BIOCHAR ABSORBS HEAVY METALS FROM THE COMPOSTS AT THE BEGINNING OF THE COMPOSTING PROCESS

Abstract

Chicken manure is a source of biogenic elements and therefore can be used as a nonconventional fertilizer after composting. However, chicken manure can contain different hazardous substances including antibiotic resistant bacteria and corresponding genes of antibiotic resistance that can be transmitted to human and livestock trough soils and plants even after composting. Besides chicken manure composts can contain heavy metals that not only harm soils and yields directly but also stimulate the process of antibiotic resistance genes transfer and therethrough harm soils and plant consumers indirectly. The purpose of the present study was to reveal the potential of the chicken manure biochar, the type of biochar that is not fully studied yet, as a tool to reduce the level of available heavy metals content in the chicken manure composts. For this purpose, chicken manure was composted with straw (control), and with addition of heavy metals mixture (M) as well as with addition of those with 15% chicken manure biochar (BM). Ni, Fe, Cd and Cu were added to the compost mixtures M and BM to reach concentrations of 70, 1500, 130, and 1000 mg/kg, respectively. Composting lasted for 120 days, in all three cases � C, M and BM - the thermophilic stage phase lasted from days 2 to 5, and the temperature values were 44-53 ?�. It was found that chicken manure biochar is an effective way to reduce the content of available forms of Cd, Fe and Ni at the early stages of composting and reduces the concentration of those metals by 47, 17 and 45 % on the first day, respectively.