Effect of filters including zeolite, perlite and resin on Biochemical & Chemical Oxygen Demand (Case Study: Mahallat Wastewater)

Introduction: In recent years, water crisis has caused wastewater using in agriculture section. According to the welcome and the need to use wastewater and recycled water in agriculture, more wastewater treatment plants in the country with the aim of reuse of wastewater in agriculture, are designed and implemented. Treatment action cause to the amount of organic material to be refined. So, Investigation of wastewater pollution reduce is necessary .In this Investigation, the use of filters and natural absorbent such as zeolite, perlite and anionic resin to improve wastewater characteristics will be examined.
Material and Methods: This study was conducted in 18 PVC columns to evaluate the combination filters, including modified zeolite, perlite and anion resins to reduce pollution in wastewater. Test units are made of PVC pipe internal diameter 10.5 cm and a height of 60 cm. Five centimeters bottom of each column were filled out using a sand filter to prevent soil particles. On the sand filter, to a height of 40 cm of soil or soil combined with modified zeolite, perlite and anion resin as mixed or layers was filled. The experiment consisted of nine treatments and two replications. The statistical plan was conducted in a completely randomized plan with two factors. The first factor, the use of modified zeolite, perlite and resin include of two mixed and layer by layer types and the second factor is the percentage of modified zeolite, perlite and resin in two levels 2 and 4 weight percent. To measure BOD5 and COD, wastewater was injected in columns 10 times the frequency of weekly. Drainage wastewater collect from columns 24 hours after were irrigated. After the ninth round took a leaching. Then the samples were transferred to the laboratory for the measurement of BOD5 and COD.
Result and Discussion: The results show that layer treatment including zeolite, perlite and resin with 4 weight percent, has the highest effect among all treatments. As amount of BOD5 and COD declined more than 47 and 16 percent, respectively. Control treatment has the lowest effect with 36.2 percent for BOD5 and 12.26percent for COD, too. Also, results show the use of zeolite, perlite and resin to form of mixed, cause to reduce the BOD5 and COD than the control column, but the layer column are more able to reduce them. Moreover, effect of perlite is more than to zeolite to decline BOD5 and COD and more weight percent of used particles cause more effect of them.
Conclusion: The results show, used filters decline more in BOD5 and COD than to control treatment. But weight percent change of filters from 2 to 4 percent doesn’t have a lot of effect on BOD5 and COD.
Application of combination filter as layer by layer including zeolite, perlite and resin with 4 weight percent has most effect on reduce of output BOD5 and COD and the lowest of effect is for zeolite filter with 2 weight percent. One of the reasons for higher ability to remove BOD5 and COD wastewater in layer column is slower passing of water from this column. Zeolite, perlite and resin layers in the soil column prevent the cross of organic material and due to the low concentration of organic matter in the drainage water, chemical and biochemical oxygen demand was reduced. Also, compare of the BOD5 and COD amount of output from test columns to the amount authorized for use in agriculture shows that its value is less than the allowed limit.