Project # 1: Providing Access to Clean Water in Urban Centers Relying on Water Reuse Primary Faculty Mentor Dr Margaret J Kupferle Associate Professor, Environmental Engineering School of Energy, Environmental, Biological and Medical Engineering PO Box 210012 University of Cincinnati Cincinnati, OH 45221-0012 Office: 770 Engineering Research Center E-Mail: Margaret.Kupferle@uc.edu Phone: (513)-556-3329 Support Faculty Mentor Dr George Sorial Interim Director and Professor, Environmental Engineering School of Energy, Environmental, Biological and Medical Engineering PO Box 210012 University of Cincinnati Cincinnati, OH 45221-0012 Office: 701D Engineering Research Center E-Mail: George.sorial@uc.edu Phone: (513)-556-2987 Graduate Student Mentor Mr Liang Yan Graduate Student in Environmental Engineering Office: 712B Rhodes Hall E-Mail: yanlg@email.uc.edu Phone: 513-328-5542 Project Summary Providing access to clean water is one of the grand engineering challenges identified by the Natural Academy of Engineers (NAE) As populations continue to rise in the world’s urban centers, increasing demands will be placed on existing water supplies Reuse of treated wastewater will become necessary to supplement supply where surface water and groundwater are insufficient to keep pace with demand A primary challenge facing engineers developing water reuse treatment systems is the accumulation of organic matter such as synthetic trace organic compounds added to wastewater by consumers/users of the water Phenolic compounds are regarded as one major environmental concern around the world because they exist widely in industrial effluents Phenolic compounds potentially cause long-term contamination of both surface water and groundwater bodies Activated carbon adsorption is acknowledged as the most effective technology to remove phenolic compounds that persist in the environment However, the cost of adsorbents has been a major concern in activated carbon adsorption usage Studies of the adsorptive properties of granular activated carbon (GAC) for phenolic compounds found that the presence of molecular oxygen leads to a significant increase on the adsorption capacity of activated carbon for phenol due to oligomerization of phenols on the surface of activated carbon In addition, the products of oligomerization are very hard to be removed during the regeneration process So oligomerization of phenolic compounds can lead to poor regeneration efficiency of activated carbon Therefore, novel approach to produce activated carbon for hampering oligomerization, and will eventually render the activated carbon more cost effective is needed In our previous studies, systematic effort has been made to modify activated carbon for hampering the oligomerization of phenolic compounds and to examine the practical consequences of such modifications for oligomerization control One novel activated carbon had been successfully developed for removing phenolic compounds However, due to a limited understanding of the mechanisms of competitive adsorption, there is yet the need for investigating whether the presence of very high molecular weight natural organic matter (NOM) will impact the oligomerization control The objective of this project is to investigate the effect of the presence of NOMs on oligomerization control of phenolic compounds by novel activated carbon In this project the participants will explore a fundamental understanding of how novel activated carbons with optimal porous structure will work for oligomerization control in presence of NOMs The importance of determining the important variables for tailoring the activation process of activated carbon generated through novel ways for hampering oligomerization has a high scientific merit It will have a high impact in improving the regeneration efficiency of activated carbon This will eventually lead to selective choice of adsorption for a particular treatment application, and applying it in an effective manner Such carbon, while offering simple and cost-effective solutions to the needs of drinking water and waste water treatment industry to remove the organic matters, will also represent alternatives for sustainable use of environmental resources Based on our previous studies, the activated carbon with proper porous structure can be achieved by performing proper tailoring methods Chemical activation with KOH will be used here to create activated carbon sample with optimum BET surface area and pore size distribution (PSD) The raw material will be bituminous coal from Fisher Scientific Bituminous coal will be first grounded into powder by a ball mill (see Figure 1) And bituminous coal powder is physically mixed with KOH (KOH/coal mass ratio 2:1) to form a watery mixture and then introduced into a horizontal furnace (Thermolyne 79400) (See Figure 2) for overnight impregnation This mixture will be then activated at 650°C under a constant nitrogen gas flow of 400 ml/min for hrs The activated carbon sample is referred to BC-21 And one type of commercial GAC, F400 (Calgon Carbon Corp., Pittsburgh, PA), will be used for comparison All adsorbents used in this study will be crushed and sieved through 600 μm size sieve, dried in an oven at 105 oC overnight, and then stored in a desiccator until use For this experiment, the participants will be required to prepare the carbon samples and operate the necessary instrument Figure Ball Mill for Crushing of Carbon Figure Furnace for Carbon Activation In the next set of experiments, adsorption isotherm experiments will be conducted in amber bottles that have 125 ml volume, and two rotary tumblers will be used that have a 72 bottles maximum load capacity each (see Figure 3) For comparison purposes, isotherms of phenol, 2-Methylphenol and 2Ethylphenol will be conducted on both BC-21 and commercial F400 GAC The two representative NOMs that will be used for competitive adsorption are humic acid (HA) and fulvic acid (FA) The bottle point method will be used for conducting the adsorption isotherms at (20 ± oC) Two initial concentrations (200 mg/L and 1000 mg/L) of phenolic compounds and one target concentration of 12 mg/L NOM will be used To investigate the effectiveness of oligomerization control by carbon samples, both anoxic and oxic isotherms will be conducted: (1) For the anoxic isotherms, oxygen exclusion will be addressed Accurately weighed (±0.1 mg) masses of activated carbon will be placed in 125 ml glass amber bottles Amber bottles are chosen because they can inhibit photo degradation Then high-purity nitrogen will be used to purge carbon for one minute, twice a day for three days to remove molecular oxygen adsorbed on adsorbents The bottles will be tightly sealed with Teflon lined caps after purging Four liters adsorbate solutions will be prepared with autoclaved DI water buffered with KH 2PO4 and 10 M NaOH to pH 7.0 Before adding the phenolic compound, dissolved oxygen in the buffered NOMs solution will be eliminated by stripping the water with high-purity nitrogen for hrs Then phenolic compound will be added and mixed for one hour The headspace of the bottles will be kept under the head pressure of nitrogen to eliminate the presence of oxygen Then after mixing, the glass amber bottles containing the different masses of carbon will be completely filled with the adsorbate solution under small nitrogen flow purge Finally the bottles will be sealed tightly with Teflon lined caps and covered by parafilm The isotherm bottles will be then placed in a rotary shaker for two weeks; (2) For the oxic isotherms, accurately weighed (±0.1 mg) masses of carbon will be placed in 125 ml glass bottles Four liters adsorbate solutions will be prepared with autoclaved DI water buffered with KH 2PO4 and 10 M NaOH to pH 7.0 Then both NOM and phenolic compound will be added and mixed overnight 100 ml adsorbate solution will be added to each bottle Then glass amber bottles headspace will be purged with oxygen and then the bottles will be sealed with Teflon lined caps and covered by parafilm The isotherm bottles will be then placed in a rotary shaker for two weeks Finally, binary adsorptions isotherms of phenolic compounds by activated carbons in presence of NOM will be examined to investigate the influence of NOM in oligomerization control of phenolic compounds Both anoxic and oxic adsorption experiments will be performed Meanwhile, various target phenolic compounds concentrations and one NOM concentration of 12 mg/L will be applied Two blanks per set bottles will serve as controls during the isotherm experiments The sealed bottles will be then placed in a rotary tumbler for two weeks at 23 ± oC This time period is sufficient to reach equilibrium on activated carbons based on preliminary test results All samples from all bottles will be filtered, diluted, and analyzed by a HPLC system, as shown in Figure Then the UV analysis of the solution will be tested using a UV-VIS spectrophotometer (UV mini 1240, Shimadzu, Japan), as shown in Figure Using these test results, participants will be able to compare data for these compounds and demonstrate the difference of oligomerization control performance of phenolic compounds on activated carbons in presence of NOMs Figure Rotary Tumbler for Adsorption Isotherm Experiments Figure HPLC for determining phenolic compounds Concentration Figure UV-Vis