Sustainable Use of Sludge from Industrial Park Wastewater Treatment Plants in Manufacturing Lightweight Aggregates.

Chao-Wei Tang,Chiu-Kuei Cheng

doi:10.3390/ma15051785

Abstract

The aim of this study was to investigate the development of a process for manufacturing lightweight aggregates (LWAs) by incorporating sludge from wastewater treatment plants in industrial parks with reservoir sediments. The research was divided into two stages: laboratory-scale firing and large-scale firing. In the laboratory-scale stage, a high-temperature furnace was used for trial firing. In the large-scale stage, a commercial rotary kiln was used for trial firing for mass production. The test results showed that the water absorption, dry loose bulk density, and crushing strength of the sintered LWAs were 14.2–26.9%, 634–753 kg/m3, and 1.29–2.90 MPa, respectively. Moreover, the water absorption of the sintered LWAs increased as the percentage of added sludge increased. In addition, the dry loose bulk density of the sintered LWAs gradually decreased as the percentage of added sludge increased. Moreover, the results of the heavy metal toxicity characteristic leaching procedure (TCLP) dissolution test for the LWAs produced by blending 30–50% sludge were all lower than the standard value required by the Taiwan Environmental Protection Agency for general industrial waste. The strength grade of the sintered LWAs was 20 MPa. From this point of view, the sintered LWAs that were studied under the test conditions could be used as aggregates for lightweight concrete and would allow it to have a reasonable strength of greater than 20 MPa.

Highlights

Publisher’s Note: MDPI stays neutralIn an effort to develop the national economy, the total number of industrial parks established in Taiwan reached 70 by 2019
Affairs of Taiwan set up 39 wastewater treatment plants to ensure that the wastewater that is discharged from factories in these industrial parks complies with Taiwan’s water pollution prevention and control regulations
In terms of the effect of the soaking time during the preheating phase respectively. These results show that the designed experimental formulations are suitableon the particle density of the lightweight aggregates (LWAs), under the same formula and firing conditions, the longer the for LWA firing

Summary

Introduction

In an effort to develop the national economy, the total number of industrial parks established in Taiwan reached 70 by 2019. Affairs of Taiwan set up 39 wastewater treatment plants to ensure that the wastewater that is discharged from factories in these industrial parks complies with Taiwan’s water pollution prevention and control regulations. After solving the problem of wastewater discharge in these industrial parks, a large amount of industrial wastewater sludge is produced, with an output of about 600,000 tons per year, forming a new waste treatment problem [1]. Due to a variety of problems, such as difficult land acquisition and energy consumption, the disposal of waste sludge in industrial parks via landfills or incineration is not in line with current environmental goals, and it is not conducive to the construction of a recycling society. Wastewater sludge contains a large number of inorganic substances, such as calcium, silicon, aluminum, iron, and other with regard to jurisdictional claims in published maps and institutional affiliations

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Conclusion