Simultaneous nitrification–denitrification of wastewater: effect of zeolite as a support in sequential batch reactor with step-feed strategy

Abstract

One of the technologies used for wastewater nitrogen removal consists in simultaneous nitrificationdenitrification. The low microbial growth rate and the low availability of organic material for the denitrification stage make it necessary to study new operational conditions and the use of microbial supports. The aim of this study was to evaluate the operational behavior of a simultaneous nitrification-denitrification process in a sequential batch reactor utilizing zeolite as a biomass support and step-feed strategy. Two reactors of 2 L were used, one with zeolite and another without zeolite, both operated at constant temperature (31°C), varying nitrogen loading rate (NLR) from 0.041 to 0.113 kg total Kjeldahl nitrogen (TKN/m 3 /day). After 209 days, removals higher than 86 and 96 % in nitrogen compounds and organic matter were obtained, respectively. There was not accumulation of nitrate and nitrite in any case; this means that there was a simultaneous nitrification-denitrification in the reactors. The incorporation of zeolite in the system held higher concentration of biomass in the reactor; this led to reduce start-up to 21 days and to improve 11.31 % removal kinetic. The use of a stepfeed strategy prevents events of inhibition by substrate, even duplicating tolerance to higher NLR for the same operation time.

Partial Nitrification in a Sequencing Moving Bed Biofilm Reactor (SMBBR) with Zeolite as Biomass Carrier: Effect of Sulfide Pulses and Organic Matter Presence

“…Thus, zeolite enabled a faster recovery of the AOB activity, a condition attributed to the ionic exchange capacity of the zeolite, which adsorbs the ammonia and makes it available for the AOB growth to affect the biofilm on the zeolite surface. This fact was also reported by other researchers in nitrifying systems [10,[33][34][35]. A similar situation was observed with the NOB activity, where the system with zeolite recovered 100% of its capacity of nitrite oxidation after 20 days, while the system without zeolite could not completely recover its nitrite oxidation capacity (70%).…”

Nitrification in the presence of sulfide and organic matter in a sequencing moving bed biofilm reactor (SMBBR) with zeolite as biomass carrier

“…There are several reports on the biofilm formation on zeolite and how this can help improve different kinds of biological processes. The biofilm formation was monitored through optical microscopy up to ×40., and pictured in Figure .…”

“…Fernandez et al indicated that zeolites with diameters between 200 and 800 μm improved the anaerobic digestion in a fluidized bed reactor, allowing the growth of biomass on the zeolite surface. For the case of nitrification, Guerrero et al indicated that zeolite diameters between 800 and 1200 μm improved the nitrification process, whereas Huiliñir et al in a batch system (without biofilm formation) indicated that the nitrification improved for zeolite with diameters between 250 and 500 μm. None of these studies using different zeolite diameters showed or studied the biofilm thickness in their systems.…”

Potential Application of Chilean Natural Zeolite as a Support Medium in Treatment Wetlands for Removing Ammonium and Phosphate from Wastewater

“…Finally, taking into account the previous discussion, the Chilean natural zeolite with a commercial size of 1.5-3.0 mm is recommended to be used as the support media in treatment wetlands to remove N and P from domestic wastewaters, including those produced in rural areas. In addition, after saturation in treatment wetlands, the Chilean natural zeolite has the possibility to be used as a source of nutrients, namely N and P, as has already been proposed by several authors [27,[68][69][70].…”