Microwave Enhanced Advanced Oxidation Process Application to Treatment of Dairy Manure

Phosphorus recovery as struvite from farm, municipal and industrial waste: Feedstock suitability, methods and pre-treatments

“…The common chemicals used are oxidants, acids and bases. Combined microwave-chemical treatment is more effective at releasing P than microwaving only (Qureshi et al, 2008;Lo et al, 2011). The 80% release of P demonstrated by Pan et al (2006) after microwaving dairy slurry was increased to 85% when H 2 O 2 treatment was incorporated.…”

“…From microwave treated P enhanced dairy manure, up to 90% of orthophosphate recovery as struvite is possible (Qureshi et al, 2008). Use of H 2 O 2 reduces the required temperature for optimum P release and hydroxyl radicals react with organic particulate P to release P into solution (Lo et al, 2011). Xiao et al (2015) more recently showed that microwaving activated sludge as a pre-treatment prior to anaerobic stirring for 1 h maximized phosphate release with a recovery efficiency of 95% in the form of amorphous calcium phosphate and struvite.…”

“…Microwave irradiation has been suggested as a pre-treatment method to release particulate P for enhanced struvite recovery (Liao et al, 2005;Pan et al, 2006;Chan et al, 2007;Qureshi et al, 2008;Lo et al, 2011) and the extent of P release depends upon the forms of P present in the source materials (Pan et al, 2006). The degree of P solubilisation depends upon microwave operating temperature and duration of heating (Liao et al, 2005) with 120 o C considered to be the optimum temperature for releasing both NH 4 + and P in sewage sludge (Chan et al, 2007).…”

“…Pan et al (2006) showed an 80% release of P following microwave treatment (170 o C) of liquid dairy manure. The advantages of microwave treatment over conventional heating include uniform heating throughout the material, precise control over process temperature and no direct contact between heating source and materials (Lo et al, 2011).…”

Effect of pre-heating on microwave enhanced advanced oxidation process

“…Elevated microwave temperatures (>80°C) increase the decomposition of hydrogen peroxide into hydroxyl radicals and therefore increase the oxidation rate, resulting in a higher degree of solubilisation of the substrate (Eskicioglu et al, 2008;Liao et al, 2007). Lo and Liao (2011) suggested an optimum MW temperature of 120°C for best nutrient recovery and solids disintegration from sludge and dairy manure in a batch mode MW/H 2 O 2 -AOP. However, continuous-flow 2450-MHz microwave systems, both laboratory-scale and pilot-scale, were tested at near 100°C or below (Yu et al, 2010;Zhang et al, 2013).…”