Treatment Of Simulated Orange G Wastewater By Ozone/activated Carbon

The printing and dyeing enterprises in our country expend large amount of water and the produced wastewater is millions of tons every day which is one of the main kind of industrial wastewater.Due to the exist of large number of dye containing toxic aromatic groups in printing and dyeing wastewater,the printing and dyeing wastewater is having high chromaticity,difficult to be biodegraded and possessing complex,poisonous and harmful composition.Azo dye is widely used in printing and dyeing industry.Orang G(OG)is one of the azo dye and is usually used for dyeing of silk and cloth,etc.If the printing and dyeing wastewater is discharged into river directly,it can poison the aquatic animals and plants in the river and destroy the ecological environment in water.Ozone oxidation has some advantages such as high oxidation ability,cleanliness and high efficient which is one of the effective ways to treat printing and dyeing wastewater.Activated carbon has high specific surface area for total pore and micro-pore is developed and the feasibility of using activated carbon in printing and dyeing wastewater treatment is very high.AC/O3 has adsorption-oxidation system which is one of advanced oxidation technology.In this paper,azo dye Orange G was used as pollutant and was treated by ozone oxidation,activated carbon adsorption and adsorption-ozonation.First,OG removed by ozonation were researched.The results show that ozone oxidation can remove the OG effectively.The increase of ozone dosage and pH value benefit the removal of OG.The increase of temperature benefits the removal of OG in a certain range,but when the temperature is too high the effect will be opposite.The increase of OG initial concentration benefits the absolute removal amount but goes against the relative removal rate which increases the utilization efficiency of ozone.The effects of different metal ions on reaction are not the same.Cu2+ has no promoting and inhibition effect on ozonation,Co2+ has weak promoting effect and Mn2+ and Fe3+ have obvious promoting effect on ozonation reaction.Apparent kinetics study show that the ozonation reaction rate constant k and pH have positive correlation.When the temperature is in the range of 10 ? to 40 ?,the ozonation reaction rate constant k and temperature have positive correlation,but when the temperature is up to 50 ?,the k decreases.Second,the effects of activated carbon dosage,reaction time and salt concentration on OG adsorption were studied.The adsorption isotherm,adsorption kinetics and activation energy of adsorption were also researched.The results show that the removal rate of OG increases after the increase of activated carbon dosage,but the adsorption quantity of one unit of activated carbon decreases.The first 10 minutes is the fast adsorption phase;After 10 minutes,removal rate increases slowly,and 10?40 min is the slow adsorption period;After 40 minutes,the adsorption reaches equilibrium.When the activated carbon dosage is 2.5 g·L-1,the removal rate of OG is 95.5%in 40 minutes.This adsorption process follows the Langmuir isotherm equation and pseudo second-order equation.The increase of initial OG concentration and temperature benefit the equilibrium absorption capacity qe.The energy of activation for adsorption is small and the studied adsorption is mainly a physical adsorption process.At last,the effects of activated carbon dosage,activated carbon particle size and ·OH capture agent on AC/O3 system were researched.The results show that when ozone dosage is 810 mg·h-1 and OG concentration is 1 g·L-1,the optimal activated carbon dosage is 5 g·L-1,where OG removal rate and COD removal rate can reach 83.3%and 37.8%respectively.PAC is better than GAC and the ·OH capture agent tertiary butyl alcohol(TBA)can inhibit the reaction.