Topic Object to the Agenda: Contemporary methods for sludge degradation increase.

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1 IMPLEMENTATION OF BY THE USE OF SPECIALIZED MICROORGANISMS IN SEWAGE TREATMENT PLANTS IN ORDER TO IMPROVE THE QUALITY OF TREATED WASTEWATER AND THE SIGNIFICANT REDUCTION OF SLUDGE PRODUCTION Topic Object to the Agenda: Contemporary methods for sludge degradation increase. Authors: Dr. George Ganatsios Technical Director, Dr. Stylianos Papadopoulos General Manager, Mr. Andreas Ganatsios Senior Environmental Consultant, Dr. Christos Vatseris Senior Environmental Consultant, Mr. Periklis Pallis Senior Environmental Consultant. Alpha Bioenergy Ltd, Industrial Park of Thermi, Thermi GR 571, PO BOX 64, Thessaloniki, Greece., tel.: , fax: ABSTRACT The addition of specialized facultative bacteria which have the ability to function in aerobic, anaerobic and anoxic conditions may achieve a drastic increase in the efficiency of wastewater treatment as well as a significant reduction of the produced sludge. This technology is currently applied by the company Alpha Bioenergy in Greece and in other European countries. Aim of this paper is to present the results of the application of this technology at the Sewage Treatment Plant of the city of Patras for 213 and 214. A year s daily average measurements of treated wastewater before the implementation of bioaugmentation are presented and compared to the equivalent measurements of the year after the implementation. These parameters are: biochemical oxygen demand (BOD), total solids, total nitrogen (TN) and total phosphorus (TP). Furthermore, the produced sludge quantities were recorded for the same period. The final results showed significant reduction in all parameters and sludge production. 1. INTRODUCTION Activated sludge method is the most effective and widely spread process for municipal and/or industrial wastewater treatment. The main product resulting from the application of this method is biological surplus sludge, which consists primarily of cell mass produced by the biochemical decomposition of organic matter present in the incoming wastewater. Excess sludge treatment from sewage treatment plants (STP) becomes a really challenging task, entailing considerable technical difficulties and costs, typically corresponding to 25 65% of the total operating costs of such an installation. In addition, the treatment efficiency of a STP is often decreased by a series of parameters, such as seasonal fluctuations in the influent quality and flow rate, sludge bulking, technical malfunctions, extreme environmental conditions, recalcitrant pollutants, toxic shocks etc., resulting in poor effluent quality (Tchobanoglous et al., 23). As a result, more sophisticated technologies, towards the enhancement of STP's efficiency in terms of both effluent quality and energy utilization should be pointed out for implementation purposes. This study presents operational results from a long-term application of the bioaugmentation technology at Patras STP in Greece. The concentration of the main pollutants in the effluent (i.e. BOD 5, TSS, TN, TP) were routinely monitored and are

2 compared to the period before the application. In addition, the effect of the plant s long-term operation by implementing the bioaugementation technology on the surplus sludge production and the removal of micropollutants is discussed. 2. THE TECHNOLOGY Bioaugmentation is the practice of adding actively growing, specialized microbial strains into a microbial community in an effort to enhance the ability of the microbial community to respond to process fluctuations and/or to degrade certain compounds, resulting in improved treatment. By applying bioaugmentation the microbial community in the activated sludge regime can be enhanced, exhibiting improved resistance in toxic shocks, improved removal of slowly biodegradable compounds and increased removal of organic matter and macronutrients. By employing bioaugmentation, the core process of a wastewater facility can be enhanced. While other technologies (i.e. chemicals or consumables addition) can also increase effluent quality, such technologies are often expensive, hard to handle and cover up underlying problems with the microbial community. Bioaugmentation offers effective treatment without the capital investment associated to plant expansion and equipment solutions (Zhao and Wang, 212; Goel and Noguera, 26). Potential environmental and financial benefits from the application of the bioaugmentation technology include: Improvement of the treated wastewater quality Elimination of odors Reduction of the concentration of H 2 S in the generated gas (in anaerobic plants). In cases of further biogas utilization for power production, no investments for desulphurization units are necessary Surplus sludge reduction Increase of the plant capacity Resistance in sudden organic load fluctuations or in presence of toxic substances in the incoming wastewater Potential reuse of the effluent water for irrigation and other uses 3. The bioaugmentation technology was applied in the STP of Patras, located on a plot of 8 acres in the borders of the Municipality of Patras, (city in southern Greece), with a total capacity of 18. inhabitants. The treatment process is based on the activated sludge method with anaerobic stabilization of the excess sludge, biological nitrification, denitrification and phosphorous removal. A primary sedimentation stage precedes the biological reactors, aiming to the reduction of the incoming organic load. The daily flow of the incoming sewage is in the order of 38. m 3 /d, while the average concentrations of the main influent pollutants are mg COD/L, 5 7 mg NH 4 /L and 8 1 mg TP/L. The application of the bioaugmentation technology commenced on 4/1/214, by the controlled addition of specific facultative bacteria, able to grow in aerobic, anaerobic and anoxic environment.

3 TN (mg/l) TP (mg/l) BOD (mg/l) TSS (mg/l) average ,1 mg/l 25 mg/l average 214 6,9 mg/l average mg/l 3 mg/l average 214 9,44 mg/l a c 1 5 2/1/ /1/213 2/2/213 2/3/213 2/2/213 2/3/213 2/4/213 2/5/213 2/4/213 2/5/213 2/6/213 2/7/213 2/8/213 average ,4 mg/l 2/6/213 2/7/213 2/8/213 2/9/213 2/1/213 2/11/213 2/9/213 2/1/213 2/11/213 2/12/213 2/1/214 2/2/214 2/3/214 2/12/ mg/l 2/1/214 2/2/214 2/3/214 2/4/214 2/4/214 2/5/214 2/6/214 2/7/214 2/8/214 average mg/l 2/5/214 2/6/214 2/7/214 2/8/214 2/9/214 2/1/214 2/9/214 2/1/214 2/11/214 2/12/214 2/11/214 2/12/214 b d /1/ /1/213 2/2/213 2/3/213 2/2/213 2/3/213 2/4/213 2/5/213 2/4/213 2/5/213 2/6/213 2/7/213 2/8/213 average 213 3,4 mg/l 2/6/213 2/7/213 2/8/213 2/9/213 2/9/213 2/1/213 2/1/213 2/11/213 2/11/213 2/12/213 2/12/213 2/1/214 1 mg/l 2/1/214 2/2/214 2/3/214 2/2/214 2/3/214 2/4/214 2/5/214 2/4/214 2/5/214 2/6/214 2/7/214 2/8/214 2/9/214 2/1/214 average 214 2,3 mg/l 2/6/214 2/7/214 2/8/214 2/9/214 2/1/214 2/11/214 2/12/214 2/11/214 2/12/214 Figure 1: Time series of effluent concentrations of (a) BOD, (b) TSS, (c) TN and (d) TP in the Sewage Treatment Plant of Patras before and after application of the bioaugmentation technology

4 Production of dehydrated sludge in tn The positive effect of the implementation of the bioaugmentation technology on the efficiency of the STP of Patras is summarized in Figure 1. The application commencement is depicted with the green vertical line. As obviously shown, both organic compounds and macronurients (nitrogen and phosphorus) removal was significantly improved after the implementation of bioaugmentation. Average concentrations of BOD 5, Total Nitrogen and Total Phosphorus were determined equal to 6,9 mg/l, 6 mg/l and 2,3 mg/l after applying bioaugmentation, while the respective concentrations during the preceding period were 11,1 mg/l, 12,4 mg/l and 3,4 mg/l. The effluent clarification was also improved, exhibiting a mean Total Suspended Solids concentration of 9,44 mg/l, compared to 17 mg/l before application, as a result of improved sludge settling characteristics. The application of bioaugmentation also resulted in significant reduction of excess sludge production, as depicted in Figure 2. The corresponding dewatered sludge reduction during 214 was found equal to 75% if compared to 213 and even 79% if compared to the preceding years. The basic active mechanisms contributing to surplus sludge reduction during the application period are considered to be sludge enzymatic hydrolysis, activated sludge domination by slow growing species, as well as sludge endogenous decay Figure 2: Annual dewatered sludge production in the STP of Patras Bioaugmentation has also resulted in the efficient removal of specific micropollutants (i.e. pharmaceutical compounds) from the incoming wastewater. Figure 3 summarizes the average removal percentages of various pharmaceutical compounds during the application period in the STP of Patras. The results are presented in comparison with respective removal percentages from an activated sludge treatment plant in the same region (University Campus of Patras) during the same time period. The removal efficiency of the bioaugmented plant was consistently determined over 85% for all the compounds monitored, significantly higher than the respective removal percentages of the conventional STP (Koukoumis C., 215).

5 a b Figure 3: Removal percentages of specific pharmaceutical compounds (a) in STP of Patras during bioaugmentation period and (b) in university campus STP (source: Koukoumis C., 215) 4. CONCLUSIONS The significant advantages of the bioaugmentation technology after long-term application in a full-scale Sewage Treatment Plant have been consistently proven. Main pollutants were routinely monitored in the treated effluent before and after application. In addition, for the same period, the volume of produced excess sludge was recorded. The results exhibit significant improvement of the effluent characteristics and reduction of the surplus dewatered sludge. Significant reduction of micropollutants (i.e. pharmaceutical compounds) concentration has also been accomplished. Bioaugmentation has been practically proven to be a really promising technology towards upgrading the efficiency of wastewater treatment plants, resulting in important environmental and economical benefits.

6 5. REFERENCES Goel, R. K., and Noguera, D. R. (26). Evaluation of sludge yield and phosphorus removal in a cannibal solids reduction process. J. Environ. Eng. 132, Koukoumis C. (215) Pharmaceutical compounds detection and removal in sewage treatment plants, Post-Graduate Dissertation, University of Patras, Department of Chemical Engineering (In Greek). Tchobanoglous, G., Burton, F., Stensel, H.. (23) Wastewater Engineering: Treatment and Reuse. American Water Works Association, New York. Zhao Q. and Wang J. (212) Oxic-Settling-Anaerobic process for enhanced microbial decay. In: Paul E., Liu Y. (Eds.) Biological Sludge Minimization and Biomaterials/Bioenergy Recovery Technologies 1st Edition