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Rural, Onsite & Small Community Wastewater & Waste Management. Facultative & Anaerobic Lagoons. Lagoon Systems. Objective Create an ideal environment for microorganisms to consume waste organic matter High strength waste - anaerobic lagoons Wastewater - Facultative lagoons
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Rural, Onsite & Small Community Wastewater & Waste Management Facultative & Anaerobic Lagoons
Lagoon Systems • Objective • Create an ideal environment for microorganisms to consume waste organic matter • High strength waste - anaerobic lagoons • Wastewater - Facultative lagoons • AKA Stabilization ponds
Anaerobic Lagoons • Natural continuation of the breakdown of food in the body • Digestion without oxygen
Acid Formers • Tough • Can produce organic acids over a wide range of environmental conditions • Organic acids • Lower pH of lagoon • Smell bad !!!
Methane Formers • Delicate • Easily upset by • Low pH - below 6.7 • High salt concentration (8mmhos/cm)
Startup • Start in Summer • About 1/2 full of clean water • Slowly add waste at first • Design loading after 1 year
Loading • Continuous • Check pH • Add lime if below 6.7
Pump out • Annually • Down to minimum treatment volume • Avoids salt buildup • If salts are over 8 mmhos/cm • Pump some out and add dilution water
Anaerobic Lagoons • Natural treatment system • No power required • Tend to be large • Dilution • Long treatment time • Low, but daily management
Stabilization Pond • Sometimes called facultative lagoon • Digestion with oxygen • Used to treat wastewater
Stabilization pond • Shallow basin • Microorganisms at natural concentration
Design • BOD loading • Hydraulic residence time • 3 to 12 months
Loading • Can tolerate fluctuations in loading • Keep inlet below surface to control odors
Management • Maintain banks • Keep weeds from growing in water • Keep burrowing animals out • Keep trees from growing
Management • Maintain lnlet & Outlet Structures • Keep sludge from accumulating • Watch for signs of erosion • Exercise valves
Discharge • Ideal for irrigation systems • Appropriate level of treatment • Storage to maximize flexibility for operator
Sludge Management • Debris may wash up on banks • Pretreat with screens • Small amounts of stabilized sludge can be entrained in irrigation system
Stabilization Ponds • Reduced management • No power requirement • Low labor time and training • Limited sludge management
Stabilization Ponds • Large • Treatment takes a long time • Affected by winter conditions
Relative Size Fixed Flim 1x Lagoon 6x
Reduce the Size? • Stirring • Improves air transfer • Increases contact between micoorganisms and waste
Impact of Stirring • Pond can be • Smaller • Deeper • Shorter residence time
Impact of Stirring • Power required • More operator time & training • More sludge is generated
Readings • Hammer & Hammer 413 - 419 • MWPS 18 Section 7.1