Nitrogen transfer from grey municipal solid waste to high quality compost

Ammonia was transferred from an anaerobically digested mixed waste at high pH (due to addition of 10% CaO) to an actively nitrifying, high quality mature vegetable–fruit–garden compost. After 5 days indirect contact with the anaerobic compost, by laying a sieve in-between the two materials, the recipient aerobic compost exhibited a rapid increase in NH4+–N concentration, followed by a subsequent decrease due to nitrification. The nitrifying activity (ammonium oxidation rate) was 94 mg NO2−-N/kg DW•d in the treated aerobic compost. In the non-treated aerobic compost, the activity was 22 mg NO2−-N/kg DW•d. The treated aerobic compost contained 967 mg NO3−-N/kg DW. In the control aerobic compost, the amount was 291 mg NO3−-N/kg-DW. The treated aerobic compost can serve as a readily available N source to ensure rapid crop development. This methodology increases the agricultural value of the compost for areas where industrial fertilisers may not be advisable or available.