Ferric nitrate was used to provide iron source, and Fe?C₃N₄ composite material was prepared by impregnation method. FT?IR was used to characterize and analyze the prepared materials. The results show that Fe doping does not change the skeleton structure of g?C₃N₄ and can increase the photocatalytic performance of g?C₃N₄ materials. Taking orange II as the target pollutant, Fe?C₃N₄ catalyzed the activation of persulfate to degrade azo dyes under visible light. The effects of persulfate dosage, Fe?C₃N₄ dosage, pollutant concentration and pH conditions on the degradation effect were examined, and the reaction kinetics was studied to analyze the stability of the prepared catalytic materials. The results show that when the Fe?C₃N₄ concentration is 2.0 g/L, the molar ratio of persulfate to pollutants is 1 200∶1, and pH=3, the degradation effect is best, and the degradation rate is 77.8%; Fe?C₃N₄/persulfate system is dual the degradation of nitrogen dyes satisfies the quasi?second?order kinetic equation; Fe?C₃N₄ material is reusable.

Using sludge from municipal sewage treatment plants as raw materials, sodium bicarbonate as green activator, and ammonium phosphate as nitrogen and phosphorus source, modified sludge biochar was prepared by vacuum pyrolysis. SEM and FT?IR were used to characterize and analyze the materials. The results show that the modified sludge biochar can significantly increase the specific surface area and porosity of the biochar, as well as the number of N-H and C-O. By changing the dosage of modified sludge biochar, pollutant mass concentration, reaction temperature and pH value and other conditions, the effect of modified sludge biochar on phenol adsorption was studied, and the adsorption process and mechanism were studied. The results show that the modified sludge biochar has a better adsorption effect on phenols, and the adsorption rate increases with the increase in the dosage of sludge biochar; when the pollutant mass concentration increases, the adsorption rate decreases; the higher the temperature, the better the adsorption effect; the acidic conditions are more suitable for the reaction. The adsorption process of modified sludge biochar for phenols conforms to quasi?second?order kinetics, and the adsorption mechanisms are monolayer adsorption and uneven surface adsorption. Modified sludge biochar has good recyclability and it can provide an effective way for the resource utilization of sludge and the treatment of phenols in wastewater.

Petroleum resin wastewater sludge is classified as hazardous waste. The method of sludge recycling was introduced through the analysis of the main components of sludge, and the adsorption conditions and effects of phosphorus were studied. The results show that the main components of petroleum resin wastewater sludge are petroleum pollutants such as benzene, naphthalene, indene, azulene, olefins, alkanes and so on . After calcined at 600 ℃, the weight reduction of sludge was 82.5%, and an adsorption material based on γ?Al₂O₃ was obtained. The optimal adsorption conditions of calcined sludge for phosphorus: Adsorption time is 90 min, oscillation intensity is 180 r/min, pH=4, initial phosphorus concentration is 12.5 mg/L and dosage of sludge is 2.0 g. The optimal adsorption removal rate of phosphorus is 93.8%, and the adsorption removal rate after circulation is 87.0%. Therefore, after the calcination treatment of petroleum resin wastewater sludge, the reduction and recycling of hazardous waste can be successfully achieved.