A new approach to developing a remediation plan for soil contaminated with industrial waste
M.A. Shumilova, V.G. Petrov
Section: Remediation and rehabilitation
After what happened in August 2018 the spill of caustic industrial waste on the agricultural lands of the Alnash district of Udmurtia, we were tasked with the prompt remediation of the affected farmland. A group of environmental and resource-saving technologies carried out regular sampling of four soil samples, including the control one from a conditionally clean soil, before the start of work and after technological measures for a long period.
Analysis of the water extract of contaminated soil samples a month after the spill showed a high acidity of the waste: pH = 1.546 ÷ 2.186. The content of nitrates in the soil was determined by a photometric method; however, the acid trapped in the soil oxidized the iron(II) ions to iron(III); therefore, the formation of its complex of bright purple color makes further determination of nitrates problematic. The addition of a 5% sodium carbonate solution to the original soil filtrate at a ratio of 2: 1 caused the formation of a precipitate of iron(III) hydroxide, which was filtered off and then worked according to the procedure. According to the experimental data, nitrates in the contaminated soil did not exceed the values of the background sample.
The quantitative determination of chloride ions in the soil was carried out by argentometric method, preliminarily precipitating iron(III) with a sodium carbonate solution. The excess of the chloride content in the contaminated soil compared to the background was from 113 to 213 times. A method for remediation of contaminated soil was developed at the experimental stand. Carrying out the proposed measures made it possible to reduce the amount of pollutants in the affected soil to background values.
To exclude the ingress of hazardous industrial waste into the environment it is required to create specialized enterprises for their neutralization and disposal.