A combined upflow anaerobic sludge bed, aerobic, and anoxic fixed-bed reactor system for removing tetramethylammonium hydroxide and nitrogen from light-emitting diode wastewater.

A laboratory study using a combined upflow anaerobic sludge bed (UASB) and aerobic and anoxic fixed-bed reactor system was undertaken to explore its capability for removing tetramethylammonium hydroxide (TMAH) and nitrogen from light-emitting diode wastewater. When the organic loading rate was maintained at 0.26-0.65 kg TMAH m(-3 )d(-1), the UASB reactor removed 70-100% of TMAH through methanogenesis. When the [Formula: see text] -N loading rate was maintained at 0.73-1.4 kg [Formula: see text]-N m(-3 )d(-1), the aerobic reactor oxidized 31-59% of [Formula: see text]-N to [Formula: see text]-N through nitritation. When the nitrogen loading rate was maintained at 0.42-0.75 kg N m(-3 )d(-1), the anoxic reactor removed 27-63% of nitrogen through anammox. The performance data of the combined reactor system agreed well with the stoichiometric relationships of methanogenesis, nitritation, and anammox. The batch studies showed that a higher initial TMAH concentration of up to 2520 mg L(-1) gave a higher methanogenic activity of up to 16 mL CH4 g(-1) VSS d(-1). An increase in the initial TMAH concentration of up to 500 mg L(-1) gradually decreased the activity of ammonia-oxidizing bacteria; whereas an increase in the initial TMAH concentration of up to 47 mg L(-1) imposed a marked inhibiting effect on the activity of anammox bacteria.

Removal of nitrogen from secondary effluent of a petrochemical industrial park by a hybrid biofilm-carrier reactor with one-stage ANAMMOX.

A laboratory study was undertaken to explore the capability of one-stage ANAMMOX in a hybrid biofilm-carrier reactor (HBCR) fed with petrochemical wastewater. Under favorable operating conditions in continuous-flow operations (at the dissolved oxygen level of 0.5-1.0 mg L(-1)), the average total nitrogen (TN) removal efficiency reached 62-67% and approximately 90% of TN can be removed by ANAMMOX. In batch operations of the hybrid biofilm-carrier reactor (without adding carbon substrate), the specific TN removal rate of the reactor in which both Kaldnes and nonwoven carriers were kept was two-fold higher than that of the reactor in which only nonwoven carriers were kept. This indicated that the microbial activity of thinner biofilms (Kaldnes carriers) was remarkably higher than that of thicker biofilms (nonwoven carriers). Finally, based on the 16S rRNA clone library, a cluster of ANAMMOX Candidatus Kuenenia stuttgartiensis was identified.

Biological treatment of TMAH (tetra-methyl ammonium hydroxide) in a full-scale TFT-LCD wastewater treatment plant.

This study evaluated biological treatment of TMAH in a full-scale methanogenic up-flow anaerobic sludge blanket (UASB) followed by an aerobic bioreactor. In general, the UASB was able to perform a satisfactory TMAH degradation efficiency, but the effluent COD of the aerobic bioreactor seemed to increase with an increased TMAH in the influent wastewater. The batch test results confirmed that the UASB sludge under methanogenic conditions would be favored over the aerobic ones for TMAH treatment due to its superb ability of handling high strength of TMAH-containing wastewaters. Based on batch experiments, inhibitory chemicals present in TFT-LCD wastewater like surfactants and sulfate should be avoided to secure a stable methanogenic TMAH degradation. Finally, molecular monitoring of Methanomethylovorans hollandica and Methanosarcina mazei in the full-scale plant, the dominant methanogens in the UASB responsible for TMAH degradation, may be beneficial for a stable TMAH treatment performance.