Jih-Gaw Lin

Co-existence of anammox and denitrification for simultaneous nitrogen and carbon removal—Strategies and issues

The discovery of anaerobic ammonium oxidation (anammox) has greatly improved the understanding of the nitrogen cycle. Anammox provides great promise for the removal of nitrogen from wastewater, containing high concentration of ammonium. However, the presence of organic carbon is considered as unfavorable to this autotrophic process, i.e. anammox. Most of the real wastewaters contain both organic carbon and nitrogen. Under this circumstance, several processes have been established primarily for the complete removal of organic carbon. Subsequently, the wastewater containing no or low organic carbon and nitrogen is treated via a variety of nitrogen removal processes. The co-existence of anammox and denitrification could be useful for the simultaneous removal of nitrogen and organic carbon in a single system rather than a sequential chain of treatment. This review addresses the microbiology, strategies, consequences and the future research challenges in the co-existence of anammox and denitrification.

Simultaneous partial nitrification, anaerobic ammonium oxidation and denitrification (SNAD) in a full-scale landfill-leachate treatment plant

The occurrence of simultaneous partial nitrification, anaerobic ammonium oxidation and denitrification (SNAD) observed in a single partially aerated full-scale bioreactor treating landfill-leachate is reported in this paper. At present, the full-scale bioreactor is treating an average leachate flow of 304 m(3)d(-1) with a sludge retention time between 12 and 18d. The average COD, NH(4)(+)-N and NO(3)(-)-N concentrations at the upstream end of the bioreactor, i.e., influent, are 554, 634 and 3 mg L(-1), respectively; whereas no NO(2)(-)-N is detected in the influent. The percentage removals of COD and NH(4)(+)-N in the bioreactor were 28% and 80%, respectively. A nitrogen mass balance approach was adopted to analyze the performance of SNAD in the full-scale bioreactor. The total nitrogen (TN) removal by combined partial nitrification and anaerobic ammonium oxidation is 68% and the heterotrophic denitrification contributes to 8% and 23% of TN and COD removals, respectively. The red granule in the bioreactor was analyzed by using fluorescence in situ hybridization and polymerase chain reaction. The results of both analytical methods confirm the presence of anaerobic ammonium oxidizing bacteria as the predominant species along with other Planctomycete-like bacteria. Overall, the SNAD process offers the simultaneous removals of nitrogen and COD in the wastewater.

Co-composting of green waste and food waste at low C/N ratio

In this study, co-composting of food waste and green waste at low initial carbon to nitrogen (C/N) ratios was investigated using an in-vessel lab-scale composting reactor. The central composite design (CCD) and response surface method (RSM) were applied to obtain the optimal operating conditions over a range of preselected moisture contents (45-75%) and C/N ratios (13.9-19.6). The results indicate that the optimal moisture content for co-composting of food waste and green waste is 60%, and the substrate at a C/N ratio of 19.6 can be decomposed effectively to reduce 33% of total volatile solids (TVS) in 12days. The TVS reduction can be modeled by using a second-order equation with a good fit. In addition, the compost passes the standard germination index of white radish seed indicating that it can be used as soil amendment.

Development of simultaneous partial nitrification, anammox and denitrification (SNAD) process in a sequential batch reactor

Simultaneous partial nitrification, anammox and denitrification (SNAD) process was developed in a sequential batch reactor (SBR) and the influence of hydraulic retention time (HRT) on the SNAD process was investigated. Around 96% NH(4)(+)-N removal and 87% COD removal were observed at 9 d HRT. Marginal decreases in the removal efficiencies were observed when the HRT was reduced to 3d or the loading rate was increased by three times. On the other hand, a drastic decrease in NH(4)(+)-N and COD removals were observed when the DO, pH and temperature were dropped shockingly. The response of the SNAD system towards the shock in substrate loading and operating conditions was evaluated by sensitivity index. Finally, the extent of total nitrogen (TN) removal by partial nitrification with anammox and denitrification was modeled using stoichiometric relationship. Modeling results indicated a TN removal of 85-87% by anammox with partial nitrification and 7-9% by denitrification.

Degradation of carbofuran in aqueous solution by ultrasound and Fenton processes: Effect of system parameters and kinetic study.

To establish an efficient oxidation process for carbofuran degradation, the effects of some operating parameters such as dosages of H(2)O(2), Fe(2+) and initial carbofuran concentrations were observed during carbofuran degradation by the ultrasound process, Fenton process and a combined ultrasound/Fenton process. The degradation kinetics of carbofuran was also examined based on the experimental data. The results show that more than 99% of the carbofuran was degraded by the ultrasound/Fenton process within short reaction time periods. Increased dosages of H(2)O(2) and Fe(2+) enhanced the degradation of carbofuran in the ultrasound and Fenton oxidation processes, but initial carbofuran concentrations decreased carbofuran degradation in both the Fenton and ultrasound/Fenton processes. The degradation kinetics of carbofuran by the three oxidation processes was found to be in accordance with first-order reaction kinetics. The results provide fundamental information about the treatment of carbofuran wastewater and/or other pesticides by the ultrasound/Fenton oxidation process.

Effect of substrate concentration on bioleaching of metal-contaminated sediment

The remediation of metal-contaminated sediment was studied using the bioleaching process with a mixed culture of sulfur-oxidizing bacteria. The effects of substrate concentration (elemental sulfur) on sediment acidification, sulfur oxidation and metal solubilization from contaminated sediment during the bioleaching process were investigated with free-cell suspensions. Sulfur concentration greater than 0.5% (w/v) was found to be inhibitory to bacterial activity and metal solubilization from sediment. The sulfate production was well described by a substrate inhibition expression and Haldanes equation. In addition, an empirical equation related to sulfur concentration was also used to describe the metal solubilization in the bioleaching process.

Partial nitrification and anammox process: A method for high strength optoelectronic industrial wastewater treatment

Completely autotrophic nitrogen removal over nitrite (CANON) process was employed in an 18 L sequencing batch reactor (SBR) for treatment of optoelectronic industrial wastewater containing high strength ammonium nitrogen (3712 ± 120 mg NH4(+) - N L(-1)). About 89% of total nitrogen and 98% of NH4(+) - N removal efficiencies were observed at the loading rate of 909 g N m(-3) d(-1) and the HRT of 4 d. A profound variation in the performance of CANON process was experienced at high DO exposure (above 1 mg L(-1)) and high nitrite concentration (above 100 mg L(-1)). Inhibition due to high DO exposure was found to be reversible phenomenon whereas the synergistic inhibition of nitrite, free ammonia and free nitrous acid was irreversible. The fluctuation of reactor temperature between 17 and 37 °C did not affect the performance of CANON system. The CANON process was stably controlled at high nitrogen loading rate for more than one month. The co-existence of aerobic and anaerobic ammonium oxidizing bacteria in the reactor was detected by The PCR analysis. About 5 fold increase in amount of anammox bacteria over a period of 258 days was confirmed from the results of qPCR on day 487.

Fast start-up, performance and microbial community in a pilot-scale anammox reactor seeded with exotic mature granules

The possibility to introduce the exotic anammox sludge to seed the pilot-scale anammox granular reactor and its fast start-up for treating high nitrogen concentration wastewater were evaluated in this study. The reactor was started up successfully in two weeks; in addition, high nitrogen removal was achieved for a long period. Stoichiometry molar ratios of nitrite conversion and nitrate production to ammonium conversion were calculated to be 1.26±0.02:1 and 0.26±0.01:1, respectively. The Stover-Kincannon model which was first applied in granular anammox process indicated that the granular anammox reactor possessed high nitrogen removal potential of 27.8 kg/m(3)/d. The anammox granules in the reactor were characterized via microscope observation and fluorescence in situ hybridization technique. Moreover, the microbial community of the granules was quantified to be composed of 91.4-92.4% anammox bacteria by real-time polymerase chain reaction. This pilot study can elucidate further information for industrial granular anammox application.

Removal of pharmaceuticals and organic matter from municipal wastewater using two-stage anaerobic fluidized membrane bioreactor.

The aim of present study was to treat municipal wastewater in two-stage anaerobic fluidized membrane bioreactor (AFMBR) (anaerobic fluidized bed reactor (AFBR) followed by AFMBR) using granular activated carbon (GAC) as carrier medium in both stages. Approximately 95% COD removal efficiency could be obtained when the two-stage AFMBR was operated at total HRT of 5h (2h for AFBR and 3h for AFMBR) and influent COD concentration of 250mg/L. About 67% COD and 99% TSS removal efficiency could be achieved by the system treating the effluent from primary clarifier of municipal wastewater treatment plant, at HRT of 1.28h and OLR of 5.65kg COD/m(3)d. The system could also effectively remove twenty detected pharmaceuticals in raw wastewaters with removal efficiency in the range of 86-100% except for diclofenac (78%). No other membrane fouling control was required except scouring effect of GAC for flux of 16LMH.

Nitrogen removal from opto-electronic wastewater using the simultaneous partial nitrification, anaerobic ammonium oxidation and denitrification (SNAD) process in sequencing batch reactor

Simultaneous partial nitrification, anaerobic ammonium oxidation and denitrification (SNAD) system was applied to treat the opto-electronic industrial wastewater in a 2.5L sequencing batch reactor. The characteristics of wastewater were low C/N ratio (≈ 0.2) with 100mg-COD/L and 567 mg NH(4)(+)-N/L. The experiment was carried out over 8 months in six different stages, where nitrogen loading rate was gradually increased from 16 g-N/m(3)d in stage I to 230 g-N/m(3)d in stage VI. The COD and nitrogen removal rates by the SNAD system reached to 28 g COD/m(3)d and 197 g NH(4)(+)-N/m(3)d, respectively in stage VI. These results showed that the SNAD system is suitable to treat wastewater containing high nitrogen pollutants with low COD level. Presence of ammonium oxidizing bacteria and anammox bacteria were confirmed by polymerase chain reaction (PCR). PCR results also indicated that Candidatus Kuenenia stuttgartiensis may be one of the dominant species in the reactor.