Submitted to: Scientia Agricola
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2015
Publication Date: 9/1/2016
Citation: Szogi, A.A., Vanotti, M.B. 2016. Decline of phosphorus, copper, and zinc in anaerobic swine lagoon columns receiving pretreated influent. Scientia Agricola. 73(5):417-423.
Interpretive Summary: Confined swine production generates large volumes of wastewater typically stored and treated in anaerobic lagoons. These lagoons usually require a sludge management plan for their maintenance consisting of regular sludge removal by mechanical agitation and pumping followed by land application. Anaerobic lagoon liquid and sludge are both rich in nutrients, particularly nitrogen (N), phosphorus (P), copper (Cu), and zinc (Zn). However, P can be the limiting nutrient on land requirements for application of lagoon sludge and contributor to environmental P contamination. An alternative to resolve this environmental problem is pretreatment of liquid raw manure prior to lagoon input. The pretreatment of raw swine manure can have the environmental benefits of decreasing the P, Cu and Zn land application rates while reducing the frequency and cost of lagoon sludge removal. In a 15-month study the effect of manure pretreatment on reduction of total suspended solids (TSS), total P, Cu and Zn in swine lagoons was evaluated using (i) enhanced solid–liquid separation with polymer (SS) and (ii) solid–liquid separation plus biological nitrogen treatment using nitrification–denitrification (SS+NDN). A conventional anaerobic lagoon treatment was included as a control. The removal of solids by both pretreatments effectively reduced the net mass input of TP, Cu, and Zn in the lagoon columns with respect to the control. The TP mass input declined by 79% with SS and by 100% with SS + NDN; Cu declined by 91% with SS and 98% with SS+NDN; and Zn declined by 91% with SS and 97% with SS+NDN. The decline in mass accumulation of TP, Cu, and Zn in sludge as a result of reduction of solids input can help minimize both the frequency of sludge removal for lagoon maintenance and the land area for its disposal.
Technical Abstract: Land application of both anaerobic lagoon liquid and sludge can increase nutrient accumulation beyond soil assimilative capacity and become a threat to water quality in regions with intensive confined swine production. In a 15-month meso-scale column study, we evaluated the effect of manure pretreatment on reduction of total suspended solids (TSS), total phosphorus (TP), soluble reactive P (SRP), and total copper (Cu) and zinc (Zn) in swine lagoons using (i) enhanced solid–liquid separation (SS) and (ii) solid–liquid separation plus biological nitrogen treatment with nitrification–denitrification (SS+NDN). A conventional anaerobic lagoon treatment was included as a control. A mass flow balance revealed that with both pretreatments the net mass input of TP, Cu, and Zn in the lagoon columns declined 80 to 100 % when compared to the control. Even though both pretreatments significantly reduced P in the inflow, TP and SRP were negatively correlated (r = -0.51 to -0.87) with TSS in the liquid fraction because of dissolution of P from the sludge into the overlying lagoon liquid. On the other hand, solids removal by both pretreatments effectively reduced Cu and Zn concentrations in the lagoon liquid; their concentrations were positively correlated (r = 0.79 to 0.90) with TSS. The decline in mass accumulation of TP, Cu, and Zn in sludge as a result of reduction of solids input can help minimize both the frequency of sludge removal for lagoon maintenance and the land area for its disposal.