Background: Dissolved air floatation (DAF) is one of the methods has been used for the sludge thickening in wastewater treatment plants. This study aimed to investigate the effects of coagulation and sonication processes as additional configurations on the efficiency of a lab-scale DAF process for thickening of the biological sludge of an industrial wastewater treatment plant in Kashan, Iran. Methods: The required amounts of sludge samples were collected from a wastewater treatment plant and kept at temperature of 4°C. Variables, such as pressure (3, 5, and 7 atm), flotation time (5 and 10 minutes), ultrasonic irradiation power (0, 75, and 150 W), and presence/absence of Fe-based coagulant were considered on a sequencing batch reactor (SBR) included coagulation, flotation, and sonication processes, respectively. Results: The use of ultrasonic waves led to an insignificant increase in the DAF efficiency (P > 0.05), however, the application of coagulant significantly increased the thickening efficiency (P < 0.05). The maximum efficiency of the process was achieved at flotation time of 5 min, pressure of 3 atm, and sonication power of 75 W. Conclusion: According to the results, DAF has a proper efficiency for thickening of biological sludge. Coagulation compared to sonication has a greater effect on the efficiency of the process.

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The insect infestation of stored grain and their products is a serious problem over the world since it reduces crop yields, causes contamination for stored products, damages seed germs, carries diseases that effect plants, peoples, animals, and changes the quality of stored products. Six compounds, one organophosphorus, pirimiphose methyl, two biocides; ivomic and Bacillus thuringiensis, one mineral oil (KZ), one insect growth regulator, cascade and one organic acid, formic acid were evaluated against Trogoderma granarium by exposure to treated media and other two ones were layer manner. Based on LC 50,s values, data indicated that primiphos-methyl was the most toxic compound with LC 50 of 0.135 ug/g, while the least toxic one was the mineral oil with LC 50 value of 4300 ug/g grain at 24 h post-treatment. The efficacy of the biocide ivomic followed the effect of pirimiphos-methyl. Data obtained cleared that cascade had a higher toxic effects on the tested insect than the mineral oil formic acid. Batches of grains (wheat grain) were mixed using the three mentioned manners. Based on the behavior of stored product insects which quickly move between grains where contact with the treated media. Results obtained showed that half and one third of dose had more percent of mortality than the expected values. The down position of treated layer indicated the most effect compared to the other two layers (middle and surface).

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