دانلود رایگان مقاله انگلیسی شکل گیری استروویت از فاضلاب کشاورزی و استفاده مجدد از آنها در زمین کشاورزی - الزویر 2019

ABSTRACT

To meet the needs of a fast growing global population, agriculture and livestock production have been intensified, resulting in environmental pollution, climate change, and soil health declining. Closing the nutrient circular loop is one of the most important sustainability factors that affect these issues. Apart from being a serious environmental issue, the discharge of N and P via agricultural wastewater is also a major factor that disturbs nutrient cycling in agriculture. In this study, the performance, in terms of recovery, of N and P (individually, as well as simultaneously) from agricultural wastewaters via struvite has been comparatively summarized. Details on the hindrances to nutrient recovery through struvite formation from agricultural effluents, along with strategies to overcome these hindrances, are provided. In addition, various strategies for recovery performance intensification and operational cost reduction are comprehensively discussed. This work will provide scientists and engineers with a better idea on how to solve the bottlenecks of this technique and integrate it successfully into their treatment systems, which will ultimately help close the nutrient loop in agriculture.

Conclusions

Struvite crystallization is an effective and eco-friendly technique that coverts nutrients from wastewater into a valuable resource. Various factors, including the suspended solids, and calcium, phosphorus and heavy metals concentrations, hinder the closure of nutrient cycles in the agriculture sector by struvite precipitation. Application of low-cost sources of Mg and P can improve the economics of this method. Likewise, the adoption of pH-increasing strategies, such as air stripping along with base (NaOH) application, can further reduce costs. The most effective and economical method is to reproduce Mg and P compounds by recycling struvite, using techniques like pyrogenation, ultrasound stripping, and electrolysis. The effect of struvite fertilizers on nutrient uptake and crop yields has been reported; nevertheless contradictory results exist. Although struvite has good potential for nutrient recovery from various agricultural wastewaters, future research on its utilization as a fertilizer, especially for major crops under various field conditions, is still needed.