Anaerobic ammonium oxidation process in an upflow anaerobic sludge blanket reactor with granular sludge selected from an anaerobic digestor

Identification of bacterial communities in conventional wastewater treatment sludge to inform inoculation of the anammox process

This study uses 16 S rRNA gene pyrosequencing for the identification of a vast number of wastewater bacterial communities to investigate the evolution of bacterial communities in the Anammox process. Four lab-scale Anammox reactors inoculated with different conventional wastewater treatment sludge (activated sludge, livestock wastewater treatment sludge, denitrification sludge, and anaerobic digestion sludge) were operated under identical operating conditions for more than 400 days. The phylum Planctomycetes was present in all seeds of conventional sludge with a relative abundance of 1-3%. In particular, the known Anammox bacteria Candidatus Brocadia was found in the seed of the denitrification sludge. The reactor inoculated with denitrification sludge demonstrated the most effective nitrogen removal of ∼80% with successful cultivation of Anammox bacteria. This study found that the performance of the Anammox process is related to the presence of Nitrospira genus (nitrite-oxidizing bacteria) and that symbiotic association with other functional groups can lead to nitrogen removal. The outcomes of this study can provide vital insight into the study of microbial ecology for the cultivation of Anammox bacteria.

Purification of the key enzyme complexes of the anammox pathway from DEMON sludge

Anaerobic Ammonium Oxidation ("anammox") is a bacterial process in which nitrite and ammonium are converted into nitrogen gas and water, yielding energy for the cell. Anammox is an important branch of the global biological nitrogen cycle, being responsible for up to 50% of the yearly nitrogen removal from the oceans. Strikingly, the anammox process uniquely relies on the extremely reactive and toxic compound hydrazine as a free intermediate. Given its global importance and biochemical novelty, there is considerable interest in the enzymes at the heart of the anammox pathway. Unfortunately, obtaining these enzymes in sufficiently large amounts for biochemical and structural studies is problematic, given the slow growth of pure cultures of anammox bacteria when high cell densities are required. However, the anammox process is being applied in wastewater treatment to remove nitrogenous waste in processes like DEamMONification (DEMON). In plants using such processes, which rely on a combination of aerobic ammonia-oxidizers and anammox organisms, kilogram amounts of anammox bacteria-containing sludge are readily available. Here, we report a protein isolation protocol starting from anammox cells present in DEMON sludge from a wastewater treatment plan that readily yields pure preparations of key anammox proteins in the tens of milligrams, including hydrazine synthase HZS and hydrazine dehydrogenase (HDH), as well as hydroxylamine oxidoreductase (HAO). HDH and HAO were active and of sufficient quality for biochemical studies and for HAO, the crystal structure could be determined. The method presented here provides a viable way to obtain materials for the study of proteins not only from the central anammox metabolism but also for the study of other exciting aspects of anammox bacteria, such as for example, their unusual ladderane lipids.

An innovative U-shaped sludge bed anammox process for nitrogen removal

In this study, we proposed an innovative U-shaped sludge bed reactor which could be a cost effective and simplified approach for the operation of an anammox reactor. The performance for nitrogen removal and the composition of bacterial communities were investigated for about 500 days of operation. The nitrogen removal rate could be approximately 85% when the total nitrogen loading rate was about 0.54 kg N/m³/d. The 16S rRNA gene pyrosequencing analysis of the bacterial community determined that Betaproteobacteria (class level) of the ammonia-oxidizing bacteria (AOB) community, Nitrospira (genus level) of the nitrite-oxidizing bacteria (NOB) community, and Brocadia (genus level) of the anammox bacteria community simultaneously coexisted in the reactor sludge. These results demonstrated that simultaneous growth and coexistence of AOB, NOB, and anammox were capable within the reactor. Furthermore, a mathematical modeling system was developed to simulate the nitrification and anammox processes. The model simulation showed that the oxygen was rapidly depleted and that led to a drop in the activity of AOB and NOB, then the growth of anammox bacteria started under anaerobic conditions.

Microbial monitoring of ammonia removal in a UASB reactor treating pre-digested chicken manure with anaerobic granular inoculum

Performance and microbial community dynamics in an upflow anaerobic sludge bed (UASB) reactor coupled with anaerobic ammonium oxidizing (Anammox) treating diluted chicken manure digestate (Total ammonia nitrogen; TAN=123±10mg/L) were investigated for a 120-d operating period in the presence of anaerobic granular inoculum. Maximum TAN removal efficiency reached to above 80% with as low as 20mg/L TAN concentrations in the effluent. Moreover, total COD (tCOD) with 807±215mg/L in the influent was removed by 60-80%. High-throughput sequencing revealed that Proteobacteria, Actinobacteria, and Firmicutes were dominant phyla followed by Euryarchaeota and Bacteroidetes. The relative abundance of Planctomycetes significantly increased from 4% to 8-9% during the late days of the operation with decreased tCOD concentration, which indicated a more optimum condition to favor ammonia removal through anammox route. There was also significant association between the hzsA gene and ammonia removal in the UASB reactor.

Start-up of low-temperature anammox in UASB from mesophilic yeast factory anaerobic tank inoculum

Robust start-up of the anaerobic ammonium oxidation (anammox) process from non-anammox-specific seeding material was achieved by using an inoculation with sludge-treating industrial [Formula: see text]-, organics- and N-rich yeast factory wastewater. N-rich reject water was treated at 20°C, which is significantly lower than optimum treatment temperature. Increasing the frequency of biomass fluidization (from 1-2 times per day to 4-5 times per day) through feeding the reactor with higher flow rate resulted in an improved total nitrogen removal rate (from 100 to 500 g m(-3)d(-1)) and increased anammox bacteria activity. As a result of polymerase chain reaction (PCR) tests, uncultured planctomycetes clone 07260064(4)-2-M13-_A01 (GenBank: JX852965) was identified from the biomass taken from the reactor. The presence of anammox bacteria after cultivation in the reactor was confirmed by quantitative PCR (qPCR); an increase in quantity up to ∼2×10(6) copies g VSS(-1) during operation could be seen in qPCR. Statistical modelling of chemical parameters revealed the roles of several optimized parameters needed for a stable process.

ANAMMOX process start up and stabilization with an anaerobic seed in Anaerobic Membrane Bioreactor (AnMBR)

ANaerobic AMMonium OXidation (ANAMMOX) process, an advanced biological nitrogen removal alternative to traditional nitrification--denitrification removes ammonia using nitrite as the electron acceptor without oxygen. The feasibility of enriching anammox bacteria from anaerobic seed culture to start up an Anaerobic Membrane Bioreactor (AnMBR) for N-removal is reported in this paper. The Anammox activity was established in the AnMBR with anaerobic digester seed culture from a Sewage Treatment Plant in batch mode with recirculation followed by semi continuous process and continuous modes of operation. The AnMBR performance under varying Nitrogen Loading Rates (NLR) and HRTs is reported for a year, in terms of nitrogen transformations to ammoniacal nitrogen, nitrite and nitrate along with hydrazine and hydroxylamine. Interestingly ANAMMOX process was evident from simultaneous Amm-N and nitrite reduction, consistent nitrate production, hydrazine and hydroxylamine presence, notable organic load reduction and bicarbonate consumption.

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.

Start-up and stabilization of an Anammox process from a non-acclimatized sludge in CSTR

Development of an Anammox (anaerobic ammonium oxidation) process using non-acclimatized sludge requires a long start-up period owing to the very slow growth rate of Anammox bacteria. This article addresses the issue of achieving a shorter start-up period for Anammox activity in a well-mixed continuously stirred tank reactor (CSTR) using non-acclimatized anaerobic sludge. Proper selection of enrichment conditions and low stirring speed of 30 +/- 5 rpm resulted in a shorter start-up period (82 days). Activity tests revealed the microbial community structure of Anammox micro-granules. Ammonia-oxidizing bacteria (AOB) were found on the surface and on the outer most layers of granules while nitrite-oxidizing bacteria (NOB) and Anammox bacteria were present inside. Fine-tuning of influent NO2(-)/NH4+ ratio allowed Anammox activity to be maintained when mixed microbial populations were present. The maximum nitrogen removal rate achieved in the system was 0.216 kg N/(m(3) day) with a maximum specific nitrogen removal rate of 0.434 g N/(g VSS day). During the study period, Anammox activity was not inhibited by pH changes and free ammonia toxicity.