Treatment of tannery wastewater in a sequencing batch reactor

Abstract

The aim of the research was to study the treatability of tannery wastewater by a sequencing batch reactor (SBR) compared with a continuous flow full scale reactor. The experimental work presented in this paper was carried out on a laboratory scale anoxic-aerobic SBR fed with tannery wastewater coming from a full scale continuous flow treatment plant located in S. Miniato (Pisa, Italy). After a long acclimation period, a complete and stable nitrification has been developed. The denitrification was always performed without any additional carbon source with good results when influent COD/TKN ratio was higher than 8 and with a higher rate compared to that obtained in the continuous plant. When high effluent nitrate occurred, it was due only to stoichiometric (not kinetic) limitations. The organic substrate removal occurred mainly during the anoxic period and a high effluent COD (refractory) was often present at the end of the process. This research has shown the suitability of the industrial wastewater (particularly tannery wastewater) treatment by SBR because of its several advantages compared to the continuous reactors: i.e. a higher versatility and the possibility to work with higher loads (smaller volumes), by selecting, through the cyclic concentration gradients, a biomass resistant to the presence of inhibiting substances (often encountered in industrial wastewaters).

Nitrogen and cod removal from tannery wastewater using biological and physicochemical treatments

“…The principle diagram of the biological system with all major components is shown in Figure 1. SBR worked by predenitrification strategy since many researchers have shown its effectiveness to remove nitrogen from tannery and slaughterhouse wastewaters [3,4,21,22]. The main phases in the SBR were anoxic filling, reaction phase (anoxic -oxic -anoxic), settling and decanting, no external carbon source was added.…”

“…During the evaluation of the SBR performance, a decrease in removal efficiency of N-NH 4 + and TKN was observed at day 35 of the reactor operation (Figure 4), due to the increment in nitrogen concentration in the raw tannery wastewater. Ammonia concentration increased from 93.0 to 149.3 mg·L -1 and the TKN from 185.5 to 213.5 mg·L -1 , attributable to changes in operating conditions in the tannery processes.…”

“…In recent years, sequencing batch reactors (SBR) have shown good removal efficiencies for nitrogen and organic carbon contained in industrial wastewater with inhibiting substances [4]. SBR also provides the advantage that nitrogen removal can be carried out in a single reactor by maintaining anoxic and aerobic stages sequentially [5,6].…”

“…Results show the integrated treatment system was effective to produce an effluent suitable for discharge into water bodies, according to the Venezuelan environmental regulations. Average effluent concentrations were 303 mg COD L , giving COD, TN and N-NH 4 + removals of 80%, 82% and 99.6%, respectively. Profiles of ORP, DO and pH were efficient ways to monitor the evolution of biological nutrient removal and real-time control can be implemented in order to optimize the SBR operation.…”

Biological treatment of PAH-contaminated sediments in a Sequencing Batch Reactor

“…In the present study, the SBR technology was selected among different alternatives due to its widely proved ability in the depuration of streams containing toxic or bio-recalcitrant compounds [14][15][16][17][18]. With respect to the typical cycle of a SBR for wastewater treatment, in the Soil or Sediment Slurry SBR (SS-SBR) no settle phase is foreseen, whereas, at the end of the react phase, a known volume of slurry is withdrawn from the tank and discharged or eventually delivered to a further treatment process.…”