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Ammonium is a water pollutant that harms the environment, particularly fisheries. Rice straw is also an economic waste of rice, with millions of tons produced per year around the world. In this paper, physical and chemical procedures for the modification of rice straw were studied. The kinetic and isothermal adsorption trends were investigated, including the ammonium removal efficiency, the contact time of the adsorbent, the amount of adsorbent, and the initial concentration of NH 4 þ . The effect of temperature and pH on the adsorption process was discussed. The removal efficiency of NH 4 þ recorded 43, 53.7, and 69.5%, with maximum adsorption values of 2.9, 3.5, and 4.5 mg/g at temperatures of 25 AE 5, 35 AE 5, and 45 AE 5 C, respectively, at pH 7.5. The biochar obtained from rice follows the pseudo-second-order equation for ammonium adsorption kinetics (R 2 ¼ 0.98). The adsorption isotherm follows Freundlich's model (R 2 ¼ 0.99) and Langmuir's model (R 2 ¼ 0.98).

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Aerobic biological treatment of waters in artificial conditions is carried out by symbiotic algobacterial community of attached and free-floating organisms in various types of aerotank and biofilters. With the blowers and mixers of different designs, the biomass is saturated with oxygen. Controlled air supply provides the necessary concentration of dissolved oxygen and stimulates the oxidation of organic and inorganic water pollutants symbiotic community.