Integrated biological treatment of fowl manure for nitrogen recovery and reuse

Biowaste such as animal manure poses an environmental threat, due to among others, uncontrolled emissions of ammonia and additional hazardous gases to the atmosphere. This study presents a quantitative analysis of an alternative biowaste management approach aimed at nitrogen recovery and reduction of contamination risks. The suggested technology combines anaerobic digestion of nitrogen-rich biowaste with biofiltration of the resulting gaseous ammonia. A compost-based biofilter is used to capture the ammonia and convert it to nitrate by nitrifying microorganisms. Nitrogen mass balance was applied to quantify the system's capacity under various fowl manure-loading regimes and ammonia loading rates. The produced nitrate was recovered and its use as liquid fertilizer was evaluated with cucumber plant as a model crop. In addition, emissions of other hazardous gases (N2O, CH4 and H2S) were monitored before and after biofiltration to evaluate the efficiency of the system for treating these gases. It was found that nitrate-rich liquid fertilizer can be continuously produced using the suggested approach, with an over 67 percentage of nitrogen recovery, under an ammonia loading rate of up to 40 g NH3 per cubic meter biofilter per hour. Complete elimination of NH3, H2S, CH4 and N2O was achieved, demonstrating the potential of the suggested technology for mitigating emission of these gases from fowl manure. Moreover, the quality of the recovered fertilizer was demonstrated by higher yield performance of cucumber plant compared with control plants treated with a commonly applied organic liquid fertilizer.

► Biowaste management scheme to reduce potential pollution from manure was verified.
► The biofilter (LOFPS) completely eliminated NH3, H2S, CH4 and N2O emission.
► High recovery (>67%) of manure N in the fertilizer, mainly as NO3−, was achieved.
► Efficacy of the N-rich fertilizer was demonstrated by high yield of cucumber.