Water environment effect of soil modification by solid waste from phosphorus chemical industry

With the rapid growth of the phosphorus chemical industry， the accompanying generation of phosphogypsum and phosphorous tailings presents significant environmental challenges. These materials are industrial by-products produced during phosphorus processing and characterized by their large volumes and low resource utilization rates. Addressing how to effectively and safely utilize these waste materials is critical for the sustainable development of phosphorus chemical enterprises. This paper focused on artificial land creation in severely degraded and desertified areas where these materials generally cannot be employed. We investigated the impact of different land reclamation methods on water quality indicators， including total nitrogen （TN）， total phosphorus （TP）， fluoride （F-）， and heavy metals such as lead （Pb）， cadmium （Cd）， and arsenic （As），to evaluate the potential for environmental pollution resulting from these treatments. The findings revealed that modified phosphogypsum treatment was the most effective in reducing TN and TP concentrations， surpassing the results obtained from phosphorous tailings. Furthermore， the layered processing technique proved to be more advantageous than the integrated approach， suggesting that stratification of materials can enhance the treatment efficacy. In terms of fluoride concentrations， modified phosphogypsum consistently showed higher levels than those treated with phosphorous tailings； however， the fluoride levels from phosphorous tailings met the Surface Water Environmental Standard， and Class I of Groundwater Environmental Standard（≤1 mg/L）. When examining heavy metal concentrations， all levels from modified phosphogypsum treatments remained below the Class IV surface water quality standards and Class III groundwater quality thresholds， indicating a relatively lower risk of environmental contamination. Risk assessments further illustrated that the modified phosphogypsum treatment posed no pollution risk， while treatments involving phosphorous tailings led to minor pollution concerns. In stark contrast， the control samples exhibited moderate pollution with elevated pollution indices. By developing and implementing effective methods for reclaiming and utilizing phosphogypsum and phosphorous tailings， we can contribute to more sustainable practices in the phosphorus chemical sector. The successful application of modified phosphogypsum and phosphorous tailings for land creation could serve as a model for similar initiatives in other sectors generating significant industrial waste.