Polysilicate-ferric-calcium-lanthanum (PSFCL) was synthesized through a co-polymerization method in order to treat the yellow phosphorus wastewater. Its morphology, composition and functional group were analyzed by X-ray Diffraction (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Scanning Electron Microscopic (SEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The optimization of the flocculant was also investigated, including La/Si molar ratio, pH, agitation time, dosage and sedimentation time. Results showed that PSFCL has reached an excellent removal efficiency of 95% and 97% towards phosphorus and fluoride, respectively. It could be inferred that charge neutralization, bridging effect and ligand exchange were the main coagulation mechanisms. As a whole, after the introduction of lanthanum, PSFCL was found to be a promising flocculant in yellow phosphorus wastewater treatment owing to its high removal efficiency and simple synthesis route.
With the rapid development of agriculture, controlling phosphorus emissions is a pressing challenge for preventing water eutrophication . A graphite-promoted cyclopentane (CP) hydrate-based desalination was proposed to remove K 3 PO 4 from effluents. It was found via the in situ optical microscopy that the reaction temperature and the concentration of feeding K 3 PO 4 solution significantly affect the morphologies and amount of the as-produced CP hydrate crystals. The lower reaction temperature produces more crystals with irregular shapes, while fewer crystals formed in K 3 PO 4 solution with higher concentration. The reaction temperature, time and feeding concentration-dependent desalination and salt enrichment performances were studied. It was found that desalination efficiency linearly increases with the elevated reaction temperature ranging from − 2 °C to 3 °C; however, water recovery declines with temperature. The temperature-dependent water recovery is due to the strong driving force for hydrate formation at low temperatures. The time-dependent water recovery shows a three-stage feature, including exponential growth, linear increase, and stable stages, owing to the interaction between the driving force of supercooling and the increasing K 3 PO 4 concentration during the reaction processes. The desalination efficiency shows an inverted volcanic shape with the increased concentration of feeding K 3 PO 4 solution. The pre-melting effect plays a critical role in improving desalination efficiency at high K 3 PO 4 concentrations. A maximum desalination efficiency of 85.0% was reached for treating an artificial solution with salinity as high as 42452 mg/L. Both desalted water and concentrated phosphorus-containing solution can be recovered by this method, which is attractive for producing freshwater with potential for recovery of resources.
Qiang Li,Song Wang,Lifang Wang,Li Zhang,Xiaohui Wan,Zhiguo Sun
Phosphorus recovery from industrial wastewater has attracted considerable interest. In this study, struvite crystallization method has been used for treatment of high phosphorus wastewater. The new combination agents of Mg5(CO3)4(OH)2·4H2O and NH4Cl were used as the precipitant. The effects of initial pH, n(Mg):n(P), n(N):n(P), and reaction time on the removal of total phosphorus (TP) in wastewater were investigated. The results showed that under the condition of initial pH = 4, Mg:N:P = 1.2:1.1:1, reaction time for 30 min, and static storage for 20 min, the residual amount of TP in wastewater was 2.98 mg /L, and the removal rate of TP reached 99.99%. The mass fraction of P2O5in the generated sediment reached 25.22%, equivalent to high grade phosphate ore and slow-release fertilizer, so as to realize the recycling and utilization of phosphorus in ultra-high phosphorous wastewater. This work will have practical application potential in treatment of high phosphorus wastewater and environmental management.Keywords:struvite crystallization method;environmental management;ultra-high phosphorus wastewater;basic magnesium carbonate;phosphorus recovery
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