Iranian Journal of

Background and Objectives: Wet air oxidation (WAO) is One of the advanced oxidation process which reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substances and, solid waste leachate,etc. In this study the efficiency of wet air oxidation method in leachate treatment generating from Esfahan Composting factory was Evaluated.
Material and Methods: The experiment was carried out by adding 1.5 Lit of pretreated leachate sample the steel reactor with the volume of 3L. The reactor then underwent10 bar pressure at different temperature (100, 200 and 300 °C) and various retention time (30, 60 and 90 min). Leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 Lit was taken and the WAO method, was used for pre-treatments. Removal efficiency of COD, BOD, NH4-N, NO3 and TSS were examined.
Results: The results showed that the removal efficiency was more than 35% for COD, 38% for BOD, and 85% for TSS within one hour of reaction. The Maximum removal efficiency obtained in this study were 53.3% for NH4-N and 73.9 % forNO3-N.
Conclusion: the results indicate that the reaction temperatures are the most important factors affecting degradation of organic matter. COD and BOD5 removal efficiency by WAO process increased as the time of reaction went up. In addition, BOD5/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of leachate sample, were determined and improved grately as it reached to 84%. TheWAO process presented in this paper is considered an efficient process for pretreatment of leachate, as the COD, BOD5 and NO3 reduction observed in leachate samples.

Backgrounds and Objectives: Wet air oxidation (WAO) is one of the advanced oxidation process which is mostly used to reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substance and solid waste leachate.The objective of this paper is comparisons of three advance oxidation in organic matter removal in different conditions from Esfahan composing factory leachate
Material and Methods: The experiment was carried out by adding 1.5 Lit pretreated leachate sample to 3Lit autoclave reactor and adding 10 bar pressure at temperature of 100, 200 and 300 °C and pressure (10 bars) with retention time of 30, 60 and 90 min. leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 lit was taken and the three methodsWAO, WPO, and a combination of WAO/GAC were used for pre-treatments. Pure oxygen and 30% hydrogen peroxide was used as oxidation agent.
Results: The result shows significant improvement on the removal rate of COD (7.8-33.3%), BOD5 (14.7-50.6%)by WAO process.The removal efficiency of 4.6-34% COD, 24-50% BOD, was observed in the reactor.Adding theGACto the reactor improved removal efficiency of all parameters.Combination Process (WAO/GAC) removed 48% of COD, 31-43.6% of BOD.Combination process demonstrated higher efficiency than two other previous methods as BOD5/COD ratio of 90% achieved.
Conclusion: The WAO process presented in this paper is efficient for pretreatment of leachate, And the modified WPO process remove organic materials and ammonia moreover WAO/GAC can be considered as an excellent alternative treatment for removing reluctant organic matter (COD, BOD5) and organic nitrogen compounds, which found in leachate.

Background and Objectives: Phenol is one of priority pollutants produced through leather, paint, resin, and pharmaceutical industries and it can contaminate groundwater after entering to the environment. Hence, it is necessary to use a suitable method for its removal. The aim of this study was synthesize and efficiency evaluation of magnetic nanocomposite of activated carbon powder-zero valent iron/silver (PAC-Fe^o/Ag) in the removal of phenol from aqueous solution. Material & Methods: Reduction method was used for converting bivalent iron to zero valent iron and co-precipitation method for depositing of iron on activated carbon. For coating silver on nano zero valent iron, rapid mixing at high temperature was used. The adsorbent was characterized using SEM, TEM, and XRD techniques. Then, the impact of pH, contact time, agitation speed, temperature, adsorbent, and initial phenol concentration were evaluated and optimized by one factor at the time method. Reaction kinetics and isotherms were also determined. Results: It was found that PAC-Fe^o/Ag has cubic and intertwined structure and has a diameter in the range from 40 to 100 nm. The optimum conditions for phenol removal by PAC-Fe^o/Ag were as pH=3, 90 min contact time, 200 rpm agitating speed and adsorbent concentration equal to 1 g/l. Isotherm and kinetic equations showed that the experimental data of phenol adsorption onto PAC-Fe^o/Ag are correlated to the Langmuir (R²>0.969) and pseudo-second order (R²<0.965) models, respectively. Conclusion: Under optimum conditions, modified adsorbent by zero valent iron and silver with maximum efficiency of 97% has quickly and effectively ability in removal of phenol and it can be easily separated from the solution sample by magnet because of its magnetic properties.

Background and Objective: About 1.35×10⁵ tons of pistachio waste are produced in annually Iran that can result in environmental problems if managed improperly. . The purpose of this study was to investigate in-vessel composting of pistachio residuals with addition of cow manure and dewatered sludge as a recycling alternative.

Materials and Methods: Pistachios wastes were combined with weight ratio of 5.5:10 (dewatered sludge: pistachio waste) and weight ratio of 1:10 (Cow manure: pistachio waste) to achieve the carbon to nitrogen ratio of 25:1. The parameters measured were pH, EC, percentage of moisture, total and volatile solids, ash, organic carbon, temperature, and phenol. The 20^th edition of SPSS software was used for t-test statistical analysis and comparing the results with standards and Microsoft Excel 2007 was used for drawing the plots.

Results: During the 60-days process of in-vessel composting of pistachio residuals with addition of cow manure, the ratio of carbon to nitrogen reduced from 25:1 to 13:1, dewatered sludge from 25:1 to 14:1; phenol amount in cow maneuver decreased from 4980 to 254 ppm and in dewatered sewage sludge from 6100 to 254 ppm. The maximum temperature in cow manure and dewatered sewage sludge treatments in the composting process reached to 51.9 and 48.9 ˚C respectively.

Conclusion: Results showed that the produced compost with cow manure has a higher fertilizing value compared with the dewatered sewage sludge due to its better organic degradation.

Background and Objective: Dewatered sewage sludge is a by-product of wastewater treatment process which can cause health and environmental problems if not properly managed. The aim of this study was to determine the feasibility of composting of Yazd WWT dewatered sludge with windrow method using different treatments.

Materials and Methods: In this study, the dewatered sewage sludge was mixed with two treatments of agricultural wastes (straw) and green waste (leaves), respectively. The mixture was done based on weight ratio of 20:1 and 10:1 (agricultural waste: dewatered sludge, and green waste: dewatered sludge) to achieve a ratio of C/N:20. The windrows were built with a length of 2 m, width of 75 cm and height of 1.5 m. Composting process was controlled by measuring the temperature, humidity, volatile solids, ash, pH, EC, organic carbon and estimating the C/N ratio. The results were compared with those of the Institute of Standards and Industrial Research of Iran.

Results: After 100 days of composting, C/N ratio was 13.08±6.25 in the treatment with green waste and reached to 15.46±5.35 in the treatment with agricultural waste. The amount of volatile solids decreased to 19.8±14.01% and 20.71±16.06% in the treatments with green waste and agricultural waste, respectively. The amount of EC had an increasing trend in both treatments.

Conclusion: composting with both treatments was led to an improvement in indicators of organic fertilizers in dewatered sewage. However, the windrow containing green waste reached to the mature compost standards sooner than the windrow containing agricultural waste.