Surface Complexation Modeling for the Stabilization of an Industrial Sludge by Alternate Materials

Abstract

The main aim of this paper is to model the behavior of a mixture of 30% fly ash, 60% black cotton soil, 30% heavy metal laced industrial sludge and 15% cement for sorption of chromium and copper at different pH values. It was found that the mixture of 30% fly ash, 60% soil, 30% sludge and 15% cement was the ideal combination found from extensive leaching experiments, for heavy metals such as Cr +6 and Cu 2+ . Owing to practical difficulties in carrying out leaching tests over wide range of pH values, Visual minteq was used to simulate these conditions. It is found that the model predicts the retention behavior accurately and was further confirmed with the output of experimental work done earlier. A series of visual minteq simulations revealed that surface complexation and reduction play an important role in the sorption process. It was concluded that the hazardous sludge laced with heavy metals can be stabilized. The study would benefit the design engineers in understanding and in finding alternate means for treating industrial sludge wastes.

Retention Studies on Arsenic From Aqueous Solutions by Lime Treated Semi Arid Soils

“…This slurry was agitated with a mechanical shaker at room temperature (25±2°C) for 2 h until the pH was stabilized. The pH of the slurry was adjusted to the desired value in the range of 2 to 10 with 0.1M HNO3 and NaOH [27][28][29].…”

Efficacy of nano calcium silicate (NCS) treatment on tropical soils in encapsulating heavy metal ions: leaching studies validation

“…This increased the efficacy of NCS as a stabilizing material for long-term attenuation requirements of the industry. Further, to validate the use of NCS as a soil amendment, many more leaching tests have been performed under various conditions [17,18,21]. It was found that because of the organic nature of BCS and being an expansive soil with low strength parameters, it was decided to continue further tests only with red soil.…”

Vertical distribution of heavy metals in seawater column during IBA construction in land reclamation – Re-exploration of a large-scale field trial experiment

“…Re-adsorption usually happens under, 1) the presence of competitive ions; 2) the presence of extra precipitates induced by change of ambient geochemistry (e.g. pH); and 3) the presence of complexation surface (Moghal et al, 2014;Qiu et al, 2018;Wang et al, 2009). As seawater were extremely abundant surrounding IBA in all designated experiments, the competitive ions (born from IBA) would be greatly diluted (Yang et al, 2016) while seawater significantly buffers the changes of environmental chemistry in the solution induced from IBA (Cyronak et al, 2018;Fajar et al, 2015;Hain et al, 2015).…”