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05/26/2009 13:18 9518273349 DOUGLAS KUNEY PAGE 09/10 <br /> j <br /> .f <br /> Table 5. North Carolina Poultry Aerobic Lagoon Design Criteria '~ <br /> M <br /> 8i rd typo Tjnitt Average Naturally loalaan�aally <br /> Ac�Catad Lagoon <br /> Live Aerobic - -- -J--. --------------- <br /> bird Lagoon S�rface Aeration <br /> Wsisbt Surface Area Area Horsepower <br /> lbs ft2** ft2*** hp**** <br /> ------------------------------------ -- ---------------- <br /> Layer per bird 4..0 11.6 0.30 0.00030 <br /> Pullet per bird 1.5 4.3 0.11 0.00011 <br /> * One-time bird capacity. <br /> ** Loading rate - 50 lbs SOD5/surface acre/day; meat, liquid depth 4 ft <br /> *** 1000 ft2/hp of aeration and a minimum liquid depth — 10 £t. <br /> **** 501 satisfaction of waste COD and oxygen transfei rate of 3 lbs/hp-hr <br /> 1 <br /> Vast amounts of land are required for naturally aerobic lagoons - as much as ^� <br /> 25 times more surface area and 10 times .more volume than an anaerobic lagoon <br /> 10 feet deep. Thus, naturally aerobic lagoons are imptactical for primary <br /> tzeatmcut and are generally not re,coumended for lives took i and poultry manures. <br /> Redbanically Aerated <br /> Mechanically aerated lagoons combine the - odor control advantages of <br /> aerobic digagtion ratty 7reLprively small surface requfr. Tnpnts. Aerators are <br /> used mainly to control odors in sensitive areas and for nitrogen, removal at <br /> limited land disposal sites. Aerated lagoons have suessfully met these <br /> objectives by providing enough oxygen to satisfy 50% o, the waste chemical <br /> oxygen demand (COD) assuming an aerator oxygen transfer rate of 3 pounds per <br /> horsepower-hour. The lagoon liquid surface should not ear4eed 1000 square feet <br /> per horsepower of aeration for floating surface aerators to insure complete <br /> surface influence. Liquid depths should be at least 10 feet. - Table 5 gives <br /> mechanically aerated lagoon design criteria for poultry. <br /> I <br /> A major disadvantage of mechanically-aerated lagoons is the expense of <br /> continually operating electrically-powered aerators. Lamer anaerobic lagoons <br /> may provide similar performance with less expense. Aeratid lagoons also yield <br /> more sludge than anaerobic unite because more input oxgaiea arc amt-terted to <br /> biomass. Suspension of bottom sludge by the aeratorscan cause increased <br /> lagoon liquid concentrations and stimulate foaming. Solids traps such as a <br /> septic tank type settling chamber between primary aerated and secondary <br /> lagoons can provide a convenient mechanism for solids collection and removal. <br /> Kachanically-aerated lagoon liquid nitrogen levels are aiinificantly reduced_ <br /> M_STAGg LAGOONS <br /> I <br /> Two-stage lagoons provide certain advantages over single primary lagoons. <br /> More than two lagoons in series is rarely beneficial. Secondary lagoons <br /> provide temporary storage prior to .Iajad application. Aerobic systems need a <br /> second lagoon to provide storage and allow the primary, lagoon to function <br /> solely four biOlogical treatment. A second lagoon also Mows aa. maximum liquid <br /> volume to be maintained in primary anaerobic lagoons for stabilizing incoming <br /> 32 I <br />