In Turkey, the commercial laundry wastewater is usually discharged to the receiving water bodies and its reuse potential is ignored. This wastewater is grouped into the greywater due to their content of organic and inorganic pollutants. In recent years, the sequential processes have become more preferable in greywater treatment and reuse. In this study, a batch adsorption process was applied for further treatment of commercial laundry wastewater which is also pre-treated by means of the electrocoagulation process. In adsorption, two different composites of waste hazelnut shell derived activated carbons, which are supported with polyaniline (PAn/HS) and polypyrrole (PPy/HS), were used as adsorbents. The efficiency of the process was evaluated by means of an experimental design, and the response surface methodology was applied for this purpose. In the experiment with PAn/HS, the chemical oxygen demand (COD) 75% removal efficiency was accomplished with adsorbent dosage of 0.9 g, at pH 8, with 125 rpm mixing rate and for 77.5 min reaction time. For PPy/HS under the same experimental conditions, the COD removal efficiency was obtained as 20%. The utilization of waste hazelnut shell derived composites as adsorbents for commercial laundry wastewater treatment is a good alternative. The production costs of adsorbents were estimated as 0.70 USD/g and 3.21 USD/g for PAn/HS and PPy/HS, respectively. In terms of the production cost, the PAn/HS composite is approved more agreeable as adsorbents for commercial laundry wastewater treatment.
BACKGROUND:In Turkey, which is one of the world's top walnut producers, the volume of waste shell has increased in recent years as a result of escalating consumption. Globally, including in Turkey, cleaning products are the leading pollutants entering the aquatic environment. This study aimed to address both issues, by investigating the removal of Linear Alkyl Benzene Sulphonic Acid synthetic solution through a fixed-bed adsorption column system embedded with the composite of a polyanilinesupported activated walnut shell. RESULTS: Linear Alkyl Benzene Sulfonic Acid removal efficiency was evaluated in terms of detergent and chemical oxygen demand (COD) parameters. Column performance increased with low flow rate, increased bed height and high inlet concentration. Optimum conditions were determined as 7.5 cm bed height, 10 mL min −1 flow rate, and 30 mg L −1 inlet solution concentration. Thomas and Yoon-Nelson models were applied to experimental data to estimate the column adsorption behavior. The Yoon-Nelson model (R 2 > 0.9) seemed fit to explain the adsorption column behavior. To understand the reuse capacity of the adsorbent a regeneration study was carried out, showing that the maximum adsorption capacity of the adsorbent (q total ) decreased from 216 mg g −1 before regeneration to 6.4 mg g −1 after the third regeneration cycle. CONCLUSION: This adsorbent has a high potential for detergent and COD adsorption from anionic aqueous solutions, and would be a good alternative for a pretreatment step.
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