Presentation on theme: "Septic systems 1. Septic tanks with drain fields. P.465 A. Wastewater is drained into a septic tank. Grease & oil rise to the top & solids settle to."— Presentation transcript:
1. Septic tanks with drain fields. P.465 A. Wastewater is drained into a septic tank. Grease & oil rise to the top & solids settle to the bottom where they are decomposed by bacteria. B. The clarified effluent is channeled out through a drain field of small-perforated C. Pipes just below the surface of the soil. The aeration rate is high so that pathogens are killed & soil microorganisms can metabolize any nutrients carried by the water. Excess water percolates up through the gravel & evaporates. The tank is pumped out into a tank truck & land filled.
Individual action Pump your septic tank every 2-5 years depending on household and tank size. Install water-saving devices and reduce water usage in the home. Do not use septic system additives, garbage disposal, or harsh drain cleaners. Protect the drainfield area from damage by vehicles, heavy animals, or construction. Repair or upgrade your system if a need is indicated by inspection. Community Action Establish permit and inspection requirements to ensure proper installation. Educate the public about septic system care. Ban hazardous additives or cleaners for septic systems. Connect homes and businesses to central sewers when feasible. Require additional treatment, such as a sand filter, when needed. Establish ample minimum lot sizes for septic systems. Train and certify septic system professionals.
1. Effluent sewerage. A hybrid between septic tank & full sewer. A. A small tank collects & digests solid waste & effluents are pumped to a central treatment system. B. This eliminates the need for drain fields where space is critical. Tanks are emptied once a year.
1. Municipal Sewage Treatment. A. Primary treatment. To remove solids. A screen separates large solids from the waste stream followed by a quick settling tank. B. Secondary treatment. Biological degradation of the dissolved organic compounds. Tanks are used for settling of solids & for aeration of bacteria. C. Tertiary treatment. Removes plant nutrients especially nitrates & phosphates. Passage through a wetland or lagoon is usually used. Effluent (what is left) is treated with a disinfectant. (Chlorine, UV light or ozone) & de-chlorinate!
1. Natural or artificial wetlands. A series of ponds are used for solid settling & effluent flowing through the marshes is filtered & cleansed by aquatic plants & microorganisms. The marsh becomes a wildlife area. (Arcata, CA) 20 – 30 days of exposure to sun, air & aquatic plants is usually enough to make the water safe.
In Arcata, CA a 160 acre garbage dump was transformed into a series of ponds & marshes that serve as a simple, low-cost waste treatment facility. The city saved millions of dollars. Usually 20 to 30 days of exposure to sun, air, & aquatic plants is enough to make the water safe.
Large, duckweed lagoons are inexpensive, low-tech sewage treatment plants in developing countries. Conventional wastewater treatment can cost $300 – 600 per person served a duckweed system can cost 1/10 as much. The duckweed can then be harvested & used as feed, fuel or fertilizer.
Municipal water treatment.
WATER LAWS 1972 Clean Water Act 1972 Clean Water Act: Goal was to make all U.S. surface waters “fishable & swimable”. To restore & maintain the chemical, physical, & biological integrity of the Nation’s waters. It regulates everything from urban runoff, industrial discharges, & municipal sewage treatment to land-use practices & wetland drainage.
The Act made it unlawful for any person to discharge any pollutant from a point source into navigable waters, unless a permit was obtained under its provisions. It also funded the construction of sewage treatment plants under the construction grants program and recognized the need for planning to address the critical problems posed by nonpoint source pollution. Subsequent enactments modified some of the earlier Clean Water Act provisions. Revisions in 1981 streamlined the municipal construction grants process, improving the capabilities of treatment plants built under the program. Changes in 1987 phased out the construction grants program, replacing it with the State Water Pollution Control Revolving Fund, more commonly known as the Clean Water State Revolving Fund. This new funding strategy addressed water quality needs by building on EPA-State partnerships.
Best Practicable Control Technology BPT: Best Practicable Control Technology BPT: Required for specific point sources of pollution like sewage outfalls & industrial discharge. Best Available, economically achievable Technology Best Available, economically achievable Technology: For toxic substances & requires zero discharge for 126 priority toxics. OTHER IMPORTANT LEGISLATION: Safe Drinking Water Act 1972: Safe Drinking Water Act 1972: to protect the quality of drinking water in the U.S. This law focuses on all waters actually or potentially designed for drinking use, whether from above ground or underground sources. Superfund & CERCLA (SARA)
1972 Great Lakes Water Quality Agreement 1972 Great Lakes Water Quality Agreement between Canada & the U.S. 1978, signed by the U.S. and Canada, where the two nations agreed to reduce certain toxic pollutants in the Great Lakes. That law required EPA to establish water quality criteria for the Great Lakes addressing 29 toxic pollutants with maximum levels that are safe for humans, wildlife, and aquatic life. It also required EPA to help the States implement the criteria on a specific schedule.
1990 London Dumping Convention 1990 London Dumping Convention phasing out all ocean dumping of industrial waste, tank-washing effluent & plastic trash by = Law of the Sea Treaty. The purpose of the Convention is to control the disposal of land-based waste in the sea particularly those detrimental to marine resources. From this it is clear that the wastes from fishing vessels are not covered by the London Convention, but are contained in the MARPOL Convention. MARPOL International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto (MARPOL 73/78)
1998 EPA began watershed-level monitoring & protection. Total maximum daily loads (TMDL) for each pollutant & water body are required to be set by each state. Allowances are made for smart growth initiatives. Most pollution comes from non-point sources. [A cow produces 66 lbs. of manure a day = 10 people. A feedlot can accommodate 100,000 cows!] Nitrate & phosphates have been reduced by point sources but increased 4x’s since 1972 from non-point. Fossil fuel consumption is a major source of nitrates, sulfates, arsenic, cadmium & mercury & other toxics.