Treatment of Low Biodegradability Leachates in a Serial System of Aged Refuse-Filled Bioreactors

Abstract

This paper presents a technology based on the use of aged refuse that has proven to be highly effective in the treatment of low biodegradability leachates. The tests were developed using two filled bioreactors arranged in series and operated at steady state. The aged refuse used as filling material was extracted from a city located in the southeast of Mexico and characterized by particle size, humidity, volatile solids, and volumetric weight. On the other hand, bacterial characterization made it possible to identify the presence of species related to the degradation and mineralization of organic compounds, as well as to processes of nitrification or reduction of phosphates and Cr (VI). The bioreactor system was operated under four hydraulic loads (10,20,35, and 50 L/m 3 ·d). Maximum removal efficiencies of 85, 86.1, 87.9, 98.6, 97.8, and 97.4% were achieved in COD, BOD 5 , Color, TP, TN, and N-NH 3 , respectively, complying with Mexican regulations (NOM-001- SEMARNAT-1996). The system also proved to be stable against shock loads, such as organic load fluctuations in the influent or pH variations. The results of this study show that, in countries such as Mexico, aged refuse extracted from landfills represents a promising option as a sustainable alternative for leachate treatment.Sustainability 2019, 11, 3193 2 of 16 of them are refractory and toxic, such as heavy metals. In general, the leachates can be classified as: young (less than 5 years of being generated), intermediate (between 5 and 10 years of being generated), and stabilized or mature (more than 10 years of being generated) [3].The treatment of leachates has been studied practically with all physical, chemical, and biological processes applied in the field of water treatment, highlighting processes such as adsorption, membrane systems, coagulation-flocculation, chemical oxidation, and biological systems [4]. Physicochemical processes have been applied as the first stage of purification of low biodegradability leachates, usually accompanied by biological processes to improve the efficacy of the treatment [5][6][7]. On the other hand, biological processes achieve good efficiencies when applied to young leachates, but are less effective in the treatment of mature leachates [8].In Mexico, leachates have been treated mainly by evaporation and recirculation; however, this method is not advisable because during evaporation water is emitted to the atmosphere as well as volatile organic compounds [9]. In the case of the state of Chiapas, in southeastern Mexico, due to high annual rainfalls, the generation of leachates is abundant, which causes the capacity of evaporation lagoons to be exceeded and, as a consequence, the method of evaporation and recirculation is even more questionable.A novel approach to leachate treatment consists of the use of MSW extracted from landfills after more than 8 years of being disposed on the site. This material, called stabilized material or aged refuse (AR), is used as packaging in bioreactors, generating a friendly, sustainable, ...

Comparison of two leachate treatment systems by use of bioreactors packed with stabilized material of different age

“…Concentrations of some heavy metals (Cd, Pb and Cu) are also observed, but are below typical levels in mature leachates (2 mg/L) (Renou et al, 2008;Nájera-Aguilar et al, 2019). These results were similar to those found by Méndez et al, (2008) for the Mérida landfill, Yucatán, México, with respect to the values of heavy metals removed, although by an air flotation method.…”

Differences in the Composition of Leachate from Active and Non-Operational Municipal Waste Landfills in Poland

“…This indicates an early acetogenic phase of waste decomposition, when the pH value usually does not exceed 6.6. Leachate from mature landfills, that have been in operation for more than 10 years [46], reaches values higher than 7.5 as volatile fatty acids are converted into methane and carbon dioxide [10,47]. The alkaline nature of the leachate is characteristic of the methanogenic phase and leachates from mature landfills [48].…”

Novel Treatment of Sugar Mill Wastewater in a Coupled System of Aged Refuse Filled Bioreactors (ARFB): Full-Scale

“…Thus, although the BI was lower than that reported in other studies, it is sufficient to treat wastewater by biological processes. Even more so under the ARFB technology, which has proven to be efficient both in biodegradable wastewater and with low biodegradability [21].…”

“…These high efficiencies showed by the ARFB system are attributed to the microbial activity in aged refuse, derived from the existence of large and diverse populations of microorganisms that have acclimatized to high concentrations of contaminants over the years, developing a great capacity to even degrade refractory (insoluble and nonhydrolyzable) organic matter [20,21].…”