Quantitative dynamics of ammonia-oxidizers during biological stabilization of municipal landﬁll leachate pretreated by Fenton’s reagent at neutral pH Lukasz Jurczyk ⇑ , Justyna Koc-Jurczyk University of Rzeszow, Department of Biology and Agriculture, Cwiklinskiej 1b Str., 35-601 Rzeszow, Poland article info Article history: Received 6 October 2016 Revised 4 January 2017 Accepted 17 January 2017 Available online xxxx Keywords: Landﬁll leachate Fenton’s reagent Sequencing Batch Reactor (SBR) Quantitative PCR Ammonium Oxidizing Bacteria (AOB) Nitrite Oxidizing Bacteria (NOB) Free Ammonia Nitrogen (FAN) abstract The application of multi-stage systems including biological step, for the treatment of leachate from municipal landﬁlls, is economically and technologically justiﬁed. When microbial activity is utilized as 2nd stage of treatment, the task of 1st stage is to increase the bioavailability of organic matter. In this work, the effect of advanced oxidation process by Fenton’s reagent for treatment efﬁciency of landﬁll lea- chate in the sequencing batch reactor was assessed. The quantitative dynamics of bacteria taking a part in ammonia removal process was evaluated by determination of number of DNA copies of 16S rRNA and amoA. Products of neutral pH chemical oxidation, had a deﬁnite positive impact on the quantity of b-proteobacteria 16S rRNA, whereas the same gene speciﬁed for Nitrospira sp. as well as amoA did not show a signiﬁcant increase during the process of biological treatment, regardless of whether the reactor was fed with raw leachate or chemically pre-treated. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction Although, landﬁlling is not the best solution from the environ- mental risk point of view, it is still the commonest method of municipal waste management in most of European countries, including Poland, due to both technological and economic reasons (Cossu, 2010). One of the major adverse effects of waste dumping is formation of the leachate. This dark liquid is produced as a result of dissolving, mainly in rainwater percolating the landﬁll, products of physical, chemical and biological reactions occurring in the lay- ers of dumped waste (Aziz et al., 2010). Properly designed munic- ipal landﬁll should be effectively insulated from the ground to collect the entire volume of leachate by drainage system, and, where it’s possible, direct it into a treatment system. There are numerous methods and modiﬁcations proposed for efﬁcient treat- ment of landﬁll leachate (Renou et al., 2008), which could be divided in three main groups; ﬁrst covers the techniques based on physical, chemical or combined processes, as: reduction of vol- ume by ultraﬁltration and reverse osmosis (Peters, 1998; F. Li et al., 2009; Pi et al., 2009; Renou et al., 2009), or evaporation (di Palma et al., 2002), ammonia striping (Cheung et al., 1997; Ferraz et al., 2013), decomposition of refractory organic compounds by radioly- sis or ozonolysis (Cataldo and Angelini, 2012), advanced chemical or electrochemical oxidation (Amiri and Sabour, 2014; Fernandes et al., 2015, 2016; Moreira et al., 2016) or supercritical water oxi- dation (Wang et al., 2011; C. Gong et al., 2015; Y. Gong et al., 2015), coagulation and ﬂocculation or adsorption (Labanowski et al., 2010; Oloibiri et al., 2015) or combination of those methods. The second group concerns methods of biological treatment, based on microbial activity of suspended sludge or bioﬁlm, maintained in miscellaneous types of reactors (Koc-Jurczyk, 2014). If landﬁlls are located close enough to WWTP, some authors also propose dilution of leachate in municipal wastewater, sometimes with additional supplementation with external carbon source (Ye et al., 2014). In practice the problem of leachate is often only temporarily sus- pended by mechanical recirculation and spattering the liquid back on the surface of landﬁll with or without additional processing (Xing et al., 2013; Talalaj and Biedka, 2015). In recent years it is becoming more common to combine above mentioned groups of methods in multi-stage systems concerning physio-chemical and biological treatment in various order (Silva et al., 2013; Abood et al., 2014). The age of landﬁll is considered as a main factor determining choice of the method of leachate treatment, because it inﬂuences the most chemical characteristics of leachate. Leachate from young landﬁlls, during the acidic phase, are characterized by low pH, aver- age concentrations of ammonium nitrogen (500–2000 mg L 1 ), http://dx.doi.org/10.1016/j.wasman.2017.01.028 0956-053X/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: ljurczyk@ur.edu.pl (L. Jurczyk). Waste Management xxx (2017) xxx–xxx Contents lists available at ScienceDirect Waste Management journal homepage: www.elsevier.com/locate/wasman Please cite this article in press as: Jurczyk, L., Koc-Jurczyk, J. Quantitative dynamics of ammonia-oxidizers during biological stabilization of municipal land- ﬁll leachate pretreated by Fenton’s reagent at neutral pH. Waste Management (2017), http://dx.doi.org/10.1016/j.wasman.2017.01.028