Abstract
Wastewater contains resources, which can be recovered for secondary use if treated properly. Besides research in zero liquid discharge solutions, the aim of the study was a simultaneous recovery of products from a wastewater treatment plant’s dewatering liquor. To be specific, we investigated a simultaneous recovery of struvite and irrigation water using electrodialysis (ED) in laboratory experiments. Two products were obtained from ED—concentrate and diluate. The concentrate was precipitated to obtain struvite. On average, 11 g of wet precipitate (including 17.58% of dry solids) were obtained from 1 L of concentrate. Crystal phases were confirmed by powder X-ray diffraction (XRD), with showing 94–97% recovery of struvite, while the remaining 3–6% were identified as hazenite. The average yield of crystal struvite was 1.76 g. Both struvite and hazenite may further be used as a fertilizer. Next, we suggest using the second ED product, the diluate, as irrigation water if it meets the irrigation water requirements. Attention was paid to the concentrations of dissolved solids (DS) in diluate, which decreased by an average of 93% compared to the input values in the dewatering liquor. In line with the observed Czech or EU standards indicators, we can say that the diluate can be used in agriculture, namely as irrigation water (Category I—water suitable for irrigation).
Highlights
Published: 19 November 2021The world population is growing, and sustainable and responsible food production is important to ensure sufficient food supplies
Note: Conductivity was measured by WTW GmBH Multi340i, WTW, Prague, Czech Republic
Using atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) we identified the concentrations of selected heavy metals in the input wastewater, the obtained diluate, and the concentrate
Summary
The world population is growing, and sustainable and responsible food production is important to ensure sufficient food supplies. One of the requirements for proper plant growth is a sufficient amount of phosphorus [1] which is mainly obtained by mining phosphorus rock. As much as 80% of total phosphorus is subsequently used to produce fertilizers for agriculture [2], making phosphorus an irreplaceable component of this sector. Natural phosphorus reserves are depleting, and their quality is falling [3]. The available reserves of phosphorus rock are estimated to last only another. The availability of phosphorus rock may be influenced by political, economic, and geographic situations in the site of the rock deposit [4,6]. Already in 2014, the mineral resource of phosphorus was identified as critical by the European
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