Linear and Non-linear Regression Analysis for the Adsorption Kinetics of SO2 in a Fixed Carbon Bed Reactor – A Case Study

Kinetic parameters of SO2 adsorption on unburned carbons from lignite fly ash and activated carbons based on hard coal dust were determined. The model studies were performed using the linear and non-linear regression method for the following models: pseudo first and second-order, intraparticle diffusion, and chemisorption on a heterogeneous surface. The quality of the fitting of a given model to empirical data was assessed based on: R2, R, Δq, SSE, ARE, χ2, HYBRID, MPSD, EABS, and SNE. It was clearly shown that it is the linear regression that more accurately reflects the behaviour of the adsorption system, which is consistent with the first-order kinetic reaction – for activated carbons (SO2+Ar) or chemisorption on a heterogeneous surface – for unburned carbons (SO2+Ar and SO2+Ar+H2O(g)+O2) and activated carbons (SO2+Ar+H2O(g)+O2). Importantly, usually, each of the approaches (linear/non-linear) indicated a different mechanism of the studied phenomenon. A certain universality of the χ2 and HYBRID functions has been proved, the minimization of which repeatedly led to the lowest SNE values for the indicated models. Fitting data by any of the non-linear equations based on the R or R2 functions only, cannot be treated as evidence/prerequisite of the existence of a given adsorption mechanism.

Integrated Use of Co-Compost with Lignite Fly Ash on Yield and Nutrient Uptake of Certain Crops

A field experiment was conducted to know the response of crops to combined application of co compost and lignite fly ash. Field experiments were conducted in experimental farm (rice and maize) and farmers holding (groundnut and brinjal) to study the response of certain crops to the application of co composts and lignite fly ash grown in clay loam and sandy clay loam soil, respectively. The treatment consisted of Dairy Farm Waste + Crop Residues, Pressmud+ Crop Residues, Dairy Farm Waste + Crop Residues + LFA @5 t ha-1, Dairy Farm Waste + Crop Residues + LFA @10 t ha-1, Dairy Farm Waste + Crop Residues + LFA @15 t ha-1, Pressmud + crop residues + LFA @5 t ha-1, Pressmud + crop residues + LFA @10 t ha-1and Pressmud + crop residues + LFA @15 t ha-1 .The grain and straw yield in rice and maize, pod and haulm yield in groundnut and fruit yield of brinjal were recorded during harvest. Differences in yield of crops between the treatments indicate significantly different effects on soil fertility and crop yield after long-term fertilization. The uptake of nutrients increased linearly with levels of LFA tried and it was higher when it was applied with co compost of pressmud and crop residue. The addition of co composts alone or with graded dose of lignite fly ash significantly improved the physical properties of the soil.

Co-disposal of lignite fly ash and coal mine waste rock for neutralisation of AMD

Waste rocks (WRs) from a lignite-producing coalfield and fly ash (FA) produced from the same lignite have been investigated in this study with a primary objective to determine the potential for co-disposal of WRs and FA to reduce the environmental contamination. Mixing WRs with FA and covering WRs with FA have been investigated. Particle size effect caused ≤2 mm particles to produce low pH (~2) and metal-laden leachates, indicating higher sulphide minerals’ reactivity compared to larger particles (≤10 mm, pH ~ 4). Co-disposal of FA as mixture showed an instantaneous effect, resulting in higher pH (~3–6) and better leachate quality. However, acidity produced by secondary mineralisation caused stabilisation of pH at around 4.5–5. In contrast, the pH of the leachates from the cover method gradually increased from strongly acidic (pH ~ 2) to mildly acidic (pH ~ 4–5) and circumneutral (pH ~ 7) along with a decrease in EC and elemental leaching. Gradually increasing pH can be attributed to the cover effect, which reduces the oxygen diffusion, thus sulphide oxidation. FA cover achieved the pH necessary for secondary mineralisation during the leaching experiment. The co-disposal of FA as cover and/or mixture possesses the potential for neutralisation and/or slowing down AMD and improving leachate quality.

Investigation of Environmental Leaching Behavior of an Innovative Method for Landfilling of Waste Incineration Air Pollution Control Residues

Waste incineration air pollution control (APC) residues require pretreatment before landfilling because these types of residues encompass pollutants from an incineration gas stream. The environmental concerns of APC residues consist of a risk of leaching and subsequent release of potentially harmful substances that occur under environmental exposure. The stabilization/solidification (S/S) method of incineration residues is one of the most applied technologies for hazardous incineration residues. Portland cement is commonly used as a binder material in S/S for pollutant encapsulation, in order to change the hydrological characteristics of the landfilled material. Based on previous research, an innovative S/S method for APC residues is investigated, meant to replace Portland cement with cement-like material made from lignite fly ash (FA). To do this, a lab-scale landfill was created through the promoted S/S method and exposed to the environment for 12 months. Thus, this article assesses the lab-scale leaching behavior of a landfill disposal material exposed to environmental conditions and attempts to prove the promoted innovative S/S method. The results show that the replacement of Portland cement with a substitute material for utilization in the S/S method can mitigate energy consumption in the industrial cement subsector.