A novel process to recycle the highly concentrated calcium and chloride ions in the gelatin acidification wastewater

The effluents of the gelatin acidification process are highly complex and difficult to treat, especially in the presence of high concentrations of Cl−, which not only pollute the environment, but also seriously hamper the development of bone gelatin enterprises. In this study, a novel cleaner production process for recycling the highly concentrated calcium and chloride ions is proposed to basically solve the problem of acidification wastewater management in the gelatin industry. In this process, wastewater from the acidification process is firstly reacted with sulfuric acid to generate calcium sulfate and then the effluent is further treated by distillation. The outcomes demonstrate that the concentration and recycling rate of hydrochloric acid in the distillate could reach close to 6.1% and 75% under the optimal conditions, and the recycled hydrochloric acid could be reused in the acidification process. Meanwhile, the emission of wastewater could be reduced about 70%. The purity (98%) and composition (calcium sulfate hemihydrate) of the calcium sulfate were explored by X-ray photoelectron spectrometer and X-ray diffraction. The output of CSH was 75 kg per tonne of wastewater (11.5T per tonne of gelatin). Additionally, analyzing the operational cost of this process shows that about the operational costs could be halved. In conclusion, this novel process minimizes the wastewater discharge and achieves the cleaner production in gelatin industry.