned lands Recycling of Wastewater Increasingly, in arid areas like the Western U.S., discharges from POTWs are being considered for recycling to drinking water Obviously, health issues require rigorous testing and treatment to ensure all pathogens are destroyed Recycling of wastewater can be a key resource conservation measure in arid areas Treatment of Wastewater Treatment of wastewater occurs at both POTWs and at industrial sites Steps in the treatment process include: Screening to remove debris Primary treatment Settling out solid material Secondary treatment Biological treatment to remove nutrients Treatment of Wastewater Tertiary treatment (not often used) Removes remaining nutrients Disinfection Chlorination is most common. Also ozone treatment and UV are used but are more expensive. Chlorine byproducts must be removed prior to release. 4

5 Disposal of Wastewater Once the wastewater streams have been properly treated, release to surface or ground is easy and safe The key to this is proper collection, treatment, and ongoing testing and monitoring to ensure that the water being disposed is clean To implement a program: Research the pollutant loads Permits should specify contaminants and maximum levels allowed Test records should characterize actual contaminants and levels (often well below permit levels) Research the amount of water used historically Records on quantities if water is metered Carry out calculations for amounts generated by sinks, toilets, showers, Tie the contaminants and quantities to the various sources Tie the amount of water used to the various types of uses Toilets Sinks Showers Lawn watering Cafeteria Laundry Stay as high on the hierarchy as possible One issue with water use is that it is generally free or inexpensive Many cities in the west do not even meter water While this is nice for homeowners, it discourages conservation 5

6 Identify opportunities Involve everyone affected Calculate economic payback periods Publicize success Keep good records 6