Abstract
Abstract This article focuses on developing a methodology which can be used to estimate the concentration of dyestuff released from textiles during domestic laundering, so that further studies involving decolorization of the wastewater from domestic washing machine can be conducted in an attempt to develop eco-friendly domestic washing processes. Due to the complexity of the problem, an approach was adopted so that, as an initial step, synthetic red and blue reactive dye solutions were prepared as representative wastewater solutions using Reactive Red 195 and Reactive Blue 19 dyestuffs for the estimation of dye concentration. This was followed by an experimental work consisting of washing tests involving the calculation of dye concentration in the wastewater obtained from domestic washing machine as well as tergotometer as a machine simulator. For this part of the work, dyed cotton plain jersey fabric samples were used to obtain wastewater solutions. All the dye solutions and the wastewater samples were measured with VIS spectrophotometer, and the maximum absorbance values were obtained at relevant wavelengths. Although the characteristics of absorbance spectra of synthetic and wastewater solutions were very different, the maximum absorbance values of both solutions overlapped at relevant wavelengths. The concentration of the dyestuff was calculated from the absorbance values measured at 540 and 592 nm for the red and blue, respectively. The statistical analysis of the data suggested that tergotometer can be used as a domestic washing machine simulator. Moreover, the regression analysis done for the dyestuff concentration under discussion revealed that the most significant factor was the washing step (main wash or rinsing) (89.5%) followed by color (red or blue) (3.4%) and washing device (washing machine or tergotometer) (1.5%).
Highlights
There is a potential for gray water reuse in the developing regions of the world
For Step 1, the wavelength giving the maximum absorbance value from the absorption spectrum was found at 540 nm for the Red dye solution and 592 nm for the Blue dye solution, which complies with the literature survey [15, 16, 38,39,40,41]
The study discussed in this article focused on developing a methodology to estimate the dye concentration in chaotic wastewater obtained from the domestic machine laundering of dyed textiles
Summary
There is a potential for gray water reuse in the developing regions of the world. Gray water is defined as wastewater generated from domestic activities, such as dish washing, laundry, and bathing. The advantage of recycling gray water is that it is a large source with low organic content; it contains significant concentrations of materials with potential negative environmental and health impacts, such as salts, surfactants, oils, synthetic chemicals, and microbial contaminants [1]. Reusable gray water should fulfill four criteria: hygienic safety, aesthetics, environmental tolerance, and technical and economic feasibility [2]. Different reuse applications require different water quality specifications, demanding different treatments varying from a simple coarse filtration to an advanced biological treatment [3]. It was reported that, besides conventional techniques used to remove various pollutants, there are some advanced techniques which have been proven to be more eco-friendly, rapid, and cost- and time-effective in nature [4]
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