Background of the Study

Huge physiological, histological, hematological, behavioral, genetic, biochemical, and immunological alterations in aquatic organisms have been reported due to Cr exposure. Remediation of toxic industrial effluents is very important for the protection of the environment.

The quality of these effluents is most commonly monitored by analyzing major pollution parameters such as pH, electrical conductivity (EC), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), total dissolved solids (TDS), total suspended solids (TSS), and metals.

Tannery wastewater may contaminate water bodies in Bangladesh in a number of ways. Discharge of untreated or partially treated wastewater into the rivers or canals is one method. This can take place if the treatment facilities are insufficient or poorly maintained. It might affect the environment and the general public’s health.

Untreated wastewater may include a range of dangerous elements, such as bacteria, viruses, minerals, and chemicals, that might be damaging to both human health and the environment. 

Contamination of surface and groundwater sources, such as rivers, lakes etc might be a consequence of untreated tannery wastewater. These water bodies can get contaminated when wastewater is dumped into the environment, making them unfit for human use and posing harm to aquatic life.

Problem Statement:

Tannery Industries use various chemicals for leather production and wastewater released by the tannery industries can be a source of toxic chemicals. Tannery wastewater is a major environmental concern due to its high content of toxic pollutants such as heavy metals, organic compounds, and salts. 

The recently constructed Savar tannery industrial estate may lead to soil, water, and plants contamination around that area. The discharge of untreated tannery wastewater into water bodies can lead to severe environmental and public health issues. Many studies have focused on bioremediation and phytoremediation strategies for treating tannery wastewater.

But it is not well observed that which species among Eichhornia crassipes, Pistia stratiotes, Clarias batrachus, Anabas testudineus can improve the quality of tannery waste water more efficiently. Moreover, there is limited findings about at which concentration, the species worked their best.

Research Gap: 

There are few comparative studies on the efficiency of Eichhornia crassipes, Pistia stratiotes and fish species Clarias batrachus, Anabas testudineus in the remediation of tannery wastewater. Most previous studies have focused on the use of a single fish species or different fish species without comparing their efficiency. Moreover, there is limited findings about at which concentration, the species worked their best. 

Therefore, this study aims to address this research gap by comparing the efficiency of Eichhornia crassipes, Pistia stratiotes and fish species Clarias batrachus, Anabas testudineus in improving the quality of tannery wastewater and also at which concentration, the species worked best.

Research Questions: 

• Among Eichhornia crassipes, Pistia stratiotes and fish species Clarias batrachus, Anabas testudineus which species worked most efficiently in improving tannery wastewater quality? 
• At which wastewater concentration did the species perform best? 

Research Objectives: 

• To determine the ideal wastewater concentration for Eichhornia crassipes, Pistia stratiotes and fish species Clarias batrachus, Anabas testudineus in improving tannery wastewater quality. 

• To find out the best species among all in improving tannery wastewater quality.