1. An efficient sludge based activated carbon for anaerobic degradation of industrial effluents S. Athalathil a, E. Torrens a, A. Fortuny b, and A. Fabregat a a Departament d’Enginyeria Qu´ımica, ETSEQ, Universitat Rovira i Virgili, Av. Pa¨ısos Catalans 26, 43007 Tarragona, Catalunya, Spain b Departament d’Enginyeria Qu´ımica, EPSEVG, Universitat Polit´ecnica de Catalunya, Av. V´ıctor Balaguer s/n, 08800 Vilanova i la Geltr´u, Catalunya, Spain Phone No: 0034-644065160 Fax: 0034-977559667 E-Mail: sunil.athalathil@urv.cat Introduction Experimental set of Continuous upflow packed-bed reactor in laboratory Preparation of Sludge based carbon and microbial consortia Results: Catalytic characterization Results: Catalytic performance Conclusions References Acknowledgements Objectives: Reactor conditions: Sludge based activated carbon: 1 g Model compound: Acid Orange II Feed dye conc. : 100 mg/L Feed bottle temp. : 5 o C pH inlet and out let : 6.8 - 7.4 Flow rate : 15 ml/h -1 to 240 ml/h -1 Reactor temp: 35 o C Redox potential : 400- 500 Mv (Ag+/AgCl electrode) Table 1. Characterization of raw sludge and sludge based carbon Figure 2. FT-IR spectra of raw sludge and sludge based carbon Quartz Calcite Many industrial wastewater effluents, from textile, paper and cosmetic industries, contain organic pollutants that are coloured and highly toxics. Discharge of organic pollutants from effluents in open water reservoirs affects hazardous health and limits photosynthesis in aquatic plants. European Union (2010) reported the production of sewage sludge matter of 9 million tonnes in the year of 2005. These huge amount of waste materials are available almost free of cost and they cause major disposal problems. If the solid wastes are used as low cost adsorbents (LCAs) reducing the environmental problems. Activated carbons are usually obtained from carbonaceous raw materials using conventional processes but an alternative method is the use of sewage sludge. It is used for different applications, but most of the treatment associated with effluents. The biological activated carbon process utilizes sludge based carbon to adsorb organics and to act as a support for microorganisms. The present work investigates the production of sludge based carbon (SBC) from the wastewater treatment plant sludge. To perform the catalytic efficiency of SBC for anaerobic degradation of azo dye (acid orange II) in Continuous upflow packed-bed reactor (UPBR) system. Cabrita, I., Ruiz, B., Mestre, A.S., Fonseca, I.M., Carvalho, A.P., Ania, C.O., 2010. Chem. Eng. J. 163, 249-255. Mezohegyi, G., Kolodkin, A., Castro, U.I., Bengoa, C., Stuber, F., Font, J., Fabregat, A., 2007. Ind. Eng. Chem. Res. 46, 6788-6792.0 Doctoral student Mr. Sunil Athalathil, is gratefully acknowledge the fellowship from Universitat Rovira i Virgili, the financial support provided BRDI. Project Code: 2010BRDI/06 - 35 Sludge based Carbon Pretreatment Filtration Basal media & nutriants Drying at 105 o C Washing with DW Sieving adequates size WWTP Chemical treatment ZnCl 2 /sludge (1:1) 2h impergination Washing with 5M HCl Drying & Store Preparation of activated carbon Preparation of mixed culture Anaerobic mesophilic sludge Bio reactor UPBR Liquid Solid Microbacterial consortia Maintain anaerobic condition Carbonization at 400 o C Mechanism of Acid orange dye degradation pathway Materials and methods Sludge type: Secondary anaerobic mesophilic sludge was collected from waste water treatment plant, WWTP, Reus Station, Tarragona, Spain. Chemical activation procedure : Briefly, the raw sludge material was impregnated with Zinc Chloride ( ZnCl 2 ) solution ( ratio of 1:1 wt. %) and stirred for a period of 2 h. The imperginated simples was carbonizad for 2 h dwell time at 400 o C temperatutre in an oven. The produced activated carbon was washed with 5M HCl and followed by distilled water. Bacterial immobilization: In UPBR reactor anaerobic bacterial consortia immobilized in to sludge activated carbon to generate biofilm. SBC Raw sludge AdsorbentsSpecific surface area ( m 2 /g) Total pore volume ( cm 3 /g) Average pore diameter (A) Raw sludge SBC 6.15 186.89 0.0195 0.1579 101.26 34.39 In UPBR system- Biological sludge based carbon, almost complete decolorization was achieved at short space time. These material has been proved as very strong supportive for biological consortia immobilization and less microbial fouling. In comparison of commercial carbon as well as sludge based activated carbon was applied to biological degradation of AO7 at different space time (τ) has been determined. The catalytic efficacy of chemically activated sludge materials was found fairly close capacities as compared to commercially activated carbon. Thus, chemical activation of zinc chloride as a simple valorization of wastewater treatment plant sludge to prepare inexpensive activated carbon. FTIR spectra gives the different functional groups presence in surface of the materials. Many compounds disappeared when heating at high temperature. The raw sludge showed the major adsorption bands at 2923 cm -1, 1631, 1539, 1419, 1020 and 873 cm -1. After the chemical treatment some of the bands disappeared on the surface of activated carbon peaks at 2923, 1539 and 1419 cm -1. The XRD spectra of the raw sludge material obtained two sharp observed at 2 theta 27 and 29.5. These peaks are related quartz and calcite respectively. When this sludge treated with zncl2 the major peak of Calcite peaks eliminated from the surface of the sludge activated carbon. (a) (b) SEM picture showing chemical treatment increased the rigidity of surface. The dried sludge material contains more homogeneous pore and loosely arrangement of space. In this images clearly seen the porous area and a surface area lower than 6 m 2 /g. The sludge material after chemical activation of zinc chloride results became a hard shape and heterogeneous pore. Surface are increase when temperature with presence of chemical compounds and also increased the adsorption capacities of azo dyes degradation. The chemical activation of sludge materials surface area and total pore volume was found around 186.89 m 2 /g and 0.1579 cm 3 /g. Figure 4. Nitrogen adsorption/desorptions isotherm for raw sludge In UPBR reactor system almost complete decolorization was achieved at short space time. AO7 conversion was about 98 % at 4 min, 96 % at 2 min, 75 at 1 min 60 % at 0.5 and 0.25 min of t resulted in 29% of decolorization achieved as compared to commercial activated carbon. Initially the higher space time color removal efficiencies increased could be adsorption dye on to the biological catalyst. In static adsorption experiment, the produced adsorbents were tested for their adsorption capacity of Acid orange II. The concentration of AO7 varied from 100 mg/L and 500 mg/L. It can be seen that for raw sludge and SBC, the adsorption capacities increased with the concentration, from 3.24 mg/g to 42.90 mg/g and 42.08 mg/g to 85.52 mg/g, respectively. The adsorption isotherms of raw sludge and sludge based carbon given in Fig. 4 & 5. The comparison between these two isotherms, it was found that the isotherm of the sludge based activated carbon exhibited more sleeper at higher relative pressure as compared to raw sludge. This also suggests that the sludge based activated carbon to be more micro porous with the raw sludge. Figure 3. XRD patterns of raw sludge and sludge based carbon Picture 1. SEM micrographs of (a) raw sludge, (b) sludge based carbon Figure 6. Influence of initial dye concentration on adsorption capacity Figure 7. Adsorption isotherms for raw sludge and sludge based carbon Figure 5. Nitrogen adsorption/desorptions isotherm for sludge based carbon Figure 1. Continuous and anaerobic upflow packed-bed reactor set up Diagram 1. Preparation for mixed culture and sludge based carbon from the waste water treatment plants. SBC Raw sludge 12 th Mediterranean Congress of Chemical Engineering. Barcelona, Spain November 15-18,2011