Production of slow release crystal fertilizer from wastewaters through struvite crystallization – A review

Recovery of Struvite from Synthetic Animal Wastewater by Continuous Reaction Crystallization Process

“…Recovery of phosphate(V) ions from animal breeding wastewater is a complex process, difficult in practical implementation [2], [3], mainly because of its chemical composition. Main problem is high nitrogen, potassium and calcium contents, similar to phosphorus content [4], as well as presence of other impurities (especially: zinc, manganese, boron, copper and iron). These can catalyse or inhibit nucleation of struvite, calcium phosphates(V) and other sparingly soluble salts or/and hydroxides, as well as influence further nuclei growth, thus product quality [5].…”

“…Presence of calcium ions in a process system results that the product is a mixture of struvite and calcium phosphates(V) [8]. It essentially restricts its possible application as a mineral fertilizer [9].The research results concerning continuous struvite reaction crystallization process from synthetic animal breeding wastewater (SABW), of chemical composition similar to liquid cattle manure, are compared [1], [4]. Concentration of phosphate(V) ions in this solution was 0.208 mass %.…”

Recovery of Struvite from Phosphorus Mineral Fertilizer Industry Wastewater in Continuous Jet Pump Crystallizer

“…Besides crucial for environmental protection effect of wastewater purification (eutrophisation prevention), separated crystal product is regarded as an important, secondary phosphorus source. Recovered struvite can be further conversed or used directly as mineral fertilizer for agriculture [3], [4].…”

“…Process runs under precisely determined and controlled hydrodynamic conditions, inside an appropriately designed crystallizer [3]. Besides crucial for environmental protection effect of wastewater purification (eutrophisation prevention), separated crystal product is regarded as an important, secondary phosphorus source.…”

“…Besides crucial for environmental protection effect of wastewater purification (eutrophisation prevention), separated crystal product is regarded as an important, secondary phosphorus source. Recovered struvite can be further conversed or used directly as mineral fertilizer for agriculture [3], [4].Efficiencies of struvite nucleation and mass crystallization processes are strongly dependent on crystallizer, including: appropriate construction [5], spatial arrangement of reagent inlet places [6] and proper selection of its continuous work parameters [7], [8]. In most DTM (Draft Tube Magma) type crystallizers adjustment of working supersaturation can be achieved by arrangement of controlled internal circulation of suspension inside the apparatus [9].…”