The anammox process for nitrogen removal from seafood processing industrial wastewater | |
| Author | Apipong Lamsam |
| Call Number | AIT Diss. no.EV-08-8 |
| Subject(s) | Sewage--Purification--Nitrogen removal Anaerobic bacteria |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. EV-08-8 |
| Abstract | Anaerobic Ammonium Oxidation (Anammox) process is a novel biological nitrogen removal process for high rate nitrogen removal. Although the knowledge on physiology, biology and chemistry of the Anammox process and bacteria is well established, researches on application to seafood processing wastewater remains unexplored. Further, the microbial niches of the Anammox process are not yet fully understood in terms of their abundance and diversity. Thus, it is necessary to further investigate microbial ecology and characteristics of Anammox bacteria in both synthetic as well as real wastewater. The objectives of this research were to investigate performance and stability of a laboratory scale Anammox gas-lift reactor using synthetic wastewater and seafood processing industrial wastewater. Furthermore, microbial ecology of Anammox biomass was also ascertained using molecular microbial technique including Fluorescence In Situ Hybridization (FISH), Polymerase Chain Reaction (PCR) and Denaturing Gradient Gel Electrophoresis (DGGE). The research was divided into three Phases including i) Phase I experiment with synthetic wastewater; ii) Phase II experiment with seafood processing wastewater; and iii) Phase III experiment on mature and inhibited (due to nitrite) Anammox biomass granule and micro bial characterization. Phase I experiment: A mature and efficient Anammox process was successfully established in a laboratory gas-lift reactor. The suitable operating conditions for Anammox process have been identified as dissolved oxygen (DO) of less than 0.1 mg 1⁻¹ and temperature of more than 29°C. Although there was an inhibition due to nitrite, the process fully recovered within one month period. During the steady state on day 164-177, the maximum nitrogen loading rate (NLR) and nitrogen removal rate (NRR) were around 2.0 and 1.9 kg N m⁻³ d⁻¹ respectively. Influent NH₄N and N0₂N concentrations were approximately 500 mg 1⁻¹. The maximum ammonium and nitrite removal rate, during the steady state, were around 90% and 98% respectively. Using FISH, Anammox bacteria have been identified as the predominant species with the relative abundance up to around 40% as compared to total bacterial population. However, several FISH probes targeting aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) did not reveal any positive signal. Analysis of microbial population using PCR-DGGE showed several uncultured bacteria with one uncultured Chloroflexi and Nitrospira sp. However, Anammox DNA was not detected using this technique. Phase II experiment: This experiment continued from Phase 1. The real wastewater was taken from a selected seafood processing industry in Samutsakom, Thailand. Characterization of wastewater from various locations in the existing wastewater treatment plant was conducted. The results revealed high COD and TKN contents in the wastewater. Hence, a pretreatment process was required to remove COD and convert half of ammonium to nitrite. These two reactions were accomplished in a novel process called "activated sludge with partial nitrification (ASIPN)". Basically, this process was an activated sludge with pH and DO controlling system to maintain partial nitrification reaction. The Anammox process received the effluent from the AS/PN process which contained low organic carbon and around 1:1 ratio of ammonium and nitrite. Complete removal of ammonium and nitrite was observed during the steady state in Phase II. Moreover, maximum NLR and NRR were around 0.4 kg N m⁻³ d⁻¹. FISH analysis of Anammox biomass revealed high abundance of Anammox bacteria around 63%. However, a small amount of halophilic Nitrosomonas (using probe NED) of 7.7% was also detected. These bacteria could be carried over from the effluent of AS/PN process where they were found in greater amount. These bacteria could be responsible for the partial nitrification reaction. No NOB was observed when other specific FISH probes were applied. DGGE profiles from Phase I and II matched exactly. Hence, there was no significant change in Anammox microbial community whether operating with synthetic or seafood processing wastewater. Partial 16S rDNA sequence of around 800 base pair was amplified from total genomic DNA of Anammox biomass using PCR primers specific to Anammox bacteria. When comparing to GenBank database, the sequence established 94% homology to a known Anammox species namely Candidatus "Brocadia fulgida" Hence, there was a high possibility of a novel Anammox species in Thailand. Phase III experiment: Microbial community of mature Anammox biomass from a Sequencing Batch Reactor (SBR) and a Continuous Stirred Tank Reactor (CSTR) was investigated using PCR-DGGE. In the inhibition study, FISH and PCR-DGGE analyses were performed. FISH revealed no significant change in Anammox bacteria relative distribution and microbial population. It was possible that Anammox bacteria maintained constant cellular rRNA contents during the inhibition by nitrite similar to the inhibition by oxygen. Hence, FISH probe targeting 16S rRNA was not a sensitive method in detecting Anammox activity. Similarly, there was no significant change in microbial ecology as observed in DOGE profiles which suggested that other bacteria in the mixed culture might not be affected by the inhibition by nitrite. However, Transmission Electron Microscope (TEM) results indicated that granule deformation and degeneration took place after the inhibition stage which confirmed the detrimental effects of high nitrite concentration to the Anammox bacteria and process |
| Year | 2008 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. EV-08-8 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Annachhatre, Ajit P. |
| Examination Committee(s) | Chongrak Polprasert ;Nowarat Coowanitwong |
| Scholarship Donor(s) | Royal Thai Government Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2008 |