Abstract
Textile wastewater from wet processing units is a major environmental problem. Most chemicals, including dyes, are only partly consumed, resulting in highly colored wastewater containing a variety of chemicals released into the environment. This paper gives information on the current management of textile wastewater in Tanzania. A semiquantitative analysis was done to identify the main types of chemicals used in wet processing units, wastewater characteristics and existing wastewater treatment methods in the textile industry. The performance evaluation of the existing wastewater treatment plants is also discussed. The advantages of integrating constructed wetlands with the existing treatment facilities for textile wastewater are explained. It has been observed that pretreatment and dying/printing of the fabrics are the main two processes that produce wastewater in many textile companies. Main pollutants are chemicals used from pretreatment and materials removed from de-sizing, bleaching and scouring processes. Dyes, printing pigments and dye auxiliaries are the main pollutants from the dyeing/printing process. Most of the textile companies in Tanzania are equipped with effluent treatment plants. Wastewater treatment plants have basically similar units, which are coagulation-flocculation, sedimentation through clarifiers and aerobic reactor. However, their effluents do not meet discharge limits stipulated by the Tanzania Bureau of Standards (TBS).
Highlights
Textile industries generate huge quantities of wastewater with complex chemical substances from different processing units as unused materials (Dasgupta et al )
The first was a pretreatment step which included sizing and de-sizing, scouring, bleaching and mercerization processes. Pollutants from these steps were the chemicals used in these steps and the materials or waste from fabrics removed by those processes
The chemicals used in dyeing and printing processes were dyes, dye pigments and dyeing auxiliaries
Summary
Textile industries generate huge quantities of wastewater with complex chemical substances from different processing units as unused materials (Dasgupta et al ). Some of the companies do not have a wastewater treatment plant and discharge untreated wastewater into the environment. The discharged untreated wastewater causes undesirable changes to the environment, affecting its ecological status (Verma et al ). M. Bidu et al | Textile wastewater management in Tanzania
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