The Central Pollution Control Board (CPCB) has issued new guidelines for the management and utilization of slurry generated from marble and granite processing units. This action follows a directive from the National Green Tribunal (NGT) aimed at preventing the unscientific dumping of this waste, which has been linked to the contamination of water, soil, and air.
The guidelines, which are applicable to all existing and new processing units, address the scale of the problem. Rajasthan alone, a major hub for marble processing, generates an estimated 5 to 6 million tonnes of slurry annually. The CPCB’s framework is based on extensive studies and consultations with leading research bodies such as CSIR-Central Road Research Institute (CRRI) and the Central Building Research Institute (CBRI).
Key Requirements for Storage and Transportation
The new rules mandate that processing units must make specific provisions to prevent unregulated dumping:
All units must arrange for temporary slurry storage in areas lined with impervious materials like concrete or HDPE to prevent seepage into the soil and groundwater.
Dedicated slurry transportation vehicles must be equipped with GPS tracking systems to monitor their movement and prevent illegal dumping. These vehicles must also be properly covered to prevent spillage and dust emissions.
Transforming Waste into a Resource: Utilization Options
The core of the new guidelines focuses on converting the slurry into a valuable resource. Several applications have been identified, with different uses for marble and granite slurry based on their unique chemical compositions.
Options for Marble Slurry (High in Calcium Carbonate)
Marble slurry can be used to replace up to 15% of limestone in the manufacturing of Ordinary Portland Cement (OPC).
Studies by CSIR-CRRI have shown that a mixture of 20-35% marble slurry with soil is suitable for constructing sub-grade layers in road pavements.
The slurry can be used for manufacturing flooring and wall tiles, bricks, precast concrete, and paver blocks.
It can be utilized as a low-cost binder, a filler material in mineral grinding, or even for producing lime, poultry feed ingredients, and artifacts.
Options for Granite Slurry (High in Silica and Alumina)
Granite slurry can be used in the development of fly ash-based geo-polymeric concrete for making road components, paving blocks, and curb stones.
Patented technology exists for using granite slurry to create high-performance composite wood for furniture and building construction.
Regulatory and Monitoring Mechanism
To ensure compliance, all marble and granite processing units are now required to submit a comprehensive slurry utilization plan to their respective State Pollution Control Board (SPCB) or Pollution Control Committee (PCC) as a mandatory condition for obtaining or renewing their Consent to Operate (CTO).
Furthermore, SPCBs/PCCs are directed to develop a new online portal to create a centralized database of slurry generation and utilization. This portal will serve as a tool for monitoring production volumes, quality parameters, and the mapping of all dumping sites, ensuring transparency and accountability