Study Area: The SAF leather industry is situated at Noapara in Abhaynagar Upazila of Jashore district figure the effluent as collected from this industry site. t is located between and North latitudes and in between and East longitudes. It is bounded by Jashore Sadar and Narail Sadar Upazila on the North, Khan Jahan Ali Thana, Damuria and Phultala Upazila of Khulna District on the South, Narail Sadar and Kalia Upazila on the East, Jashore Sadar and Manirampur Upazila on the West.
Preparation of Tea residue: The tea (Camellia sinensis) residue was collected from the nearby tea stall of Ambattalla Bazaar, Jashore on 30 April 2017. The residue was washed with tap water first and then with distilled water for several times until a colored component and other soluble dirtiness were removed. After washing, the residues were filtered and were dried in an electric oven at 55°C for 48 hours and then air dried for another 24 hours. After that the residues was grinded with the electric blender and were sieved (150-mesh size). The fine residues were preserved in an airless container so that they could not react with the neighboring environment.
Preparation of Orange Peel: Oranges (Citrus sinensis) were collected from a local market Barobazar, Jashore on 30 April, 2017. Then the oranges were washed with tap water first and then with distilled water and air-dried. After that, the peels were removed with clean hands and were sun-dried for 4 days. The dried peels were grinded with the help of electric blender till fine size. The fine peels were sieved (150-mesh size) and then preserved in small clean plastic jar, so that the peels could not react with the neighboring environment.
Preparation of Charcoal: Homemade charcoals were collected from Ambattalla, a Bazaar of Jashore District on 2 May, 2017. The charcoal was prepared by burning the dried young branch of Mahogany (Mahogany; Swietenia mahagoni). The charcoal was washed with tap water first and then with distilled water properly. After air drying, the charcoal was crushed in the particular size (150-mesh) with hammer in a clean sealed cloth bag. The particular size charcoal was preserved in airless container, so that charcoal could not react with the neighboring environment.
Effluent Collected from SAF Leather Industry: The effluent was collected from the source point of the leather industry. Plastic bottles were collected and shocked in 0.1 N HCl for overnight and then rinsed with distilled water about 3 to 4 times. Before sampling, the bottles were rinsed with sample water 2 or 3 times, so that the sample could represent the total characteristics of polluted water. After sampling, the bottles were tightened properly with sealed cap to avoid air bubbles. The samples were labeled properly showing the location name, date and time of sample collection and were preserved immediately in refrigerator at 4°C. The sampling time was between 4.00 pm - 4.30 pm on 9 May, 2017. The SAF leather industry releases its polluted effluent directly into the Bhairab river at around 4.00 pm every day.
Place of Experiment and Analysis: The experiment was set up in the Environmental Chemistry Laboratory, Department of Environmental Science and Technology, Jashore University of Science and Technology, Jashore 7408, Bangladesh. The color, odor, electrical conductivity (EC), total dissolved solids (TDS), nitrate (NO3 -) and phosphate (PO4 3-) were determined in our Laboratory. The heavy metals Fe, Mn, Cu, Pb and Cr were determined by atomic absorption spectroscopy (AAS; Loeppert and Inskeep, 2001) in the Laboratory of Asia Arsenic Network, Jashore 7400. This study was conducted during the period of April, 2017 - May, 2017.
Experimental Design: The volume of the sterilized plastic bottle was 500 mL. In each bottle, 250 mL effluent and 5.0 g bio-adsorbent of each (tea residue, orange peel and charcoal) were taken. There were 12 bottles [3 (control) + 3 (for 3 days) + 3 (for 6 days) + 3 (for 9 days) for each bio-adsorbent. Therefore, the total numbers of bottles were 12 × 3 = 36 for 3 types of bio-adsorbent. All these bottles were places carefully in the safe place and investigated for days’ time period. The bottles were shaken carefully (by hand) and almost similarly for mixing up the adsorbents with effluents.
Statistical Analysis: The experiment was arranged in randomized blocks with three replications in the Laboratory. The data were subjected to statistical analysis of variance (ANOVA) with Student-NeumanKeuls multiple-range test and the means were tested using Duncan's Multiple Range est MR at % level of significance.