Effect of additives on the properties of ceramsite from solid wastes

The main purpose of this study is to investigate the properties of ceramsite from solid wastes, with glass cullet and corn stalk as additives, and its adsorption performance of NH₄⁺–N in water was studied. The results showed that the physical properties of the ceramsite met with the China’s industrial standard as the artificial ceramsite filter material for water treatment (CJ/T 299-2008) when the specific formula of dewatered sewage sludge, river sediment, and coal fly ash were in mass ratio of 5:4:1, and the dosages of glass cullet and corn stalk were 7.0 and 9.0 g per 100 g mixture, respectively. The concentration of heavy metals in the lixivium was also lower than the threshold of China’s national standard for hazardous wastes (GB 5085.3-2007). Meanwhile, the 3-order polynomial model could be used to describe the sintering process, with the critical temperature was 500 °C. The adsorption results indicated that the equilibrium adsorption capacity of the ceramsite was 1.83 mg/g when the initial concentration of NH₄⁺–N, reaction temperature and adsorbent dosage were 75 mg/L, 298 K, and 10 g/L, respectively. Freundlich isotherm was more suitable for describing the adsorption process and this process was in conformity with pseudo-first-order kinetics.