The microwave enhanced advanced oxidation process (MW-AOP) has been applied to pre-treat different sludge types and high solids content. Secondary sludge not only had the highest solids and nutrient content but also yielded higher treatment efficiency than primary or mixed sludge. In the case of secondary sludge with 4% total solids (TS), the total suspended solids (TSS) concentration was reduced by 32% while soluble chemical oxygen demand concentration increased from 1% to 40% after treatment at 110 degrees C. A high level of nutrient release was also achieved; about 65% total phosphate (TP) solubilized at 110 degrees C. The degree of secondary sludge disintegration was dictated by temperature and hydrogen peroxide dosage. The optimal operating temperature for the system was 110 degrees C, and sludge containing TS up to 8% was treated effectively. Secondary sludge with 8% TS had a TSS reduction of 41% after treatment at 110 degrees C while COD solubilization was about 45%; about 55% TP was solubilized at 10 min holding time. Treatment of sludge with higher solids content would allow for handling larger amounts of sludge at a given period and reduce heating cost per unit of treated sludge. The inter-relationship between the degree of sludge disintegration and changes in chemical and physical properties was also clearly demonstrated here. The treated sludge would be an ideal substrate for anaerobic digestion or phosphorous recovery processes. High levels of nutrients (phosphorus and nitrogen) and metal release, and solids disintegration from sludge containing high solids content would make subsequent resource recovery processes more effective and economical.

In this study, two metal-organic frameworks [MIL-100(Fe) and MIL-101(Cr)] are fabricated and investigated to determine their ability to remove Cu2+, Cd2+, and Pb2+ from aqueous solution. MIL-100(Fe) and MIL-101(Cr) exhibited fast adsorption kinetics, achieving equilibrium in approximately 0.5 h. To evaluate the adsorption capacities of MIL-100(Fe) and MIL-101(Cr), the experimental data was fit to the Linear, Freundlich, and Langmuir isotherm models. Based on the sum of the squared error analysis, the experimental data fit most closely to the Freundlich model, followed closely by the Linear isotherm model. However, the values for the Freundlich parameter n were close to 1, which suggests that the adsorption followed the Linear isotherm model. The K-LIN adsorption affinity coefficient [(mg/g)/(mg/L)] for the Linear isotherm model was the largest for Cu2+ (K-LIN,K- MIL100(Fe) = 14.9; K-LIN,K- MIL-101(Cr) = 60.3), followed by Cd2+ (K-LIN,K- MIL-100(Fe) = 12.9; K-LIN,K- MIL-101(Cr) = 11.5) and Pb2+ (K-LIN,K- MIL-100(Fe) = 4.44; K-LIN,K- (MIL-101(Cr)) = 8.33). Characterization data of MIL-100(Fe) and MIL-101(Cr) showed specific surface areas of 1586 m(2)/g and 2505 m(2)/g for MIL-100(Fe) and MIL-101(Cr), respectively, along with the presence of various functional groups, including carboxyl and phenyl groups. Considering this data alongside the local energy decomposition analysis that was performed using molecular modeling, electrostatic interactions were determined to be the dominant adsorption mechanism for the removal of Cu2+, Cd2+, and Pb2+ by MIL-100 (Fe) and MIL-101(Cr), which is consistent with other, similar adsorption studies. This study shows that MIL-100 (Fe) and MIL-101(Cr) are effective adsorbents for the removal of heavy metals from aqueous solution.

Fats, oils, and grease (FOG) and source separated organics (SSO) were treated with the microwave-enhanced advanced oxidation process (MW-AOP) at 90 and 110 °C, with varying amounts of hydrogen peroxide dosages. The treatment efficiency, in terms of soluble substrates and volatile fatty acids (VFA), increased with an increase in both temperature hydrogen peroxide dosages. Fatty acids and compounds with carbonyl group and/or hydroxyl group in both initial and treated FOG samples were identified by gas chromatography-mass spectrometry. MW-AOP treatment temperatures and hydrogen peroxide dosages dictated the formation of degradation products. The degradation followed peroxidation mechanism to produce lower molecular weight substrates such as short chain fatty acids which would be less inhibitory to microbes. After the MW-AOP treatment, both SSO and FOG comprised of more soluble and low molecular weight compounds. These compounds included VFA and nutrients that would be readily available for bacterial or plant uptake.