Adsorption of chromium (Cr) from tannery wastewater using low-cost spent tea leaves adsorbent

Md Nur-E-Alam,Md Mafizur Rahman,Farid Ahmad,Md Abu Sayid Mia

doi:10.1007/s13201-018-0774-y

Abstract

Leather tanning is consuming a large quantity of water and discharging a large volume of wastewater. This wastewater contains the high value of COD, BOD, TSS, TDS and heavy metals. In this study, spent tea leaves, a valueless waste produced during the manufacturing of tea beverage, were assessed for their potential to remove chromium (Cr) from tannery wastewater. Cr removal was studied by the batch process with varying adsorbent dose, contact time and pH of the solution to finding optimum conditions. The experiment results showed that maximum removal of Cr by spent tea leaves was 95.42% at 14 g/L of adsorbent dose and pH 10. The maximum adsorption capacity of Cr on tea waste was found 10.64 mg/g.

Highlights

Tanning is a process of converting putrescible outer coverings of animals to non-putrescible leathers with definite physical, chemical and biological properties so that they can be used in our daily life and industries (Dutta 1999)
The percentage of Cr removal is seen to increase with adsorbent dose up to 14 g/L for the samples (S1, S2 and S3)
Spent tea leaves are a cheap and available material discarded as waste material from teashops to hotels in the environment without any treatment can be converted into valuable product as adsorbent for chromium (Cr) removal from tannery wastewater

Summary

Introduction

Tanning is a process of converting putrescible outer coverings of animals to non-putrescible leathers with definite physical, chemical and biological properties so that they can be used in our daily life and industries (Dutta 1999). In Bangladesh, the leather industry is well established and ranked fourth in terms of earning foreign exchange. This sector includes 220 tanneries, 3500 SMEs and 110 large. Among the toxic heavy metals, chromium, in its hexavalent form, it is known to cause wide-ranging human health effects including mutagenic and carcinogenic risks (Park and Jung 2001). Chromium is used in leather tanning, dye and pigment manufacturing, the making of wood preservatives and so on. Chromium is an essential element involved in the normal metabolism of carbohydrate and lipid in humans. High level of Cr content was found in the surface water of Hazaribagh tanning area (939.81 mg/L) (Nur-E-Alam et al 2017)

Methods

Results

Conclusion