To reduce the suspended solids load to a trickling filter installation, raw swine effluent was pre-treated with ferric chloride and a cationically charged polyacrylamide coagulant resulting in unexpected struvite accumulation downstream of this post-separation process. Using this pre-treated swine manure, struvite precipitation studies were carried out as a function of pH at laboratory and pilot batch and continuously operated scales. An optimal reaction time of 30 min was established for struvite precipitation in the pre-treated swine wastewater at pH 8.5, minimizing the co-precipitation of interfering minerals. Ferric chloride addition resulted in magnesium solubilization, such that no external additional source of magnesium was required for struvite formation. Aeration alone did not result in significant pH increases, so base addition was required for pH adjustment. X-ray diffraction revealed that the only crystalline phase produced was struvite. Removal of phosphate and ammonium attained 98% and 17% respectively in laboratory scale experiments. At the pilot-scale, removal attained 99% and 15% of phosphate and ammonium in both batch and continuously HRT = 1h) operated reactors.
"chemical engineering research and design x x x ( 2 0 1 2 ) xxx–xxx address phosphorus removal by water professionals (Gonzalez and De Sa, 2007). MAP crystallization has been applied for several purposes, such as to prevent scaling problems (Doyle and Parsons, 2004) and to remove phosphate (Battistoni et al., 1997) or nitrogen (Laridi et al., 2005). Recent publications show an increasing interest in struvite precipitation as a technology for phosphorus recovery taking into account the economic impact of increasing energy costs and limited natural phosphorus resources (Carballa et al., 2008; Forrest et al., 2008). "
[Show abstract][Hide abstract] ABSTRACT: On the basis of the perspective of wastes recycling and minimization of cost of phosphate removal via the chemical precipitation procedure, the present studies evaluated the ability of waste biogenic Gastropod shell to serve as a source of Ca2+ ion in the removal and recovery of phosphate in calcium phosphate mineral (CPM) crystallization procedure. Phosphate removal efficiency values >99% was achieved when 2 g of snail shell was used in water of phosphate concentrations ranging between 25 and 1000 mg/L. pH and ionic strength exhibited no influence on the phosphate removal efficiency. Concomitant removal of phosphate and organic matter revealed that phosphate removal efficiency was not impacted but the magnitude of the organics removed increased with increase in the organic load. Kinetic analysis showed that second order kinetic model gave a better description of the process. XRD analysis of the derived sludge showed the crystallinity and peaks synonymous with the presence of whitlockite, hydroxyapatite and calcium phosphate hydrate. The FTIR of the sludge showed the disappearance of some naturally occurring functional groups and the appearance of phosphate peaks which confirmed the formation of CPM.
Chemical Engineering Research and Design 05/2013; 91(5):810–818. DOI:10.1016/j.cherd.2012.09.017 · 2.28 Impact Factor
"Nutrient removal by struvite (MgNH 4 PO 4 · 6H 2 O) or magnesium ammonium phosphate (MAP) precipitation is an interesting alternative approach to address phosphorus removal (von Munch and Barr, 2001; Gonzalez and De Sa, 2007). MAPc rystallisation can be applied for several purposes, such as to prevent scalingp roblems (Doyle and Parsons, 2004) and to remove phosphate (Battistoni et al.,1 997) or nitrogen(Altinbas et al.,2002; Laridi et al.,2005). Recent publications show an increasing interest in struvite precipitation as at echnology for phosphorus recovery taking into account the economic impact of increasing energy costsand limited natural phosphorus resources (Durrant et al.,1 999; Shu et al.,2 006; Carballa et al.,2 008; Forrest et al.,2 008). "
[Show abstract][Hide abstract] ABSTRACT: Pilot-scale struvite crystallization tests using anaerobic effluent from potato processing industries were performed at three different plants. Two plants (P1 & P2) showed high phosphate removal efficiencies, 89+/-3% and 75+/-8%, resulting in final effluent levels of 12+/-3 mg PO(4)(3-)-PL(-1) and 11+/-3mg PO(4)(3-)-PL(-1), respectively. In contrast, poor phosphate removal (19+/-8%) was obtained at the third location (P3). Further investigations at P3 showed the negative effect of high Ca(2+)/PO(4)(3-)-P molar ratio (ca. 1.25+/-0.11) on struvite formation. A full-scale struvite plant treating anaerobic effluent from a dairy industry showed the same Ca(2+) interference. A shift in the influent Ca(2+)/PO(4)(3-)-P molar ratio from 2.69 to 1.36 resulted in average total phosphorus removal of 78+/-7%, corresponding with effluent levels of 14+/-4 mg P(total)L(-1) (9+/-3 mg PO(4)(3-)-PL(-1)). Under these conditions high quality spherical struvite crystals of 2-6mm were produced.
Water Research 04/2009; 43(7):1887-92. DOI:10.1016/j.watres.2009.02.007 · 5.53 Impact Factor
"Ammonia is completely soluble, and one would not normally expect any removal by separation beyond that of partition. Some ammonia can be removed as struvite in what is also known as the MAP process (magnesium–ammonia–phosphate ) (Munch and Barr, 2001; Laridi et al., 2005), but the quantity precipitated is modest compared to the large amounts of magnesium and phosphorous required. An alternative strategy is to adsorb the ammonia using zeolites, and then to separate as a nitrogen rich sludge. "
[Show abstract][Hide abstract] ABSTRACT: Separation processes have a distinct role in the management of livestock slurries, but it is important to recognise their limitations. Such technology can direct certain manure components into a small volume of a concentrated stream which is useful for the production of organic products in subsequent processes. Equipment generally falls into systems based either on mechanical screening (which can produce a fibrous and seemingly dry product), filtration processes (producing a cake), or sedimentation leading to a sludge product. Although physical separation can remove up to 80% of the total solids content from livestock manures, this will only include a relatively small part of the soluble nutrient and of the reactive organic matter; this is particularly so where separation is based on screens. The complete removal of all suspended matter (total clarification) of an effluent is theoretically possible by settling — a decanter centrifuge will accelerate the process. This can remove most of the phosphorous, especially if coupled with chemical pre-treatment to raise the pH. However, the clarified stream still retains a significant polluting potential in terms of the residual nitrogen content (as ammonia) and potassium. Only membrane separation can greatly reduce the potassium concentration, but such technology is rarely suitable for the farm situation.
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