Pre-processing of dry waste fraction (paper, plastic, textile, leather, wood) into Refuse-Derived Fuel (RDF) — pellets, fluff, briquettes — for use in cement kilns, dedicated waste-to-energy plants, or industrial boilers. RDF specification, calorific value, contamination limits, integration with MRF, financial viability, role in waste diversion from landfill.
Refuse-Derived Fuel (RDF) is the dry-waste counterpart to composting + biomethanation. While those handle the biodegradable fraction, RDF processes the combustible dry fraction — paper, plastic, textile, leather, wood — that doesn't compost.
The process: source-segregated dry waste enters pre-processing (shredder → magnetic separator removes ferrous → eddy-current separator removes non-ferrous → drying → density separator removes inerts → pelletiser/baler creates uniform fuel). Output: 10-50 mm pellets (or fluff < 100 mm) with calorific value 12-18 MJ/kg, suitable for substitution of coal in cement kilns or dedicated WTE plants.
Why cement kilns: they're the ideal destruction environment. 1450-2000 °C combustion temperature destroys all organics + dioxins; 4-7 second residence time ensures complete combustion; alkaline atmosphere neutralises HCl + SO2 emissions; ash becomes part of clinker (no separate ash disposal). The Indian cement industry uses ~10-15 % alternative fuel currently, with a 30 % Thermal Substitution Rate target by 2030 — massive demand-side pull.
The economics work: ULBs pay cement plants ₹500-2000/tonne tipping fee (vs ₹500-1500/tonne landfill cost). Cement plants save ₹1500-3500/tonne by displacing coal (which costs ₹4500-7000/tonne, with calorific value 25 MJ/kg vs 15 for RDF). Net win for both parties.
Top Indian co-processors: UltraTech, ACC, Ambuja, Shree Cement, Dalmia, JK Cement — most have multiple plants accepting RDF from cities within ~200 km radius. Project economics depend on this transport distance.
Specification matters: cement kilns are picky. Chlorine ≤ 0.7-1.0 % (chloride embrittles kiln equipment + corrodes preheaters), moisture ≤ 20 % (degrades calorific value + adds heat-up energy), ash ≤ 15-20 %, LCV ≥ 14 MJ/kg. RDF not meeting spec gets rejected — wasted production cost.
Pre-processing capex: ₹10-25 crore per 50 TPD throughput. Yields 10-15 TPD RDF at 15-25 % conversion ratio.
Critical warning: RDF must NOT be combusted in uncontrolled boilers (small industries, brick kilns). Without proper flue gas scrubbing, dioxin + heavy metal emissions are dangerous. CPCB norms apply only to approved installations — cement kilns + dedicated WTE plants with emission control. Strictly prohibited otherwise.
Storage: covered + sealed to prevent moisture re-absorption (degrades CV), dust generation, + spontaneous combustion risk (especially in monsoon humidity).
Where this chapter sits: RDF + cement co-processing handle the dry-combustible fraction (~15-25 % of MSW) that wouldn't otherwise be recycled or composted. Combined with composting + biomethanation (50-60 %) + recycling via MRF (15-20 %), this leaves 5-15 % residue for landfill (chapter 9). The RDF route is increasingly the preferred alternative to dedicated WTE plants (chapter 8) due to better economics + lower technology risk.