Biological Treatment of Landfill Leachate at Elevated Temperature in the Presence of Polyurethane Foam of Various Porosity

Abstract

Application of sequencing batch reactors (SBR) for treatment of leachate from old, stabilized landfills, could be still an economically viable solution, as far as nitrogen removal is concerned. Very low amounts of accesible organic compounds requires an unconventional approach to treatment technology. In this paper the authors proposed utilisation of polyurethane (PU) foam of various porosity as a biomass carrier, hydraulic retention time (HRT) extended to 2 days and temperature elevated to 37°C, to stimulate simultaneous nitrification and denitrification (SND). The porosity of PU carriers had no effect on the efficiency of organic compounds removal, whilst the ammonium nitrogen (N-NH 4 þ ) removal efficiency was highest in the reactor (SBR2) equipped with PU cuboidshape carriers of 30 pores per inch (ppi), reaching 77.6%. In the reactor SBR3 filled with 15 ppi foam, the N-NH 4 þ removal efficiency was much lower (54.2%), but still better than observed in reference reactor, SBR1, operated with suspended activated sludge only (46.3%). The average free ammonia concentration in the effluents ranged from 140.18 to 347.98 mg/L at pH 9.6, depending on the reactor. Neither nitrites nor nitrates were found in the effluents, and the kinetics of N-NH 4 þ removal proceeded according to the first-order reaction.

Simultaneous Stripping of Ammonia from Leachate: Experimental Insights and Key Microbial Players

“…In turn, van Dongen et al [47] report that with NLR of 1.2 kg/m 3 •day, even over 80% of ammonium nitrogen has been converted to molecular nitrogen. In previous studies, Koc-Jurczyk and Jurczyk [22] have obtained that the efficiency of ammonium nitrogen removal ranged from 46.3% to 77.6%, depending on the porosity of the PU foam utilized as a biomass carrier. Wherein, the test was run in reactors intense aerated from the bottom (DO = 2 mg/L), and the carriers had the form of a submerged, loosely attached bunch of polymeric foam, without internal straight-run channels, that supports mass and temperature exchange.…”

“…The biomass carriers were made of polyurethane-reticulated open-cell foam. To estimate the total area of its complex internal structure, a methodology based on Weaire-Phelan foam-like structure was adopted [22] and the measurements of foam structural elements were taken from fifty randomly selected pores, by optical scanning of foam slices on a calibration grid (ImageJ1 [23]). The results of these calculations are shown in Table 1.…”

“…A selection of material used as a biomass carrier has a key importance; previous experiences in the application of different biomass carriers turned our attention to reticulated polymeric foams, characterized by porous but repetitive structures with a highly developed extended surface. These materials used as a filling in hybrid sequential reactors prevent biomass washout and create suitable conditions for simultaneous growth of aerobic and anaerobic microorganisms [22].…”

Biological treatment of leachate from stabilization of biodegradable municipal solid waste in a sequencing batch biofilm reactor

“…Numerous microbes secrete different enzymes, which cleave the complex macromolecules from leachate into simpler forms. Due to the hydrolyses and the activity of extracellular enzymes, carbohydrates, lipids or proteins, which are inaccessible to microorganisms in their present forms, can be converted into sugars, long chain fatty acids and amino acids (Henze and Mladenovski 1991). After they are broken down into smaller components, they can be utilized and diffuse through the cell membranes.…”

Assessing an Integral Treatment for Landfill Leachate Reverse Osmosis Concentrate

“…Landfill leachate is an extremely harmful wastewater for the environment because it contains a high amount of organic and inorganic pollutants. Several authors have studied different treatment alternatives to manage this highly contaminant-loaded wastewater, including biological [1], physical [2,3], and chemical processes [4,5]. Nowadays, physical processes using pressure-driven membranes (microfiltration and/or ultrafiltration followed by nanofiltration or reverse osmosis) [6][7][8] are widely used because of the high quality of the permeate water that is obtained.…”