Removal of Phosphorus from Livestock Effluents

Abstract

For removal of phosphorus (P) from swine liquid manure before land application, we developed a treatment process that produces low P effl uents and a valuable P by-product with minimal chemical addition and ammonia losses. Th e new wastewater process included two sequential steps: (i) biological nitrifi cation and (ii) increasing the pH of the nitrifi ed wastewater to precipitate P. We hypothesized that by reduction of inorganic buff ers (NH 4 + and carbonate alkalinity) via nitrifi cation, P could be selectively removed by subsequent hydrated lime [Ca(OH) 2 ] addition. Th e objective of the study was to assess if this new treatment could consistently reduce inorganic buff er capacity with varied initial concentrations of N (100-723 mg NH 4 + L −1 ), P (26-85 mg TP L −1 ), and alkalinity (953-3063 mg CaCO 3 L −1 ), and then effi ciently remove P from swine lagoon liquid. Th e process was tested with surface lagoon liquids from 10 typical swine farms in North Carolina. Each lagoon liquid received treatment in a nitrifi cation bioreactor, followed by chemical treatment with Ca(OH) 2 at Ca rates of 0, 2, 4, 6, 8, 10, and 12 mmol L −1 to precipitate P. Th is confi guration was compared with a control that received the same Ca rates but without the nitrifi cation pretreatment. Th e new process signifi cantly reduced >90% the inorganic buff ers concentrations compared with the control and prevented ammonia losses. Subsequent lime addition resulted in effi cient pH increase to ≥9.5 for optimum P precipitation in the nitrifi ed liquid and signifi cant reduction of effl uent total P concentration versus the control. With this new process, the total P concentration in treated liquid effl uent can be adjusted for on-farm use with up to >90% of P removal. Th e recovered solid Ca phosphate material can be easily exported from the farm and reused as P fertilizer. Th erefore, the new process can be used to reduce the P content in livestock effl uents to levels that would diminish problems of excess P accumulation in waste-amended soils.

Microbial community analysis of swine wastewater anaerobic lagoons by next-generation DNA sequencing

“…The characteristics of these lagoons were typical of swine anaerobic lagoons found in the mid-South United States [3,35,36]. All four lagoons presented as anaerobic, reduced environments, with L3 having an ORP indicative of the potential for denitrification, while the others had values typical of sulfatereduction or methanogenesis.…”

Optimization of struvite precipitation in synthetic biologically treated swine wastewater—Determination of the optimal process parameters

“…> F for %PO4-P as struvite Adjusted R the N:P molar ratio and the nucleation rate of struvite was speeded up (1). Secondly, NH 4 + improves the buffer capacity of the solution [18,35,36]. The nucleation of struvite occurs at a lower pH than the one needed for the precipitation of calcium phosphate [13].…”

Chemical phosphorus recovery from animal manure and digestate : Laboratory and pilot experiments

“…Not only struvite but other minerals coprecipitate as well (Lind et al 2000;Van Rensburg et al 2003;Ekama et al 2006;Ganrot et al 2007;De Graaff 2010;Wu and Zhou 2012). Examples from literature on animal slurries refer often to laboratory experiments (Szogi and Vanotti 2009;Shen et al 2012;Wahal et al 2011;Wendler Fernandes et al 2012;Shepherd, Burns, et al 2009b). Westerman et al (2010) present encouraging results on struvite formation in digestate from swine slurry with a continuous flow bed crystallizer (65% P recovery at a cost of $0.0146/kg of live weight pig slaughter).…”