title: Effect of polyaluminium chloride on phosphorus removal in constructed wetlands treated with swine wastewater.
abstract: Total phosphorus (TP) removal in aged constructed wetlands poses a challenge, especially when treated with swine wastewater with high concentrations of phosphorus (P). Our earlier studies with anaerobic lagoon swine wastewater treatment in constructed wetlands showed a decline in P removal (45-22%) with increased years of operation. These particular wetlands have been treated with swine wastewater every year since the first application in 1997. Preliminary lab-scale studies were conducted to evaluate the efficiency of polyaluminium chloride (PAC) in the removal of phosphate-P (PO4-P) from swine wastewater. The experimental objective was to increase the phosphorus treatment efficiency in constructed wetland by adding PAC as a precipitating agent. PAC was added by continuous injection to each wetland system at a rate of 3 L day(-1) (1:5 dilution of concentrated PAC). Swine wastewater was added from an anaerobic lagoon to four constructed wetland cells (11m wide x 40m long) at TP loads of 5.4-6.1 kg ha(-1) day(-1) in two experimental periods, September to November of 2008 and 2009. Treatment efficiency of two wetland systems: marsh-pond-marsh (M-P-M) and continuous marsh (CM) was compared. The wetlands were planted with cattails (Typha latifolia L.) and bulrushes (Scirpus americanus). In 2008, PAC treatment showed an increase of 27.5 and 40.8% of TP removal over control in M-P-M and CM respectively. Similar trend was also observed in the following year. PAC as a flocculant and precipitating agent showed potential to enhance TP removal in constructed wetlands treated with swine wastewater.
authors: Department of Natural Resources and Environmental Design, North Carolina A&T State University, Greensboro, NC 27411, USA. reddyg@ncat.edu
authors: G B
authors: GB
authors: Reddy
authors: Dean A
authors: DA
authors: Forbes
authors: P G
authors: PG
authors: Hunt
authors: Johnsely S
authors: JS
authors: Cyrus
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry*; D000822:Animal Husbandry / Q000592:standards; D000818:Animals; D009657:North Carolina; D010758:Phosphorus / Q000302:isolation & purification*; D063245:Plant Development; D012621:Seasons; D013552:Swine; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; C016213:aluminum oxychloride; D010758:Phosphorus; D000536:Aluminum Hydroxide