Native Zeolites in Domestic Wastewater Treatment

Abstract

Natural zeolites have a high purification capacity in wastewater due to their porosity, specific surface, cation exchange capacity and they are a product available in nature. In Tabasco, Mexico, river and hill zeolites were evaluated to see their potential in wastewater treatment. First, an experimental system of three upflow fixed-bed bioreactors (UFBB) with a height of 1.5 meters and diameter of 4 inches was designed and built, then the potential of native zeolites and a commercial control in the field were evaluated. sewage treatment. The UFBB were started with a 3x3 factorial design, operating with river zeolite, hill zeolite and commercial zeolite (control), all with ? inch particles, using three different bed heights (0.75, 0.90 and 1.10 m) and three times. hydraulic retention (6, 12 and 24 hours). The response variables were evaluated by means of a multifactorial ANOVA and to discriminate between the means the Fisher's least significant difference (LSD) method (p < 0.05, 95 % confidence) was used. The closed zeolite presented (average, N=10) the best physicochemical characteristics with are real and apparent density of 2700 and 1470 kg/m3 respectively, specific weight 2240 kg/m3, porosity of 62 %, absorption of 15.20 %, solubility in hydrochloric acid of 29.96 %, pH of 7.4 and electrical conductivity of 70 mS/cm. The residual water with which the treatments were developed was applied prior to the experiment a primary treatment (grid, sand trap, skimmer and septic tank) and presented temperature values (average, N = 9) of 25.26 ? C, pH of 8.63, Total dissolved solids with 950.50 mg/L, color of 1305.10 UC, turbidity 96.37 NTU and chemical oxygen demand of 373 mg/L. Of the zeolites evaluated (N = 81) in the UFBB, the one that presented the best treatment was the hill zeolite operating with a bed height of 0.9 m and with 24 hours of hydraulic retention time, obtaining the best removal efficiencies with 71.42 % in total dissolved solids, 84.34 % for turbidity, 96.33 % for color and 97.28 % for the chemical oxygen demand, followed by the commercial zeolite that had very similar responses and finally the river zeolite treatment that also presents good results in comparison with other means of support. The optimal height in the UFBB was 0.9 m, an important factor to evaluate since the higher the elevation costs are increased and the efficiencies are not relevant to justify the investment and the lower the performance in quality of the treated water falls. Finally, native zeolites have ideal properties to be used in the treatment of domestic wastewater and we can recommend the implementation of UFBB in the secondary treatment of domestic effluents in decentralized systems in the southeast of Mexico as a viable alternative in the treatment of their domestic wastewater.