The microwave enhanced advanced oxidation process (MW/H(2)O(2)-AOP) was adopted in successfully treating a multitude of organic slurries. The factor of ramp rate was incorporated in this study to investigate its correlations with different nutrients release into solution from waste activated sludge. Besides the ramp rate, the amount of time the samples were held at the treatment temperature to a total of 10 minutes aided in the isolation of held temperature from ramp rates, since different ramp rates will yield different reaction times. It was found that with the exception of orthophosphate and chemical oxygen demand release, ammonia and volatile fatty acids depended highly on the ramp rates. All constituents, chemical oxygen demand, orthophosphate, ammonia and volatile fatty acids, solubilized better with longer reaction times coupled with the highest ramp rate. Besides treatment time and ramp rates, treatment temperature and hydrogen peroxide dosage also play important roles in the release of various nutrients into solution by the MW/H(2)O(2)-AOP. The results from this study can aid in design parameters for the scaling up of a continuous microwave system for the MW/H(2)O(2)-AOP.

This study investigated the feasibility of treating the foams generated in enhanced biological phosphorus removal processes with the microwave-enhanced advanced oxidation process to reduce solids and solubilize nutrients for recovery purposes. It was found that more than half of the total chemical oxygen demand was solubilized during the treatment with just a small dose of hydrogen peroxide, signifying effective destruction of foam solids. Significant solubilization of phosphates, volatile fatty acids and ammonia was also observed, along with the release of metals contained in the foam, including calcium, potassium, and magnesium, which thereby represents additional potential benefits for nutrient recovery via subsequent crystallization processes. Since the solids content of foam is typically high, pretreatment for thickening sludge solids is not necessary prior to the use of microwave-enhanced advanced oxidation processes. As a result, this also offers further potential for reduction of energy costs. The process could be an efficient method for the removal and control of foam and the recovery of all available phosphorus at the same time.

This study investigates the effectiveness of the microwave enhanced advanced oxidation process (MW/H(2)O(2)-AOP) for nutrient release and cell destruction of the extracted activated sludge cells that are EPS-free. The concentrations of ammonia and soluble chemical oxygen demand increased with an increase of microwave temperature and hydrogen peroxide dosage. Orthophosphate could be released from these extracted cells at lower microwave temperatures and lower H(2)O(2) dosages compared to our previous studies using activated sludge. Higher concentrations of carbohydrate were released into the solution with an increase of microwave temperature. For the same microwave temperatures, carbohydrate release was first increased with the addition of H(2)O(2), and then decreased as the H(2)O(2) dosages increased further. The amount of DNA in solution was a good indicator of the extent of cell damage; the high concentration of DNA released into solution after treatment indicated significant cell damage.

A continuous flow mode of the microwave enhanced advanced oxidation process (MW/H2O2-AOP) was used for sludge treatment as opposed to a batch operation mode from past studies. The effects of pre-microwave heating, microwave irradiation and post-microwave holding on organic matter solubilization were studied. Pre-microwave heating did not improve the overall orthophosphate solubilization, but helped in organic matter solubilization. Nutrients and organic matter were found to have increased during the post-microwave holding period, indicating overall sludge solubilization can be more effective when maintained at a high temperature after treatment with the MW/H2O2-AOP. It was beneficial to operate a continuous mode of the MW/H2O2-AOP at a longer retention time for organic matter solubilization, and at a shorter retention time for orthophosphate solubilization. Sludge settleability was greatly improved with the microwave treatment, with or without the addition of H2O2. The pre-heating of sludge before treatment with the microwave process by the means of heat exchange can be beneficial for the overall organic matter solubilization in the MW/H2O2-AOP.Résumé : Un mode en écoulement continu du procédé d'oxydation avancée améliorée par micro-ondes (MW/H2O2-AOP) a été utilisé pour traiter des boues par rapport à un mode de fonctionnement par lot dans des études antérieures. Les effets du chauffage avant les micro-ondes, l'irradiation par micro-ondes et le maintien de la solubilization des matières organiques après les micro-ondes ont été étudiés. Le chauffage avant les micro-ondes n'a pas amélioré la solubilization globale des orthophosphates, mais a aidé à la solubilization des matières organiques. Les nutriments et les matières organiques ont augmenté durant la période de maintien après les micro-ondes, indiquant qu'une solubilization globale des boues peut être plus efficace lorsqu'elles sont maintenues à une température élevée après le traitement par le MW/H 2 O 2 -AOP. Il a été profitable de faire fonctionner le MW/H 2 O 2 -AOP en mode continu pour un temps de rétention plus élevé pour la solubilization des matières organiques, et à un temps de rétention plus court pour la solubilization des orthophosphates. La décantabilité des boues s'est grandement améliorée à la suite du traitement par micro-ondes, avec ou sans ajout de H 2 O 2 . Le préchauffage des boues par échange de chaleur avant le traitement par micro-ondes peut être avantageux pour la solubilization globale des matières organiques dans le MW/H 2 O 2 -AOP.

A continuous flow mode of the microwave enhanced advanced oxidation process (MW/H2O2-AOP) was used for sludge treatment as opposed to a batch operation mode from past studies. The effects of pre-microwave heating, microwave irradiation and post-microwave holding on organic matter solubilization were studied. Pre-microwave heating did not improve the overall orthophosphate solubilization, but helped in organic matter solubilization. Nutrients and organic matter were found to have increased during the post-microwave holding period, indicating overall sludge solubilization can be more effective when maintained at a high temperature after treatment with the MW/H2O2-AOP. It was beneficial to operate a continuous mode of the MW/H2O2-AOP at a longer retention time for organic matter solubilization, and at a shorter retention time for orthophosphate solubilization. Sludge settleability was greatly improved with the microwave treatment, with or without the addition of H2O2. The pre-heating of sludge before treatment with the microwave process by the means of heat exchange can be beneficial for the overall organic matter solubilization in the MW/H2O2-AOP.