Solidification/Stabilization of Textile Sludge as Subgrade: Usage of Binders and Skeleton Material

Xiao Cheng,Shihu Gao,Geng Chen,Bingyi Li

doi:10.1155/2020/8873098

Abstract

This study investigates the disposal of textile sludge via laboratory and field tests while protecting the eco-environment. Solidification/stabilization (S/S) technology and skeleton construction method are introduced to investigate the application of S/S sludge for subgrade material. S/S is to enhance the sludge strength and stabilize the metal(loid)s and hazardous organics in the textile sludge. Skeleton construction method aims to decrease the liquid-solid ratio in mixture to reduce the binder dosage and save binder cost. In the laboratory, binders and skeleton material are implemented to investigate the differences in unconfined compressive strength (UCS) to explore the optimal mixture. Results illustrate that UCS of binder-sludge is below 100 kPa and enhanced more than 400 kPa after adding gypsum and skeleton material. Skeleton soil material with high plasticity index and low moisture content improves UCS significantly. Scanning electron microscopy test shows the physical microstructure of sludge is greatly improved for the particular space grid structure formed by the particles and cementitious products. The leaching test shows the metal(loid)s and organics in leachate are decreased after S/S treatment and below the standard value. Finally, the textile sludge was disposed for subgrade via the technology. The strength and leaching results of field tests are in good agreement with the laboratory results. The bearing capacity of the practical subgrade meets the design requirements.

Highlights

As the demand of textile products increases, textile wastewater derived from the textile industry constitutes a large proportion of the industrial wastewater around the world.e textile wastewater was disposed by biochemical and physical methods, resulting in a lot of textile sludge over time [1]
Samples of textile sludge below a depth of 0.2 m were collected by an excavator after removal of bare surface sludge. e samples were filled into sealed containers and preserved in the dark (25 ± 5°C in temperature and more than 80% in humidity) to prevent dehydration and decomposition. e surface of the samples is black-yellow, while the interior is black (Figures 1(a) and 1(b)). e physical properties of the sludge are presented in Table 1. e moisture content was determined by the oven drying method with a temperature of 65–70°C, since the organic matter content is above 5% [30]
In this study, a huge amount of water (ω > 500%) causes few solid particles in the textile sludge. ere are not enough solid particles in per unit volume to satisfy the cementation of hydration products. e cementation from cement cannot be compared with the reduction of water content and cementation from quicklime

Summary

Introduction

As the demand of textile products increases, textile wastewater derived from the textile industry constitutes a large proportion of the industrial wastewater around the world.e textile wastewater was disposed by biochemical and physical methods, resulting in a lot of textile sludge over time [1]. E sludge accumulated by occupying land could cause land waste and trigger ecoenvironmental problems. Textile sludge has a complex constitution, containing organic pollutants and heavy metals. It is highly contaminative and harmful for both public health and environment [3]. Considering these characteristics, a lack of safe disposal of textile sludge will lead to severe secondary pollution of the environment. Erefore, a scientific and economic disposal of the textile sludge becomes a worldwide problem. Solidification/stabilization (S/S) technology is an effective, economic feasibile, and environmental protection sludge disposal method [4]. In situ S/S technology has been applied to large-scale engineering, such as soft foundation treatment and contaminated soil disposal [5, 6]

Methods

Results

Conclusion