Chanil Jung

Adsorption of selected endocrine disrupting compounds and pharmaceuticals on activated biochars.

Chemically activated biochar produced under oxygenated (O-biochar) and oxygen-free (N-biochar) conditions were characterized and the adsorption of endocrine disrupting compounds (EDCs): bisphenol A (BPA), atrazine (ATR), 17 α-ethinylestradiol (EE2), and pharmaceutical active compounds (PhACs); sulfamethoxazole (SMX), carbamazepine (CBM), diclofenac (DCF), ibuprofen (IBP) on both biochars and commercialized powdered activated carbon (PAC) were investigated. Characteristic analysis of adsorbents by solid-state nuclear magnetic resonance (NMR) was conducted to determine better understanding about the EDCs/PhACs adsorption. N-biochar consisted of higher polarity moieties with more alkyl (0-45 ppm), methoxyl (45-63 ppm), O-alkyl (63-108 ppm), and carboxyl carbon (165-187 ppm) content than other adsorbents, while aromaticity of O-biochar was higher than that of N-biochar. O-biochar was composed mostly of aromatic moieties, with low H/C and O/C ratios compared to the highly polarized N-biochar that contained diverse polar functional groups. The higher surface area and pore volume of N-biochar resulted in higher adsorption capacity toward EDCs/PhACs along with atomic-level molecular structural property than O-biochar and PAC. N-biochar had a highest adsorption capacity of all chemicals, suggesting that N-biochar derived from loblolly pine chip is a promising sorbent for agricultural and environmental applications. The adsorption of pH-sensitive dissociable SMX, DCF, IBP, and BPA varied and the order of adsorption capacity was correlated with the hydrophobicity (Kow) of adsorbates throughout the all adsorbents, whereas adsorption of non-ionizable CBM, ATR, and EE2 in varied pH allowed adsorbents to interact with hydrophobic property of adsorbates steadily throughout the study.

Removal of humic and tannic acids by adsorption–coagulation combined systems with activated biochar

Despite recent interest in transforming biomass into bio-oil and syngas, there is inadequate information on the compatibility of byproducts (e.g., biochar) with agriculture and water purification infrastructures. A pyrolysis at 300°C yields efficient production of biochar, and its physicochemical properties can be improved by chemical activation, resulting in a suitable adsorbent for the removal of natural organic matter (NOM), including hydrophobic and hydrophilic substances, such as humic acids (HA) and tannic acids (TA), respectively. In this study, the adsorption affinities of different HA and TA combinations in NOM solutions were evaluated, and higher adsorption affinity of TA onto activated biochar (AB) produced in the laboratory was observed due to its superior chemisorption tendencies and size-exclusion effects compared with that of HA, whereas hydrophobic interactions between adsorbent and adsorbate were deficient. Assessment of the AB role in an adsorption-coagulation hybrid system as nuclei for coagulation in the presence of aluminum sulfate (alum) showed a synergistic effect in a HA-dominated NOM solution. An AB-alum hybrid system with a high proportion of HA in the NOM solution may be applicable as an end-of-pipe solution.

Mitigation and degradation of natural organic matters (NOMs) during ferrate(VI) application for drinking water treatment.

Ferrate(VI), as an alternative for pre-oxidation in drinking water treatment, has recently captured renewed interest. However, the knowledge in ferrate(VI) chemistry remains largely undeveloped. The information regarding ferrate(VI) reactions with natural organic matters (NOMs), an important water matrix component affecting water treatment, is highly limited. In this study, bench scale tests were performed to study ferrate(VI) decay and reactions with NOMs in a typical surface water matrix. Results showed that ferrate(VI) decay exhibited a pseudo 2nd-order reaction pattern (kobs = 15.2-1.6 mM(-1) min(-1) and 36.3-4.0 mM(-1) min(-1) with 1.0-7.0 mg/L Fe(VI) at initial pH 7.8 and 5.8, respectively), suggesting that self-decomposition is principally responsible for ferrate(VI) consumption. Ferrate(VI) tended to attacked electron-rich moieties in NOM molecules, but had limited capability to mineralize NOMs. Consequently, ferrate(VI) effectively reduced UV254 and specific UV absorbance (SUVA254), but poorly removed dissolved organic carbon (DOC). Generally, lower pH and higher ferrate(VI) dose favored the NOM destruction. Fe(VI) (3.0 mg/L) could remove 16% of initial DOC (4.43 mg/L), 56% of initial UV254 (0.063 cm(-1)), and 48% of initial SUVA254 (0.033 cm(-1) (mg/L)(-1)) at pH 5.80. Further organics analyses indicate that ferrate(VI) readily degraded hydrophobic and transphilic NOM fractions, but scarcely decomposed hydrophilic fraction. Fluorescence excitation-emission matrix (EEM) and fluorescence regional integration (FRI) analyses revealed that ferrate(VI) preferentially reacted with fulvic-like (region III) and humic-like (region V) substances and certain aromatic proteins (region II), difficultly decomposed soluble microbial byproducts (region IV), and rarely oxidized aromatic proteins in region I.

Feasibility Study on Removal of Total Suspended Solid in Wastewater with Compressed Media Filter

Recently, as a variety of techniques of CMF (Compressed media filter) that has advantages of high porosity and compressibility have been developed in the U.S. and Japan. Therefore, the interest of intensive wastewater treatment using CMF has grown. This study examined the feasibility of CMF with varying sewage water quality to determine the optimum operating conditions. A preliminary tracer test that investigated the filtering process under various compression and flow rate conditions was performed. In a high compression condition, different porosities were applied to each depth of the column. Therefore, a distinct difference between a theoretical value and results of tracer test was observed. For the TSS (Total suspended solid) removal and particle size distribution of CMF for pre-treatment water under the various compression conditions, the compression ratio of 30 percent as the optimal condition showed greater than 70% removal efficiency. In addition, the compression ratio of >15% was required to remove small-sized particles. Also, an additional process such as coagulation is necessary to increase the removal efficiency for <10 μm particles, since these small particles significantly influence the effluent concentration. Modeling results showed that as the compression rate was increased, TSS removal efficiency in accordance with each particle size in the initial filtration was noticeably observed. The modeling results according to the depth of column targeting 10 μm particles having the largest percentage in particle size distribution showed that 150-300 mm in filter media layer was the most active with respect to the filtering.

Characterization of ultraviolet-quenching dissolved organic matter (DOM) in mature and young leachates before and after biological pre-treatment

The discharge of municipal landfill leachate into publicly owned treatment works (POTWs) is a common leachate management practice in the United States. However, the benefits of this option have diminished in many POTWs because leachate can significantly interfere with UV disinfection due to the introduction of UV-quenching substances (UVQS). This study aims to characterize UV-quenching dissolved organic matter (DOM) in different raw and sequencing batch reactor (SBR) pre-treated landfill leachates. Nine leachate samples, including four raw mature leachates, four SBR pre-treated mature leachates, and one young raw leachate, were investigated. The mature leachates, regardless of raw or SBR pre-treated ones, had lower biodegradability (low BOD5/COD), higher specific UV absorbance (SUVA), greater hydrophobic fraction, and more high molecular weight (MW) organic compounds than the young leachate. SUVA served as a useful indicator for the characterization of UV-quenching DOM, which exponentially declined with increasing BOD5/COD. The high SUVA of the mature leachates suggests a highly aromatic and hydrophobic character with a high fraction of aquatic humic matter and high MW compounds. In contrast, the low SUVA of the young leachate implies the presence of a high fraction of non-humic matter, a highly aliphatic character, and more low MW molecules. After the mature leachates were biologically pre-treated, the SUVA increased due to the partial degradation of high MW compounds. Results from fluorescence excitation–emission matrix (EEM) analysis could effectively reflect the variation of hydrophobic DOM, but poorly indicated the presence of hydrophilic DOM.