Ammonium Fertilizers Production from Manure: A Critical Review

Abstract

Excessive livestock production in small areas poses a risk of nitrogen release to the environment and thus air and water contamination. Recovery of ammonia is necessary to avoid overfertilization, but manure management of untreated slurry is costly and complex. The authors discuss ammonium fertilizer recovery from manure using membrane processes and physicochemical methods including technology and energy assessments. Currently, nanofiltration, reverse osmosis, membrane distillation combined with ultrafiltration, and air stripping are the best choices. The processes rely highly on selection of appropriate pretreatment, as residual particulates will lead to fouling of membranes and stripping towers hence affect the performance greatly.

Recovery of nutrients from biogas digestate with biochar and clinoptilolite

“…Emission of ammonia, nitrous oxide (N2O) and malodorous gases may occur which cause unpleasant odours during storage and after field application (Feilberg & Sommer, 2013;Velthof et al, 2015). In addition to odour problems, use of digestate may contribute to soil pollution via deposition of ammonia and nitrogen oxides (Zarebska et al, 2015).…”

“…Transportation of digestate to wider application areas is necessary to prevent overloading of the receiving land with nutrients in excess of crop demand. Management and utilisation of the untreated or liquid fraction of digestate presents a challenge in areas with very high animal densities or no cropping land suitable for digestate fertilisation (Zarebska et al, 2015).…”

“…The liquid fraction also has a potential value as a fertiliser due to its contents of dissolved nutrients. However the high water content of the liquid fraction of digestate means that it is relatively expensive to store and transport (Zarebska et al, 2015). It is therefore desirable to develop methods that can be used to concentrate or remove the nutrients from the liquid fraction.…”

“…Further concentration of these nutrients in the liquid fraction could reduce transportation costs and potentially increase the fertiliser efficiency of the liquid fraction of manure and digestate. Concentration techniques using water evaporation and ammonia stripping consume a great deal of energy and are usually rather costly (Christensen et al, 2013;Fuchs & Drosg, 2013;Zarebska et al, 2015). Treatment of digestate using an ion exchanger/adsorptive agent may therefore present an attractive alternative.…”

“…Moreover, environmental problems such as gaseous emissions of malodors, ammonia and greenhouse gases as well as nutrient runoff to streams and waterways may occur when digestate is applied to agricultural land (Hjorth et al, 2009). Processing of manure and digestate may potentially overcome practical and environmental problems related to their direct application on land by reducing their environmental impacts, and improve the fertilising efficiency of manure and digestate (Fuchs & Drosg, 2013;Zarebska et al, 2015).…”