Application of flocculated sewage sludge for growing miscanthus on post-mining lands.

Abstract

Miscanthus yields well on raw subsoil where organic matter and nutrients are supplied by sewage sludge; the yield is directly dependent on the amount of sludge applied; the greatest productivity (12.9t/ha) was achieved by adding 60t/ha of flocculated sludge. Among the macronutrients, nitrogen is most actively absorbed, the intensity of biomass accumulation of phosphorus and potassium is much lower; other essential elements can be ranked as Fe → Zn → Mn → Cu. Cobalt, nickel and cadmium do not accumulate in biomass but chromium does. The introduction of sewage sludge affects the thermal characteristics of the miscanthus biomass. The proportion of incombustible residue increases when sludge is applied at high doses. Application of 20t/ha flocculated sludge appears to be optimal for ensuring environmental safety and suitability as a fuel.