Effects of Membrane Concentration Processes on Flux, Nutrient Recovery, and Antibiotic Isolation for Anaerobically Digested Slurry from Swine Manure

HighlightsThree membrane concentration processes for anaerobically digested (AD) slurry were investigated.With regard to processing stability and efficiency, NF-RO was recommended for AD slurry concentration.Membrane concentration enables the synchronous recovery of nutrients and removal of antibiotics in AD slurry.Abstract. Membrane concentration processes have been used to treat anaerobically digested (AD) slurry for nutrient recovery and pollutant removal; however, these methods often face the challenges of low processing stability and efficiency. In this study, the performance (processing stability and efficiency) of three membrane concentration processes, including nanofiltration (NF), reverse osmosis (RO1) and two-stage NF-RO (NF-RO2), in treating ceramic membrane-pretreated swine manure AD slurry was evaluated and compared. Nutrient and antibiotic redistribution in the concentrate and permeate was also investigated. Results show that NF-RO2 had higher processing stability and efficiency than the other two processes. High nutrient recoveries of 61.9% for total nitrogen, 56.3% for total phosphorus, and 67.0% for potassium in the concentrates were observed in NF-RO2. The removal rates for antibiotics sulfamethazine and oxytetracycline in NF-RO2 were 99.3% and 81.9%, respectively. Therefore, NF-RO is an effective way to recover nutrients and remove pollutants from AD slurry. Keywords: Antibiotic flow, Nanofiltration, Nutrient flow, Reverse osmosis, Swine manure.

Comparison of Raw Dairy Manure Slurry and Anaerobically Digested Slurry as N Sources for Grass Forage Production

We conducted a 3-year field study to determine how raw dairy slurry and anaerobically digested slurry (dairy slurry and food waste) applied via broadcast and subsurface deposition to reed canarygrass (Phalaris arundinacea) affected forage biomass, N uptake, apparent nitrogen recovery (ANR), and soil nitrate concentrations relative to urea. Annual N applications ranged from 600 kg N ha−1in 2009 to 300 g N ha−1in 2011. Forage yield and N uptake were similar across slurry treatments. Soil nitrate concentrations were greatest at the beginning of the fall leaching season, and did not differ among slurry treatments or application methods. Urea-fertilized plots had the highest soil nitrate concentrations but did not consistently have greatest forage biomass. ANR for the slurry treatments ranged from 35 to 70% when calculations were based on ammonium-N concentration, compared with 31 to 65% for urea. Slurry ANR calculated on a total N basis was lower (15 to 40%) due to lower availability of the organic N in the slurries. No consistent differences in soil microbial biomass or other biological indicators were observed. Anaerobically digested slurry supported equal forage production and similar N use efficiency when compared to raw dairy slurry.