The biodegradation of monomeric and dimeric alkylammonium surfactants

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<ul><li><p>R</p><p>Ta</p><p>BL</p><p>h</p><p>a</p><p>ARRAA</p><p>KBQGW</p><p>C</p><p>mcthcDEits</p><p>h0</p><p>Journal of Hazardous Materials 280 (2014) 797815</p><p>Contents lists available at ScienceDirect</p><p>Journal of Hazardous Materials</p><p>j o ur nal ho me pa ge: www.elsev ier .com/ locate / jhazmat</p><p>eview</p><p>he biodegradation of monomeric and dimericlkylammonium surfactants</p><p>ogumi Brycki , Magorzata Waligrska, Adrianna Szulcaboratory of Microbiocides Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, Poznan 60-780, Poland</p><p> i g h l i g h t s</p><p>The biodegradation of alkylammonium surfactants is described and discussed.The degradation process is very complex and depends on many factors.Monomeric and dimeric alkylammonium surfactants are hard to be degraded.Amide, peptide or carbohydrate substituents facilitate the biodegradation.</p><p> r t i c l e i n f o</p><p>rticle history:eceived 20 May 2014eceived in revised form 29 July 2014ccepted 6 August 2014vailable online 24 August 2014</p><p>eywords:iodegradationuaternary alkylammonium salts</p><p>a b s t r a c t</p><p>Quaternary ammonium compounds (QACs) are salts known for having antiseptic and disinfectant prop-erties. These compounds are toxic to aquatic organisms and should thus be removed from wastewaterbefore its discharge into surface waters. The biodegradation of QACs takes place in the presence ofmicroorganisms under aerobic conditions. The susceptibility of these compounds to degradation dependson numerous parameters. A number of them, such as the structure-adsorption on solids, and con-centration of the QACs, as well as the presence of additional substances, have been reviewed in thisarticle. Moreover, the biodegradability of new dimeric alkylammonium salts, i.e., cationic gemini surfac-tants, has been discussed and compared with that of anionic and nonionic geminis. The biodegradationemini surfactantsastewater treatment</p><p>study of monomeric and dimeric alkylammonium surfactants show that they are not easily degraded.The degradation process is very complex and strongly depends on the structure of the compound,adsorptiondesorption processes on sludge, type of microorganism consortia and the presence of anions.Alkylammonium surfactants with biological motifs, like amide, peptides or carbohydrates, are muchbetter degraded.</p><p> 2014 Elsevier B.V. All rights reserved.ontents1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Biodegradation of quaternary alkylammonium salts . . . . . . . . . . . . . . . . . . . . . .</p><p>Abbreviations: ACh-Cl, acetylcholine chloride; AnBUSDiC, test anaerobic biodeonium compounds; BAC, benzalkonium chloride; BNR, biologic nitrogen removahloride; C10TMAC, decyltrimethylammonium chloride; C12BAC, dodecylbenzyldimethyetradecylbenzyldimethylammonium chloride; C14TMAC, tetradecyltrimethylammoniuexadecyltrimethylammonium bromide; C16TMAC, hexadecyltrimethylammonium chyltrimethylammonium chloride; C22TMAC, docosyltrimethylammonium chloride; CMC,EEDMAC, diethylesterdimethylammonium chloride; DOC, dissolved organic carbon; Dcotoxicology and Toxicology of Chemicals; FEC, first effect concentration; HEQ, Hamburgnhibition constant; LAS, linear alkylbenzene sulphonate; LCh-Cl, lauroylcholine chloride; Mional Trade and Industry-Japan; OECD, Organization for Economic Co-operation and Develudge; SDS, sodium dodecyl sulphate; SRT, solid retention time; VSS, volatile suspended Corresponding author. Tel.: +48 61 829 1314; fax: +48 61 829 1505.</p><p>E-mail address: brycki@amu.edu.pl (B. Brycki).</p><p>ttp://dx.doi.org/10.1016/j.jhazmat.2014.08.021304-3894/ 2014 Elsevier B.V. All rights reserved.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 798 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800</p><p>gradation under sludge digester conditions test; ATMAC, alkyltrimethylam-l; BOD, biochemical oxygen demand; C10DMAC, didecyldimethylammoniumlammonium chloride; C12TMAC, dodecyltrimethylammonium chloride; C14BAC,m chloride; C16BAC, hexadecylbenzyldimethylammonium chloride; C16TMAB,loride; C18DMAC, dioctadecyldimethylammonium chloride; C18TMAC, octade-</p><p> critical micelle concentration; DADMAC, dialkyldimethylammonium compounds;TDMAC, ditallowdimethylammonium chloride; ECETOC, European Centre for the</p><p> ester quat; ISO, International Organization for Standardization; KI , half-saturatione, methyl group; MIC, minimal inhibitory concentration; MITI, Ministry of Interna-</p><p>lopment; QAC, quaternary ammonium compound; SCAS, semicontinuous activated solids; WWTP, wastewater treatment plant.</p><p>dx.doi.org/10.1016/j.jhazmat.2014.08.021http://www.sciencedirect.com/science/journal/03043894http://www.elsevier.com/locate/jhazmathttp://crossmark.crossref.org/dialog/?doi=10.1016/j.jhazmat.2014.08.021&amp;domain=pdfmailto:brycki@amu.edu.pldx.doi.org/10.1016/j.jhazmat.2014.08.021</p></li><li><p>798 B. Brycki et al. / Journal of Hazardous Materials 280 (2014) 797815</p><p>2.1. Microorganisms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8002.2. Biodegradation technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8002.3. Biodegradation mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8012.4. QAC biodegradation kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8022.5. Influence of QAC structure on its biodegradation kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8032.6. Influence of QAC adsorption on its biodegradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8032.7. Influence of anions on the biodegradation of QACs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8042.8. Influence of QAC concentration and microbial adaptation on QAC biodegradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 804</p><p>3. Biodegradation of gemini surfactants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8054. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 813</p><p>. . . . . .</p><p>1</p><p>wpmToagipmpaitPoE</p><p>piefsmitomsef</p><p>iatippb</p><p>o</p><p>F</p><p>References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . </p><p>. Introduction</p><p>Quaternary ammonium compounds (QACs, quats) are moleculesith at least one long hydrophobic hydrocarbon chain linked to aositively charged nitrogen atom (Fig. 1). The other alkyl groups areostly short-chain substituents such as methyl or benzyl groups.he counter ions can be either inorganic or organic. QACs havever 10% share in a large group of surfactants, where anionicnd non-ionic surfactants combined account for roughly 85% oflobal demand for surfactants. [1]. Despite the global trend to non-onic surfactants, QACs will remain the widely used surfactants inharmaceutical and fabric softener formulations, cosmetics, com-ercial disinfectants, industrial saniters, food preservatives, andhase transfer catalysts [2]. Global demand for non-ionic, anionic,mphoteric and cationic surfactants was over 12 million tonnesn 2010 and is projected to rise by 4.5% per year until 2018o generate revenues of more than US$41 billion in 2018. Asia-acific is the largest surfactant outlet, with a roughly 37% sharef global consumption, followed by North America and Westernurope [1].Residual surfactants are discharged to wastewater treatment</p><p>lants (WWTPs) or directly to surface waters and then dispersednto the environment. However, surfactants have some negativeffects on surface waters, such as reducing air/water oxygen trans-er, damaging the water quality via the introduction of foam andorption on solid particles, and exerting a toxic effect on aquaticicroorganisms in trophic levels [3]. Hence, it is necessary to</p><p>nvestigate the susceptibility of these compounds to biodegrada-ion as well as the mechanisms of this process in the presencef mixed cultures, i.e. microbial consortia with well establishedutual interactions isolated from activated sludge, wastewater,ediments, and rivers. However, it is hard to predict degradationfficiency or contamination level in the environment due to severalactors.</p><p>Two types of biodegradation can be distinguished. The first types primary biodegradation, during which a biological action causesn alteration in the chemical structure of a substance, resulting inhe loss of a specific property of that substance. The second types ultimate biodegradation (mineralisation), in which the test com-ound is completely utilised by microorganisms, resulting in the</p><p>roduction of carbon dioxide, water, mineral salts, and new micro-ial cellular constituents (biomass) [4,5].The ultimate biodegradability (mineralisation) of QACs in aer-</p><p>bic environments can be measured according to one of the</p><p>ig. 1. Structures of quaternary ammonium salts, where R1, R2, R3, R4 = CH3,CnH2n+1 (n = 818), CH2C6H5; X = inorganic or organic ions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 813</p><p>five following methods: the CO2 headspace test, carbon dioxideevolution (modified Sturm test), closed-bottle test, manometricrespirometry test, and MITI test. According to those tests, surfac-tants are readily biodegradable if at least 60% biodegradation isachieved within 28 days. Ultimate biodegradability can be eval-uated using the following tests: dissolved organic carbon (DOC)die-away and modified OECD screening-DOC die-away. The passcriterion of at least 70% of these two methods is considered equiv-alent to the pass criterion of at least 60% referred to in the methodslisted earlier. In all methods testing ultimate biodegradability, pre-adaptation is not required and the 10-day window principle is notapplied [5,6]. Environmental mineralisation is usually determinedwith either radio- or stable isotopes. The most frequently miner-alisation rates are determined by using 14C-labelled start materialand trapping the formed 14CO2 [7].</p><p>The primary biodegradability of QACs can be evaluated accord-ing to one of methods mentioned in Regulation EC No 648/2004,based on the disulphine blue active substance analysis orusing appropriate specific instrumental analyses, such as high-performance liquid chromatography [8].</p><p>Based on concern for the natural environment, the EuropeanParliament and the Council of the European Union have devel-oped regulations regarding synthetic surfactants. The RegulationEC No 648/2004, along with further amendments, harmonises thebiodegradability of surfactants in detergents and restrictions onor bans of surfactants on grounds of biodegradability. In accor-dance with these regulations, detergents containing surfactantsthat meet the criteria for ultimate aerobic biodegradation (readilybiodegradable surfactants) may be placed on the market withoutfurther limitations relating to biodegradability. For all surfactants indetergents failing ultimate aerobic biodegradation tests, the level ofprimary biodegradability shall be measured, and if it exceeds 80%,the manufacturers of industrial or institutional detergents contain-ing surfactants may ask for derogation [8].</p><p>Although anaerobic biodegradation is not required for surfac-tants in the regulations discussed above, there was an intentionto undertake further research to explore improved methods formeasuring anaerobic biodegradability [9]. Knowledge about QACanaerobic biodegradation is important because the strong adsorp-tion of quaternary ammonium compounds on solid particlescan occur in anaerobic environments, such as river sediments,sub-surface soil layers, or sludge digesters of wastewater treat-ment plants. Methods for testing anaerobic biodegradability canbe divided into screening tests for the determination of basicbiodegradability under stringent conditions (e.g., ISO 11734, OECD311) and tests at the simulation level, such as the OECD 314 orAnBUSDiC tests, for the assessment of data under more realisticconditions [914]. However, simulation tests are complex, lengthyand expensive; therefore, most surfactants have been aerobicallytested in screening tests [11].The strategy of OECD tests consists of three levels, i.e., readybiodegradability tests or screening tests, inherent biodegradabilitytests and simulation tests. Biodegradability tests generally neglect</p></li><li><p>rdous </p><p>ksiaietbm</p><p>lndv[rt[</p><p>otwattac1enai,dqbbsal</p><p>wspriF2asts</p><p>Yldnodl(</p><p>sSm3</p><p>surface water and sediments; hence, knowledge of their biodegrad-ability has become important. In this paper, the biodegradation ofcationic gemini surfactants will be discussed and compared withthe biodegradation of anionic and nonionic geminis.B. Brycki et al. / Journal of Haza</p><p>inetics...</p></li></ul>