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841 25 Wetlands by Application Group The strategy of this book up to here has considered individual wastewater constituents by analysis of the available data and in terms of the types of wetlands that may be employed to reduce concentrations of those individual chemicals. That might be termed a horizontal approach because removal of, say, biochemical oxygen demand (BOD), is a crosscutting issue that affects many types of efuents. Primary emphasis has been on the reduction of specic contaminants, includ- ing BOD, total suspended solids (TSS), nutrients, metals, and hydrocarbons. In this chapter, a “vertical” approach is taken, in which particular treatment wetland applications are considered as a group. This is done because some technology growth areas are very application specic. It is not necessary to repeat the many details already presented in two key application areas— metals and hydrocarbons—because each has had an entire chapter already (Chapters 11 and 13). Likewise, the general application area of stormwater runoff has been singled out for an entire chapter (Chapter 14). There remain several applica- tions that deserve additional attention because they present unique features that can inuence design. These include wet- land treatment of animal waste, food wastes, landll leachate, and chemical industry efuents. 25.1 ANIMAL WASTES C ONFINED ANIMAL OPERATIONS Liquid animal wastes consist of manure, ushwater, and rainfall. The Agricultural Waste Management Field Hand- book (USDA-NRCS, 1992) provides information on vol- umes of manure (feces and urine) and mass excretion rates of nutrients for different types of livestock. Average quantities of nitrogen, phosphorus, and BOD 5 in manure are given in Table 25.1. Solid wastes consist of manure and sometimes bedding material such as straw. These amounts are then diluted with water, and the amount of water added to the sys- tem usually exceeds the amount of manure. For cattle and dairy facilities in the United States, 160–200 L/d per cow are used for ushing requirements for freestall alleys (CH2M Hill and Payne Engineering, 1997). Swine ushing quantities are typically 60–95 L/d per adult animal. However, Tanner and Kloosterman (1997) use a lower water rate of 50 L/d per cow, and the French use an even lower range, from 5–15 L/d per cow (Liénard et al., 2002). Operators use a variety of methods to manage wastewater, including lagoons, ponds, storage structures, compost areas, lters, and sediment basins. Liquid wastes are typically col- lected and treated in one or more lagoons before being land applied. The organic matter and nutrients in manure are impor- tant resources that are recycled to the land, if possible, to foster crop production. Solid and slurry wastes usually have very high nutrient concentrations and are good soil amendments, but, in many cases, it is not feasible to collect and contain all animal waste. Some portions are leached from loang lots, and spills occur. In other cases, the availability of cropped land does not accommodate the entire waste production. A constructed wetland offers another option for polishing wastewater before it is recycled as ushwater, land applied, or ultimately discharged. As for other wastewater types, the goal is to prevent manure from being discharged to receiving waters. In natural recipients, the organic matter and nutrients promote algal growth and deplete dissolved oxygen, or in other words, promote eutrophication. Wetland treatment can be implemented on farms in cold climates. Systems have been evaluated across Canada, from Alberta (Reimersma, 2001) to the Atlantic Provinces (Smith, 2003; Smith et al., 2006). Other cold-climate applications have been reported in Germany (Kern and Carlow, 2000; Kern, 2003). These low-technology, solar-driven systems are passive and user-friendly, and thus farmers do not need to acquire the skills of wastewater treatment plant operators. The operation of a wetland system is closely related to cur- rent farming practices. The wetland system requires sunlight, nutrients, and water, but does not need to be harvested. The treatment wetland plants can tolerate relatively high concen- trations of nutrients, but full-strength wastes should not be applied directly to wetlands because many wetland plants cannot tolerate the high nutrient levels. The use of wetlands for treating concentrated animal wastes gained a measure of popularity in the early 1990s. The Brenton cattle operation in Iowa, which started in 1930, was the oldest system in North America found by CH2M HILL (1997). Other early sites include Sand Mountain, Alabama, started in 1989, and the Newton and Hattiesburg, Mississippi, systems, also started in 1989. In the mid-1990s, data collec- tion efforts catalogued the performance of 68 wetland sys- tems in North America (DuBowy and Reaves, 1994; CH2M Hill and Payne Engineering, 1997; Knight et al., 2000). Design procedures are offered, which generally fall in the two categories of loading methods and rate constant methods (CH2M Hill and Payne Engineering, 1997). Examples are included here to illustrate the breadth of applicability for several types of animal operations. © 2009 by Taylor & Francis Group, LLC 842 Treatment Wetlands POULTRY Example: Auburn Poultry Three systems of free water surface (FWS) constructed wet- lands were prepared at the Alabama Agricultural Experiment Station’s (AAES) Poultry Science Unit at Auburn University in Auburn, Alabama, in June 1992 (Rogers et al., 1995; Hill and Payton, 1998). Each system consisted of two cells in series, one planted with Phragmites and Scirpus, a second with Sagittaria lancifolia, while the third series acted as an unvegetated control. Each wetland cell was 5.5 m wide, 30.5 m long with an average depth of 30 cm, and lined with 10 cm of bentonite clay. Subsystems of wooden dowels were tested within the open water system. The wetlands inuent was taken from the rst cell of the lagoon system fed by the caged layer poultry operation, and the wetland efuent owed to a hold- ing pond nearby. A hydraulic loading rate of 3.1 cm/d was applied to each system, which resulted in chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN) loading rates of 145 and 30 kg/ha·d, respectively. In order to deter- mine plant porosity blockage and thus also to assist in calcula- tion of detention time, water column displacement tests were performed. The measured values were 10.7% and 7.0% for Phragmites and Sagittaria, respectively. The detention time was calculated to range from 11.1 to 11.6 days. The concen- tration reductions are shown in Table 25.2, and ranged from 40–60% for the principal contaminants for the vegetated sys- tems. It was expected that temperature would have positively TABLE 25.1 Approximate Waste Quantities for Animals on the Basis of 100 kg Weight Nitrogen (g/d·100 kg) Phosphorus (g/d·100 kg) BOD 5 (g/d·100 kg) Swine Growers 42 15 207 Replacement gilts 24 9 108 Gestating sows 20 7 84 Lactating sows 46 15 200 Boars 15 51 66 Nursery pigs 59 24 339 Dairy cattle Lactating cow 44 7 161 Dry cow 35 5 119 Heifer 31 4 130 Beef cattle Forage feeder 31 11 137 Energy diet feeder 29 9 137 Yearling 31 10 130 Cow 33 12 119 Poultry Laying hens 84 31 370 Human 70 kg 19 2.3 26 Source: Adapted from data in CH2M Hill, Payne Engineering (1997) Constructed wetlands for ani- mal waste treatment. Report to the Gulf of Mexico Program Nutrient Enrichment Committee, U.S. EPA: Stennis Space Center, Mississippi. TABLE 25.2 Removal Efficiencies (%) during 1993–94 for the Auburn Poultry FWS Treatment Wetlands BOD 5 COD TKN NH 4 -N Inlet concentration (mg/L) 233 535 135 121 Sagittaria 50 61 43 38 Scirpus and Phragmites 46 62 57 53 Water 49 54 46 44 Dowels 10% 30 28 20 20 Dowels 5% 35 40 27 26 Source: Adapted from Rogers et al. (1995) In Versatility of Wetlands in the Agricultural Landscape. Campbell (Ed.), American Society of Agricultural Engineers, St. Joseph, Michigan; and Hill and Payton (1998) Transactions of the American Society of Agricultural Engineers 41(2): 393–396. © 2009 by Taylor & Francis Group, LLC Wetlands by Application Group 843 affected treatment of several of the parameters under study, but treatment showed little correlation to water temperature (Hill and Payton, 1998). CATTLE Wetlands are used to manage feedlot runoff, dairy cattle waters, and pasture waters. Two fairly distinct situations may be found in the use of treatment wetlands for cow operations: pastures and feedlots versus dairies. Pastures and feedlots are primarily event-driven, runoff control systems, whereas dairies are con- cerned with water originating in milking parlors, comprised of cleaning waters. The two are considered separately here. Pasture runoff has only been recently considered for treat- ment. The studies of Tanner and coworkers in New Zealand have utilized modern design concepts and made extensive measurements, which form the beginnings of a performance knowledge base (Tanner et al., 2003; Tanner et al., 2005b). Because some pastures are tile-drained, there is sometimes the possibility of directing tile drainage to constructed wet- lands (see Figure 14.8, Chapter 14). The density of animals on the contributing watershed is typically low, and therefore the concentrations of nutrients and other contaminants is rel- atively low (e.g., 10–20 mg/L nitrogen). Further, speciation of nitrogen favors nitrate as the dissolved form, rather than ammonia, because the inltration through the vadose zone provides for nitrication. Feedlots present a different situation because the density on the contributing watershed is high. Nitrogen is almost all in the form of organic and ammonia (TKN), and concentra- tions of all pollutants are high in the direct runoff. One of the earliest constructed wetlands was a two-cell FWS system built in 1930 at the Brenton Brothers feedlot in Dallas County, Iowa, which serves a 26-ha feedlot that typically has 7,000 head of cattle. The rst wetland cell, of extremely irregular shape, comprises 25 ha and receives rain-driven runoff from the feedlot. Over a two-year study period, there were reduc- tions of 87% BOD, 60% TSS, and 58% TKN. This system was one of the two included in the North American Livestock Database (CH2M Hill and Payne Engineering, 1997). Subse- quently, other wetland systems have been tested, with good results. For instance, runoff from Iowa State University’s 380 head beef cattle concrete feedlot was treated via solids settling, soil inltration, and a small constructed wetland, in series (Lorimor et al., 2003). Concentrations and nutri- ent mass ows were reduced by over 97% for TKN, 94% for total phosphorus, and 93% for TSS. No buildups in the system were observed over ve years. The authors concluded that the passive treatment system could very effectively pro- tect surface-water quality below open beef feedlots. In their review of vegetated systems for cattle runoff control, Koelsch et al. (2006) found that virtually all of the existing informa- tion was from non-CAFO (Conned Animal Feeding Opera- tions) situations, i.e., dairies. These authors concluded that critical design factors included pretreatment, sheet ow, dis- charge control, siting, and sizing, together with maintenance of a dense vegetation stand. E xample: Cattle The Canadian livestock farming community is generally not required to meet the strict surface-water discharge regulations imposed on municipalities and industries. However, farming operations generate high levels of nutrients and bacteria that originate from manure storage and application areas, manure storage tank overows, and feedlot runoff, and there is a need to intercept and reduce these contaminant loads. Demonstra- tion of treatment wetland technology was the prime objective in constructing demonstration wetland systems in Manitoba in 1996. Full-scale wetland projects were constructed at two cattle feedlot operations in the Interlake Region of Manitoba (Pries and McGarry, 2001). The second constructed wetland, described here, was at an 1,800-head feedlot bordering Lake Manitoba in the Interlake area, commissioned in 1998. The treatment wetland was constructed to reduce the nutrient and solids loading to Lake Manitoba. The project captures the feedlot runoff, stores it in a holding pond, and then treats the wastewater in constructed wetland cells operated during approximately 150 days each year from mid-May through mid-October. The 0.25-ha hold- ing pond collects and stores contaminated runoff from the feedlot area during the late fall, winter, and early spring, and has a working volume of approximately 3,300 m 3 . The aver- age hydraulic retention time (HRT) in the pond during the wetland operating period is approximately two months. The stored water is pumped to the wetland cells; the topography does not allow for gravity ow. The treatment wetland consists of two 0.5-ha cells oper- ating in parallel with an average depth of 0.3 m and a work- ing volume of 3,000 m 3 . Flow to each of the wetland cells is controlled by gate valves. For normal operation, the gate valves at the weir box are opened to allow a maximum ow of about 100 L/min to each cell. The ow enters the wet- land in the center of the width of an inuent distribution deep zone, which distributes the water across the width of each cell. Treated water is discharged at the efuent level control structure with a weir for ow measurement. In dry years there may be no outlet discharge due to water removal through high rates of evapotranspiration. The holding pond provided considerable treatment prior to discharging the contaminated stormwater to the wetland. Table 25.3 presents the average annual data from monthly samples for two years of operation. The wetland efuent BOD 5 was 15 mg/L or less throughout both years, and the TSS was also consistently less than 15 mg/L. Inow ammonia averaged 2.1 mg/L, with excursions to 4.8 mg/L, but the efu- ent ammonia-nitrogen was less than 0.5 mg/L. Phosphorus reduction was consistent each year with lower concentrations in the efuent than was measured in the inuent. DAIRY OPERATIONS Dairy operations can be major contributors of nutrients to the watersheds in which they are located. For instance, in a nutri- tion study, it was found that cowsexcreted 88.2% of phosphorus © 2009 by Taylor & Francis Group, LLC 844 Treatment Wetlands consumed daily: 68.6% in feces, 1.0% in urine, and 30.3% in milk (Morse et al., 1992). Current and abandoned dairy systems in South Florida’s Lake Okeechobee watershed have a demonstrated phosphorus pollution potential (Nair et al., 1995). In Ireland, about 25% of the land area is devoted to dairy farming, and it is estimated that the percentage of pol- lution attributed to agriculture is approximately 32% in rivers and streams that are slightly to moderately polluted. Most dairies produce two types of waste streams: “white” water, which is dened as the wastewater produced during cleaning and sterilization of the milking equipment, and “green” water, which is wastewater resulting from the wash- down of the manure-spattered walls and oors of the milking parlor and the associated holding pen or staging areas. The combination of these two waste streams produces the “typi- cal” milkhouse wastewater. Because each dairy is different, the ratio of white water to green water will vary. Some farms may have existing manure treatment lagoons, which may be used as pretreatment device for the wetland treatment sys- tem. A typical dairy waste treatment schematic is shown in Figure 25.1. Constructed wetlands have been demonstrated to be effective add-ons to supplement the treatment afforded by farm dairy pond systems. Farm dairy ponds provide for the return of a signicant proportion of the nutrient loading to the pasture via periodic desludging, but the water discharges are not sufciently good to protect receiving water quality (Table 25.4; see also Table 25.3). This application has spurred considerable research over the past decade (Geary and Moore, 1999; Karpiscak et al., 1999; Newman et al., 2000; Hunt and Poach, 2001; Shamir et al., 2001; Kowalk, 2002; Ibekwe et al., 2003; Forbes et al., 2004a; Dunne et al., 2005c; Smith et al., 2006; Healy et al., 2007). Cronk (1996) identied 40 dairy treatment wetlands in North America, established between 1989 and 1993. A database compilation in 1996 identied 60 constructed wetlands at 38 sites in North America (CH2M Hill and Payne Engineering, 1997; Knight et al., 2000). How- ever, a large number of systems have been built, starting in the late 1990s. For instance, by 2004 there were 12 FWS wetlands in the Anne valley of County Wexford in Ireland (Figure 25.2) (Carroll et al., 2005). In general, these systems have large surface areas, averaging 120 m 2 /cow, and provide excellent water quality improvement (Table 25.4). Although dairy wetlands have primarily been FWS, hori- zontal subsurface ow have also been implemented (Tanner et al., 1995a; Tanner et al., 1995b; Mantovi et al., 2003; Kern, 2003). Tanner and Kloosterman (1997) recommend HSSF as an add-on to FWS, presumably because of the potential for clogging of a gravel bed with direct lagoon discharges. The New Zealand wetland design guidelines suggest about 1.0 m 2 /cow for this post-FWS application (Tanner and Kloos- terman, 1997). However, if a HSSF system is to be used as a “stand- alone” device, more area is required to achieve good pollut- ant reductions. In the United Kingdom, a HSSF wetland was used to treat inuent with an average BOD 5 of 1,192 mg/L on a dairy farm in Drointon (Cooper et al., 1996). An area of 250 m 2 for 160 cows (1.6 m 2 /cow) proved unacceptable, and vertical ow wetlands were subsequently installed ahead of the HSSF system. A 95% reduction in BOD 5 was achieved (Figure 25.3). In Germany, an area of about 10 m 2 /cow pro- duced reductions of 91% COD, 86% total nitrogen (TN), and 99% fecal coliforms (FC), with better nutrient reductions in winter (Kern, 2003). A HSSF system in Italy dimensioned at 1.84 m 2 /cow (at a measured 80 L/d per cow) was successful in reducing BOD from 451 mg/L to 28 mg/L, for a settled inuent from Imhoff tank pretreatment (Mantovi et al., 2003). Total nitrogen was reduced from 65 to 33 mg/L, due to miner- alization of organic nitrogen, because ammonia removal was nonexistent. It should be noted that European dairy wetlands TABLE 25.3 Manitoba Interlake Site 2: Average Annual Concentrations in the Wetland Inflows and Outflows Average Value 1999 Average Value 2000 Parameter Inflow Outflow Inflow Outflow BOD 5 (mg/L) 20 4 27 7 NH 3 -N (mg/L) 2.1 0.4 1.4 0.1 TKN (mg/L) 25 16 32 15 TP (mg/L) 6 4.3 8.5 5 TSS (mg/L) 21 6 73 31 pH 8.1 8.1 8.3 8.2 Conductivity (µs/cm) 3,377 3,139 3,629 29,54 COD (mg/L) 247 280 303 222 Fecal coliform (col/100 mL) 420 201 1,082 324 Total coliform (col/100 mL) 11,848 1,496 14,044 25,58 DO (mg/L) 1.2 2.2 3.1 4.8 Source: From Pries and McGarry (2001) Constructed Wetlands for Feedlot Runoff Treatment in Manitoba. Proceedings of the 2001 Water Environment Association of Ontario Technical Conference; Toronto, Ontario. Reprinted with permission. © 2009 by Taylor & Francis Group, LLC Wetlands by Application Group 845 do not usually have a lagoon for pretreatment, although that is the norm in North America and New Zealand. Therefore, direct comparisons are difcult. Research is being directed to more highly oxygenated systems, such as forced aeration or vertical ow wetlands (Whitney, 2003). Vertical ow wetlands have high rates of oxygen transfer and are capable of handling high oxygen demands of milk-house wastes (Green et al., 2002). Rec- ommended vertical ow wetland criteria for dairy waters in France total 0.22–0.44 m 2 /cow in two stages in each of two Anaerobic pond Farm dairy Facultative pond Constructed wetland Dispersal drain Vegetated farm drain Stream FIGURE 25.1 Concept for a farm dairy treatment wetland system. (From Tanner and Kloosterman (1997) Guidelines for Constructed Wetland Treatment of Farm Dairy Wastewaters in New Zealand. NIWA Science and Technology Series No. 48, National Institute of Water and Atmospheric Research (NIWA): Hamilton, New Zealand. Reprinted with permission.) TABLE 25.4 Constructed Wetlands for Farm Runoff in the Anne Valley near Waterford, Ireland BOD 5 TSS NH 4 -N Runoff Type Area (m 2 )Cowsm 2 /Cow In (mg/L) Out (mg/L) In (mg/L) Out (mg/L) In (mg/L) Out (mg/L) Dairy 6,081 60 101 7,194 12 1,141 13 184 0.3 Dairy 22,025 60 367 510 31 532 24 64 0.5 Dairy, beef 10,290 50 206 447 26 136 20 56 0.8 Dairy 10,340 100 103 521 34 1,119 52 119 3.1 Dairy, tillage 3,950 35 113 313 19 136 14 51 0.6 Dairy 12,710 80 159 213 19 210 22 39 0.3 Beef 3,942 — — 59 3 43 9 22 0.2 Mixed 7,958 55 145 494 12 459 15 41 0.6 Mixed 4,380 50 88 171 14 165 20 40 0.4 Dairy 7,690 77 100 694 21 693 18 40 0.4 Mixed 10,726 85 126 2,245 17 3,089 24 266 0.7 Sheep, tillage 3,621 — — 50 16 200 20 13 0.1 Median 120 471 18 335 20 46.0 0.5 Source: Data from Carroll et al. (2005) In Nutrient Management in Agricultural Watersheds: A Wetland Solution. Dunne et al. (Eds.), Wageningen Academic Publishers, Wageningen, The Netherlands. © 2009 by Taylor & Francis Group, LLC 846 Treatment Wetlands trains (Liénard et al., 2002). As for other VF systems, dairy VF wetlands are pulse loaded to induce hydrodynamic move- ment of air through the wetland bed. The practitioner can nd several design guidelines docu- ments (CH2M Hill and Payne Engineering, 1997; Tanner and Kloosterman, 1997; Forbes et al., 2004a). However, the sup- porting data is in the process of being strengthened at this time, as the various authors note, and improvements are to be expected as more operating data become available. Rate con- stants for dairy FWS can be found in the literature, in Payne Engineering and CH2M HILL (1997). In general, these are within the distributions presented in earlier chapters of this book, and indeed the dairy data were included in those deter- minations. McGechan et al. (2005) give rate constants for HSSF and VF dairy systems for nitrogen processing for meso- cosms for dilute farm inuents. However, loading specica- tions are more typically used to interpret data and for design. As an example, one set of median-loading recommendations for FWS systems is shown in Table 25.5. It should be noted that those loadings correspond to fairly large wetland areas, comparable to those used in the Irish systems in Table 25.4. Those dairy loading recommendations are comparable to, but somewhat less than, those recommended by U.S. EPA for municipal wastewaters. Nitrogen reductions are in general less than for BOD and TSS. Dairy wastewaters differ from most municipal and domestic wastewaters in that they contain a relatively high amount of organic nitrogen. For instance, the database used in this book shows a median inlet organic nitrogen of 37 mg/L for animal treatment wetlands, whereas the median FIGURE 25.2 Farm wetland in the Anne valley near Waterford, Ireland. This FWS system takes advantage of a downhill location from the barns and yards to employ gravity ow. FIGURE 25.3 Performance of the rst and second iterations of the Drointon, U.K., reedbeds for farm waste treatment. In the rst case, the BOD loading to the HSSF wetland was 255 kg/ha·d, and in the second case it was 35 kg/ha·d. (Based on Cooper et al. (1996) Reed Beds and Constructed Wetlands for Wastewater Treatment. WRc Publications, Swindon, United Kingdom.) BOD: 2,450 mg/L TSS: 1,281 mg/L BOD: 1,214 mg/L TSS: 633 mg/L 608 mg/L 506 mg/L BOD: 2,158 mg/L TSS: 865 mg/L November 1988–September 1989 October 1990–May 1992 HSSF 250 m 2 BOD: 62 mg/L TSS: 98 mg/L HSSF 250 m 2 VF #2 8.7 m 2 VF #1 26 m 2 336 mg/L 405 mg/L © 2009 by Taylor & Francis Group, LLC Wetlands by Application Group 847 for municipal systems is 7 mg/L. As a consequence, there is a need to mineralize this organic nitrogen before it can be reduced by oxidative and other processes. This additional processing step slows overall nitrogen removal and is partly to blame for low removal rates. Mineralization of the organic nitrogen can increase the ammonia content of the water prior to its nitrication. Ultimately, the loss of total nitrogen sug- gests an implied oxygen supply that is limiting for nitrogen processing. The internal ammonia load created by mineral- ization of organic nitrogen adds to the incoming ammonia. The rates of nitrogen removal in animal wetlands are strongly suggestive of mechanisms other than traditional nitrication– denitrication. Oxidized nitrogen is rarely a signicant com- ponent of inuents or efuents from dairy water wetlands. This is speculatively due to an adequate carbon supply and rapid denitrication, and perhaps also due to Anammox or similar alternative processing mechanisms (see Chapter 9). Example: Dairy Farm Operations A study on a three-cell integrated FWS system in County Wexford, Ireland, was conducted over a 2.5-year period (Dunne et al., 2005a; Dunne et al., 2005b). Water from farm- yard management and dairy operations for a 42-cow facility were collected in a central storage tank before discharge to the wetlands. The three cells had a combined area of 4,265 m 2 (102 m 2 /cow) and were maintained at a 30–40-cm depth. A 250-m 2 sedimentation basin preceded the treatment marshes. The vegetative cover was 80–90% during the grow- ing season, and comprised of a mixture of Carex riparia, Typha latifolia, Phragmites australis, Sparganium erectum, and other emergent species. The ow rate to the wetlands averaged 7.6 m 3 /d (180 L/cow·d), and was greatly augmented by rainfall (1,142 mm/yr) to produce an outow rate of 31.1 m 3 /d. As a result, there were considerable differences between mass reductions and concentration reductions (Table 25.6). Part of the observed concentration reduction was attributable to dilution. Nonetheless, this lightly loaded system produced very good removals, but with lesser per- formance in winter for ammonia and phosphorus. It is note- worthy that the implied maximum oxygen supply was about 4.8 gO/m 2 ·d, which is a feasible reaeration rate. It is also the case that the nitrogen supply places these wetlands in the group with agronomic control. BOD and TSS are reduced to what TABLE 25.5 Median-Loading Recommendations for FWS Animal Wastewater Wetlands (kg/ha·d) Effluent Target 20 mg/L 30 mg/L 40 mg/L 100 mg/L BOD 5 20 33 51 100 TSS 15 30 61 135 TN 8 10 27 61 TP 11 18 28 56 U.S. EPA BOD 5 45 40–60 — — Source: Adapted from data in CH2M Hill, Payne Engineering (1997) Constructed wetlands for animal waste treatment. Report to the Gulf of Mexico Program Nutrient Enrichment Committee, U.S. EPA: Stennis Space Center, Mississippi; and U.S. EPA (2000b) Constructed wetlands: Agricultural wastewater. EPA 843/F-00/002, U.S. EPA Ofce of Water. TABLE 25.6 Summary Performance of the Teagasc FWS Dairy Wetlands, Located at the Teagasc Research Center, Johnstown Castle, Wexford, Ireland Flow (m 3 /d) SRP (mg/L) NH 4 -N (mg/L) BOD 5 (mg/L) TSS (mg/L) Inlet 7.6 19 48 2,629 980 Outlet 31.1 1.7 1.9 20 11 Concentration reduction 91% 96% 99% 99% S RP (g/m 2 ·yr) NH 4 -N (g/m 2 ·yr) BOD 5 (kg/ha·d) TSS (kg/ha·d) Inlet 12.0 31.2 46.8 17.5 Outlet 4.5 5.1 1.5 0.8 Mass removal 62% 84% 97% 95% Source: Data from Dunne et al. (2005c) Ecological Engineering 24(3): 221–234. © 2009 by Taylor & Francis Group, LLC 848 Treatment Wetlands appear to be background concentrations because there was little change in concentrations after the rst two wetlands. SWINE Swine wastewaters are strong efuents that received only minimal treatment in past years. A very popular system in the southeastern United States is an anaerobic lagoon fol- lowed by a spray irrigation system. In North Carolina, there are 4,500 active and 1,700 inactive swine waste lagoons (Humenik et al., 2004), but these are no longer permitted because of problems with overow and leakage. Constructed wetlands are a logical add-on, and therefore investigations on their effectiveness were initiated, approximately in 1990, at Auburn University’s Sand Mountain Agricultural Experiment Station in DeKalb County, Alabama (Hammer et al., 1993a; McCaskey et al., 1994). Another facility followed soon after (1991) at the Pontotoc, Mississippi, Experiment Station (Cathcart et al., 1994). Based on early swine wetland data and the performance of municipal treatment wetlands, design recommendations quickly proliferated (USDA-NRCS, 1992; Hammer, 1994). Loading numbers of approximately 60–70 kg/ha·d for BOD were suggested. In fact, FWS swine wet- lands are at the poor performance edge of the municipal con- centration-loading band (Figure 25.4), and this loading now appears likely to produce 60–80 mg/L BOD in the wetland outow. This may be due to the much higher concentrations in swine wastewater (Cronk, 1996). Research intensied in the mid-1990s, with projects in North Carolina and Indiana. Investigations were conducted from 1992 to the present at a continuous marsh site in the eastern coastal plain in Duplin County, and at a marsh–pond–marsh site in Greensboro at North Carolina A&T State University. The site descriptions and operational procedures are reported in a number of pub- lications (Hunt et al., 1994; Reddy et al., 2001; Stone et al., 2002; Poach et al., 2003; Stone et al., 2004). The Purdue Uni- versity system at West Lafayette involved 16 FWS wetland cells operated in a designed experimental array (Reaves et al., 1994). These studies all showed signicant reductions in BOD, TSS, and total nitrogen, but the removal percentages were not outstanding (Table 25.7). Because of the high ammonia levels in swine lagoons and wetlands, there has been concern that ammonia volatil- ization could be a problem. A study was conducted to address the concern that nitrogen removal was due to high ammonia volatilization. Poach et al. (2002; 2004) documented that less than 10% of the input nitrogen was lost by ammonia vola- tilization (see Figure 9.7, Chapter 9). However, as for other animal wastes, the organic nitrogen content is high, and a mineralization step must precede ammonia conversions. The process of denitrication is greatly assisted by the availability of organics and carbon, with the result that oxidized nitrogen is not present in the waters, and by the fact that redox poten- tials are generally quite low (Hunt et al., 2003; Szögi et al., 2004). Nitrogen processing in swine wetlands is quite tem- perature dependent, as for other FWS systems. However, that does not preclude their use in cold climates during the unfro- zen season, even as far north as Alaska (Maddux, 2002). Subsurface ow wetlands have also been used to treat swine efuents in North America (Sievers, 1997) and else- where around the world (Lee et al., 2004b). However, the high TKN concentrations also cause problems with respect to oxygen supply in HSSF systems. Therefore, vertical ow systems have also been piloted (Kantawanichkul et al., 1999; Sezerino et al., 2003). As an alternative to vertical ow, a ll-and-drain mode has been employed with good success (Behrends et al., 2003; Rice et al., 2005). This concept involves continuously pumping wastewater back and forth FIGURE 25.4 The position of swine treatment wetlands compared to all other FWS systems. © 2009 by Taylor & Francis Group, LLC Wetlands by Application Group 849 between adjacent cells on a two-hour cycle. This vertical ow design provides aeration of the gravel substrate and exposes the internal biolms to atmospheric oxygen. During the “drain phase” of the cycle, atmospheric oxygen causes enhanced oxidation of ammonia and organic matter. This mode of operation is described further in Chapter 24. Example: Swine In 1995, six wetland systems to treat swine lagoon wastewa- ter were constructed at the North Carolina A&T State Uni- versity farm near Greensboro, North Carolina (Reddy et al., 2001; Stone et al., 2004). The wetland systems were cong- ured into a marsh section, a central pond section, and another marsh section (marsh–pond–marsh). The marsh sections were approximately 10 m r 10 m, and the pond section was 10 m r 20 m. The marsh sections were planted with Typha latifolia and Schoenoplectus americanus in March 1996. Beginning in September 2000, the wetlands were loaded with specic total nitrogen at rates of 5, 14, 23, 32, 41, and 50 kg/ha·d. For one year, the wetland hydraulic loading rates were held approximately equal, with only the TN loading rate varying. The operating depths of the constructed wetlands were 15 cm for marsh sections and 75 cm for pond sections. Mean TN and NH 4 -N concentration reductions were 35 and 25%, respectively. However, the nitrogen performance was on the poor side of the scatter of performances for other FWS wetlands (Figure 25.5). The calculated rst-order plug- ow rate constants (k 20 ) for TN and NH 4 -N were 3.7–4.5 m/d and 4.2–4.5 m/d, respectively, which are considerably lower than the central tendencies given in Chapter 9. These are at about the 10th percentile for FWS wetlands. However, no allowance was made for the internal mineralization of organic nitrogen in the Stone et al. (2004) analysis. ZOOS The Wuhan Zoo, Wuhan City, China, is investigating the use of sedimentation systems and wetlands to reduce nutrient losses from the site to a lake. The project is conducted by the Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing (D’Arcy, 2005). A reed bed has been operating for some years at Chester Zoo in the U.K., treating runoff from its Asian elephant enclosure (D’Arcy, 2005). A vertical ow treatment wetland is used at the Saint- Felicien zoo in Quebec (Pries, 1994). The seals of the Rhe- ine zoo in Westphalia, Germany, have their water recycled back to their basin to cut costs that otherwise would arise by replacing used water with fresh drinking water (Dartmann et al., 2000). The seals produce large amounts of residue that cloud the water, capable of impairing the visitors’ view, espe- cially in deep-water zones. A horizontal ow wetland system is used to lter and clarify the water. AQUACULTURE Fish farming is an increasing activity worldwide, as wild sup- plies dwindle and dietary preferences change. Constructed wetlands have been explored as a means of controlling the associated pollution, notably for catsh, trout, and shrimp operations. However, other sh species have also been the object of treatment wetlands, such as milksh (Chanos cha- nos) (Lin et al., 2002a; Lin et al., 2002b). Catfish Channel catsh (Ictalurus punctatus) farming is the larg- est segment of aquaculture in the United States. Most of the nation’s catsh is raised in Alabama, Arkansas, Louisiana, and Mississippi on 70,000 ha of catsh farms (Tucker, 1999). More farm-raised catsh is produced and sold in these states than all other U.S. aquacultured species combined. In fact, the farm-raised catsh industry enjoyed phenomenal growth over the past 37 years, from 2.6 million kilograms produced in 1970 to more than 275 million kilograms in 2006 (Harvey, 2006). Nearly all commercial aquaculture in the southeastern United States is conducted in earthen ponds. Good produc- tion from ponds is encouraged by using manufactured feeds TABLE 25.7 Examples of Performance of FWS Wetlands for Swine Wastewater TSS BOD TN Site HLR (cm/d) Inlet (mg/L) Load (kg/ha·d) Outlet (mg/L) Inlet (mg/L) Load (kg/ha·d) Outlet (mg/L) Inlet (mg/L) Load (kg/ha·d) Outlet (mg/L) Greensboro, North Carolina 1.1 522 57 164 821 90 383 146 16 71 Greensboro, North Carolina 2.2 522 114 175 821 180 471 146 32 93 Pontotoc, Alabama 1.54 93 14 35 47 7 27 130 20 40 Pontotoc, Alabama 1.27 96 12 31 49 6 23 129 16 47 Purdue, Indiana 1.96 137 27 52 114 22 41 398 78 212 Purdue, Indiana 3.91 136 53 70 114 45 47 407 159 233 Purdue, Indiana 7.83 134 105 82 115 90 51 417 326 265 Note: The Greensboro values are COD, not BOD. © 2009 by Taylor & Francis Group, LLC 850 Treatment Wetlands or increasing the availability of natural foods by adding fertil- izers. Less than 30% of the nitrogen and phosphorus added in feed or fertilizer is recovered at harvest. The remainder of the nutrient load is left in the pond and may be discharged when it rains or when ponds are drained between sh crops. In the United States, aquaculture efuents are regulated under the National Pollutant Discharge Elimination System (NPDES) as part of the Federal Water Pollution Control Act of 1972. A study by the Southern Regional Aquaculture Cen- ter characterized catsh pond efuents from 45 ponds over a two-year period (Tucker, 1999). Efuent quality was poorest in the summer when sh-feeding rates and water tempera- tures are highest. Catsh pond efuents generally have higher concentrations of nutrients and organic matter than natural stream waters, but much lower concentrations than municipal and industrial wastewater. As a result of successful demonstrations, the use of constructed wetlands for nsh production was thoroughly examined by Posadas and LaSalle (1997; 1998). Their report concluded that the use of constructed wetlands was not eco- nomically viable because of the added costs. Kouka and Engle (1994) estimated that wetland treatment would add $0.18/kg to the price of the sh, which is on the order of $1.75/kg (2006 USD) (Harvey, 2006). Example: Catfish In 1992, a two-cell, 2,350-m 2 test wetland was implemented near Greensboro, Alabama (Schwarz and Boyd, 1995). Water from a production pond was passed through the constructed wetlands at HRTs of 1, 2, 3, and 4 days, with hydraulic loading rates of 77–91 L/d·m 2 . Cell one was planted with California bulrush (Scirpus californicus) and giant cutgrass (Zizaniopsis miliacea), and cell two with maidencane (Pani- cum hemitomon). Concentrations of potential pollutants were much lower in efuent from the wetland than in inu- ent from the channel catsh ponds. The mean mass removals were total nitrogen, 61%; biochemical oxygen demand, 62%; suspended solids, 87%; and total phosphorus, 75%. Overall performance of the wetland was not correlated with HRT, but that was clearly because hydraulic loading was held constant while depth was varied. Thus, this data supports the notion that removal is area specic rather than volume specic. The researchers observed that although pond overow and water exchanges could be treated with reasonably sized wetlands, complete pond draining usually proceeds rather rapidly and would create unacceptably high hydraulic loads. Tilapia “Tilapia” is the generic name of a group of cichlids endemic to Africa, consisting of three aquaculturally important genera (Oreochromis, Sarotherodon, and Tilapia). Worldwide har- vest of farmed tilapia has now surpassed 800,000 metric tons, and tilapia are second only to carp as the most widely farmed freshwater sh in the world (Pompa and Masser, 1999). Posi- tive aquacultural characteristics of tilapia are their tolerance to poor water quality and the fact that they eat a wide range of natural food organisms. Indeed, tilapia have been consid- ered as part of a system to improve swine water quality, used in conjunction with wetlands (Dontje and Clanton, 1999). Biological constraints to the development of commercial tilapia farming are their inability to withstand sustained water temperatures below 10 to 15°C. The U.S. imports most of its FIGURE 25.5 Total nitrogen loading graph for the marsh–pond–marsh system at North Carolina A&T University Farm FWS swine wet- lands at Greensboro, North Carolina, compared to the general FWS loading data. The line that represents their swine data (from Stone et al. (2004) Ecological Engineering 23(2): 127–133) is on the upper edge of the cluster of data. et al © 2009 by Taylor & Francis Group, LLC [...]... winery effluents (Kerner and Rochard, 2004) (Figures 25. 11 and 25. 12) As of 2002, there were seven wineries using treatment wetlands to treat winery wastewater in FIGURE 25. 11 Full-scale vertical SSF wetland for treating winery wastewater at Chateau Mont-Redon, Chateauneuf-du-Pape, France © 2009 by Taylor & Francis Group, LLC 856 Treatment Wetlands FIGURE 25. 12 The Grove Mill winery FWS wetland in the Waihopai... investigated FWS wetlands only and produced 60– 70% reduction in COD with two to four days’ detention The second was a prototype for the full-scale system, consisting of a FWS–VSSF–FWS combination In the full-scale project, clarified wastewater is pumped to a 10-ha lined FWS treatment wetland (Figure 25. 8), followed by a 4-ha vertical SSF flow system, then to a 2-ha denitrification FWS treatment wetland,... metabolism and growth, uptake is dependent on concentrations and supplies to the 862 Treatment Wetlands TABLE 25. 12 Tracking of Inlet-Detectable Organic Contaminants through the Isanti-Chisago, Minnesota, Treatment System for Five Years Raw Water Concentration (µg/L) Number of Samples Acetone n-Butyl benzene sec-Butyl benzene tert-Butyl benzene Chlorobenzene Chloroform Chloromethane 1,2 Dichlorobenzene 1,4... typically 20 times more diluted than medium-strength municipal wastewaters and even below municipal secondary treatment criteria (Comeau et al., 2001; Schulz et al., 2003a) With respect to receiving-water-quality objectives, the most constraining element to remove from freshwater fish farms is phosphorus Evaluation of treatment wetlands to treat effluents began in the mid-1990s, with work at the Freshwater... effectively creating a zero-discharge system Any treated water that infiltrates an imperfect mound cap will add to subsequent leachate flows, effectively creating recycle through the mound 864 Treatment Wetlands 300 Inlet Outlet Pilot Inlet Pilot Outlet Ammonia N (mg/L) 250 200 150 100 50 0 0 FIGURE 25. 17 The infiltration wetland at the Isanti-Chisago, Minnesota, leachate treatment wetland facility... Minnesota, site (Figure 25. 17), where the infiltrate system was a leaky constructed wetland Local groundwater flows vented to downgradient wetlands of the region and were not tapped for human use SCALE-UP There are well-known problems that properly limit the scaleup of mechanical plants of various sorts, and treatment wetlands are no exception Conservative designs usually do not exceed a scale-up factor of the... experienced, with a 15-cm head differential along the flow direction The inlet zone became flooded (Figure 25. 19), while the outlet zone became devoid of wetland plants because of too much dry gravel at the top of the profile (see, for example, Figure 21.14, Chapter 21) TABLE 25. 13 Effect of Substrate Depth on Pollutant Removal in HSSF Wetlands Polishing Pretreated Pulp-Mill Effluent at a 15-Hour Retention... The k-C* model does a good job of fitting the batch disappearance of soluble TOC (Figure 25. 6) The rate constant is similar to that obtained from BOD data from numerous domestic wastewater wetlands (see Chapter 8) American Crystal Sugar’s Hillsboro, North Dakota, sugar beet refinery, built in 1973, generates about 260,000 m3 of wastewater during the eight-month processing season The plant uses a 64-ha... (O’Brien et al., 2002) Two have free water surface wetlands, four have subsurface flow wetlands, and one uses both free water surface and subsurface wetlands technology Two additional subsurface wetlands are either under construction or in permitting Targets for treatment are typically COD, TSS, ammonia, and nitrate Performance of these constructed wetlands has been found to depend on the management... al (2004) operated a pilot-scale reed bed for olive mill wastewater treatment Ten-to-one dilution was required to maintain healthy vegetation and gave sustainable removal efficiencies, especially for COD (74.1 17.6%) and polyphenols (83.4 17.8%) 25. 3 LANDFILL LEACHATE Old and new landfills produce leachates, typically formed from infiltrating waters and the products of solid-waste decomposition Those . full-scale project, claried wastewater is pumped to a 10-ha lined FWS treatment wetland (Figure 25. 8), fol- lowed by a 4-ha vertical SSF ow system, then to a 2-ha denitrication FWS treatment. manure treatment lagoons, which may be used as pretreatment device for the wetland treatment sys- tem. A typical dairy waste treatment schematic is shown in Figure 25. 1. Constructed wetlands. and SSF wetlands are in use to improve the quality of winery efuents (Kerner and Rochard, 2004) (Figures 25. 11 and 25. 12). As of 2002, there were seven win- eries using treatment wetlands
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