Fly Ash Utilization Benefits Assessed

The question asks to identify fly ash utilization methods with future ecofriendly and economic benefits. Let's analyze each method:

Method (I) Direct Application to Cropland

• Ecofriendly Concerns: Fly ash can contain heavy metals (e.g., arsenic, lead, mercury) and other compounds. Direct application might lead to soil contamination, potentially harming soil ecosystems and entering the food chain, raising ecofriendly questions.
• Economic Viability: While seemingly low-cost, long-term soil health degradation or the need for remediation could negate economic benefits.

Method (II) Converting to Bricks

• Ecofriendly Advantages: Utilizes industrial waste, reducing landfill burden. Fly ash bricks often require less firing energy compared to traditional clay bricks, lowering carbon emissions. They also conserve topsoil which is needed for clay extraction.
• Economic Advantages: Reduced manufacturing costs due to less energy consumption and the use of readily available waste material. These bricks are durable and cost-effective construction materials.

Method (III) Using as Road-Sub-base Material

• Ecofriendly Advantages: Replaces mined aggregates (like gravel and crushed stone), conserving natural resources. Reduces the volume of fly ash going to landfills.
• Economic Advantages: Often less expensive than traditional aggregates. Its properties can provide good load-bearing capacity for roads, contributing to infrastructure cost-effectiveness.

Conclusion on Benefits

Methods (II) Converting to Bricks and (III) Using as a road-sub-base material offer clear future ecofriendly and economic advantages by conserving resources, reducing waste, lowering energy consumption, and providing cost-effective materials compared to direct application on croplands which poses environmental risks.

Therefore, the correct option includes (II) and (III) only.