Development of biochar from the refuse derived fuel (RDF) through organic / inorganic sludge mixed with rice straw and coconut shell

Highlights: • Mixed sludge increases the C% after adding rice straw and coconut shell. • Water content is one of the important factors affecting the productivity of sludge. • Carbonization of coconut shell shows optimal at 350 °C than other material. • The calorific value of the raw materials detected in the study shows to be maximum at 350 °C. • The highest calorific value of the Organic and Inorganic sludge was 1199 and 434 Cal/g. With the advancement of technology and industrial growth, environmental pollution has become the major phenomenon that hinder the environmental adjoining with the volume of wastes that has been discarded without any proper treatment. In particular, industrial sector consumes a maximum amount of water which results in generating of large quantity of solid waste-sludge. However, with the progression of environmental awareness, the treatment of sludge recycling and reuse has been carried out considerably. Subsequently, after drying, sorting, granulating, sintering and other procedures, it is re-created into various types of aggregates and used for making biochar and other purposes. Therefore, in this study, the waste rice straw and coconut shell were mixed with the sludge and the biomass was pressed to form a non-loose granular shape, subjected to low-temperature of 300–400 °C co-firing carbonization technique for 30–60 min to prepare a solid refuse-derived fuel (RDF-5). The higher the addition ratio of the raw material (rice straw or coconut shell), the more superior is the effect of the mixture. The optimum carbon content is then mixed with inorganic sludge (IS) and organic sludge (OS) and the calorific value obtained was about 2852 Cal/g and 2840 Cal/g.