Nutrient Removal from Treated Effluent of a 3 MLD Sewage Treatment Plant Using Biochar Adsorbent in Fixed Bed Column

Abstract

Our study aims for the green synthesis of an effective biochar adsorbent from Agro-waste to remove additional nutrients such as nitrogen and phosphorus from the treated effluent of 3MLD SBR STP at IIT Roorkee campus. The biochar adsorbent was successfully synthesized via single-step from agricultural waste i.e., sugarcane bagasse by pyrolysis process in presence of nitrogen gas at 550℃ for 30 min, 45 min, 1 hr., and 1 hr. 15 min. The material was further characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDX), and X-ray powder diffraction (XRD). For the optimization of removal of additional nutrients, four experimental columns made of borosilicate glass with an internal diameter of 30 mm and a length of 250 mm. All 04 columns were packed with the different adsorbent materials (35 mm) varying in preparation time viz. 30 min., 45 min., 1 hr., and 1 hr. 15 min. respectively between the supporting layers of glass wool (10 mm) each (for improving the flow distribution and prevention of the loss of adsorbent), and gravel (105mm and 90 mm). The Peristaltic pump was used to draw water from the inlet water can to the column. The up-flow mode was used to prevent channeling and assure consistent streaming. Columns of diameter 3.0cm and length 25.0cm were fabricated with four different materials (varying in their preparation time). The effect of initial adsorbate concentration, and the flow rate of adsorbate in the column were studied for the optimization of the adsorption column setup. Initially, there was an increase in the pH of the adsorbate by 3% for almost one week indicating the release of alkali ions from the adsorbent. The maximum bed capacity was obtained at the lowest flowrate and a highest initial concentration. The experimental data were fitted with different models such as the Thomas, Yoon-Nelson and, Adam-Bohart models. Both Thomas and Yoon-Nelson models were found to show a good agreement with the experimental data as compared to Adam-Bohart model.