Soil remediation application for a sustainable environment

Undisclosed industrial client India Soil Remediation

An industrial client in India faced soil contamination from the over-usage of mercury, with a government remediation standard set at 20mg/kg of mercury concentration in soil. CFlo designed a compact, customised ex-situ wet processing plant that scrubs, screens and washes contaminated soil, reuses 95% of its water, and returns clean fractions for use as construction material or backfill.

The Challenge

Soil contamination from industrial activity, agricultural chemicals and improper waste disposal carries significant health risks through direct contact, contaminant vapours and secondary contamination of water supplies. The Central Pollution Control Board's Comprehensive Environmental Pollution Index identified 43 critically polluted zones across 16 states with CEPI ratings above 70, 21 of them in Gujarat, Uttar Pradesh, Maharashtra and Tamil Nadu.

At this site, mercury over-usage had contaminated the soil, and the government set a remediation standard of 20mg/kg before granting permission for work to commence. The client also had a severe space limitation, making it a challenge to install remediation equipment of the required scale.

The Solution

CFlo specialises in ex-situ remediation, cleaning brownfield and contaminated soils through a mechanical treatment process designed for the level and type of contamination. Tests at CFlo's DSIR-accredited lab showed the contamination was carried by soil sticking to the material's surface. The scope was to thoroughly scrub, screen and wash all fractions to liberate the stuck soil and capture the contaminated water.

The patented system includes the Scrubmax Heavy-duty Scrubbing System, which liberates sticky soil through extensive attrition, followed by final wet screening with pressurised water and dual-stage Hydrocyclone technology to segregate particles into size fractions. The isolated screened soil of typically -75 microns, along with process water, is collected in a Decanter solid-water separation system: water is recovered for recirculation while the fine soil is stocked under cover for mercury recovery through Retort processing. Despite the space constraint, CFlo designed a compact layout and successfully installed and commissioned the plant.

20mg/kg

government mercury remediation standard met

95%

of water reused by the plant with minimum spillage

-75 micron

contaminated fraction isolated for mercury recovery

The Results

The washed fractions are free from contamination and ready for reuse as construction material or for restoring previously contaminated excavated ground, while cleaned soil provides a sustainable source of backfill for contractors.

More proof