Recovery of phosphate and ammonia from wastewater via struvite precipitation using spent refractory brick gravel from steel industry
Journal
Journal of Environmental Management
Journal Volume
302
Date Issued
2022
Author(s)
Abstract
Spent refractory brick (SRB) generated from the steel industry has a high magnesium content. In this study, a procedure was developed to utilize SRB gravels for efficient recovery of phosphate and ammonia from high strength wastewater via struvite (MgNH4PO4?6H2O(s)) precipitation. Mg2+ and Ca2+ were first leached from SRB gravels using nitric acid solution. Ca2+ in the solution could inhibit struvite precipitation and was sequestered by dosing SO32? to form calcium sulfite (CaSO3(s)). The resulting Mg2+-rich solution was then employed to initiate struvite precipitation for phosphate and ammonia recovery. The optimal precipitation was achieved with a molar ratio of [Mg2+]:[NH3–N]:[PO43–P] = 2:1:2 at pH 9.5. The residual phosphate in the solution can be further removed via the precipitation of calcium phosphate minerals. Overall, 99.6% phosphate and 98.2% ammonia could be recovered and the treated wastewater could meet the discharging standards of ammonia and phosphate. The resulting solids, including calcium sulfite, struvite and calcium phosphate can be potentially used in the cement industry and agriculture sector to achieve sustainable recycle of spent materials. ? 2021 Elsevier Ltd
Subjects
Calcium
Circular economy
Magnesium
Nutrients
Resource recycle
aluminum
ammonia
calcium
calcium ion
calcium phosphate
iron
magnesium ion
manganese
nitric acid
phosphate
sodium ion
struvite
sulfate
sulfite
steel
iron and steel industry
precipitation (chemistry)
wastewater
wastewater treatment
Article
chemical composition
compressive strength
cost benefit analysis
effluent standard
energy dispersive X ray spectroscopy
environmental parameters
furnace
leaching
pH
precipitation
scanning electron microscopy
solution and solubility
spent refractory brick gravel
waste component removal
waste water management
water supply
X ray diffraction
sewage
Ammonia
Chemical Precipitation
Phosphates
Steel
Struvite
Waste Disposal, Fluid
Waste Water
Type
journal article