ABSTRACT Nitrogen (N) can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate) has the highest N content in ammonia form (NH3). It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ) and to mitigate NH3 emissions during N land application. Additional benefit is to minimize inhibition of the anaerobic process by removing NH3 during the anaerobic digestion process. This work aimed to apply the gas-permeable membrane technology to evaluate ammonia (NH3) recovery from high-ammonia digested swine manure. Anaerobically digested swine manure with NH4+ content of 4,293 mg N L−1 was reduced by 91 % (to 381 mg N L−1) during the 32-day experiment. Although the results showed a total N recovery efficiency of 71 %, it is possible to increase this recovery efficiency to > 90 % by adjusting the area of the membrane system to match the high free ammonia concentration (FA) in digested swine manure. Moreover, final digestate pH and alkalinity were kept around 8.1 and 8,923 mgCaCO3 L−1, which are convenient for the anaerobic process or incorporation in arable soil when the process is finished.

ABSTRACT Land application of both anaerobic lagoon liquid and sludge can increase nutrient accumulation beyond the soil’s 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 the 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 the dissolution of P from sludge into the overlying lagoon liquid. On the other hand, the removal of solids by both pretreatments effectively reduced Cu and Zn concentrations in the lagoon liquid, and 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 the reduction of input solids can help minimize both the frequency of sludge removal for lagoon maintenance and the land area for its disposal.

The present study aimed to describe the bacterial community present at an anaerobic up flow bioreactor with ANAMMOX activity, inoculated with the sludge from the anaerobic pond of a swine slurry treatment system. The description was based on the molecular DNA techniques using primers for amplification of complete 16S rRNA gene and also new primers to amplify smaller fragments from 16S rRNA. During the bioreactor operation time, the bacterial community changed significantly, increasing the nitrogen removal efficiency, reaching after 500 days a removal rate of 94%. The complete PCR amplification of 16S rRNA gene generated 17 clones, where three presented similarity with Candidatus Jettenia asiatica (97%), twelve with Janthinobacterium (99%) and two with uncultured clones. The PCR amplification of 436 base pairs had generated 12 clones, of which eight presented 96-100% similarity with Candidatus Anammoxoglobus propionicus, Planctomycete KSU-1 and one with Pseudomonas sp. (99%) and three with uncultured clones.