The start-up period of Anammox systems is still a big challenge due to the unavailability of large volumes of slowly growing Anammox seed locally in most countries. This study aims to evaluate the effects of seeding strategy on the start-up and enrichment period of Anammox systems by monitoring both process performance and microbial population dynamics. Two different seeding strategies, the use of mixed activated sludge culture from a local STP and the use of enriched Anammox culture transported from abroad, were comparatively studied in SBR systems operated for 410 days. The enriched Anammox seed from abroad inhibited seriously during transportation. Anammox activity re-started after 195 days' recovery period. An active Anammox culture was successfully enriched within 95 days from a local activated sludge source without seeding any Anammox. The Anammox population reached levels of 1011 copies/ng at the end of 410 days' enrichment period. Based on FISH, Ca. Brocadia anammoxidans and Ca. Scalindua species were dominant in the enriched culture. The maximum TNRR was observed as 430 mg N/day. DGGE analyses revealed a drastic change in the microbial community (56%) with Anammox enrichment. Phylogenetic analysis demonstrated a significant decrease in phylotype Proteobacteria and increase in phylotypes Planctomycetes, Chloroflexi and Acidobacteria with enrichment.

Process dynamics in Anammox systems were evaluated through continuous monitoring of pH, oxidation reduction potential (ORP) and conductivity in two separate newly started-up sequencing batch reactors, one seeded with an enriched Anammox sludge and the other seeded with mixed activated sludge. The pH and ORP profiles exhibited characteristic patterns depending on the process dynamics during early start-up, start-up and enrichment phases of the operational period of 410 days. The simultaneously continuing processes of the start-up period showed apparent indicative trend lines in pH and ORP profiles. Conductivity profiles were consistent with the process dynamics in all phases. During the enrichment phase, conductivity decreases could quantitatively be related to process removal efficiencies and all real-time profiles exhibited specific break-points which coincided with the end of Anammox in each cycle. The end of Anammox was observed as an 'apex' on pH profiles and a 'valley' on ORP profiles. The 'apex' and 'valley' points exactly coincided with the end point of the linear decrease in the conductivity profiles. The overall findings suggested a great potential in using real-time pH, ORP and conductivity measurements for quick and reliable monitoring of Anammox systems during start-up and enrichment periods.

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Process dynamics in Anammox systems were evaluated by continuous monitoring of pH, ORP and conductivity values in two newly started-up sequencing batch reactors, the one seeded with an enriched Anammox sludge from the first worldwide full-scale Anammox reactor in the Netherlands and the other seeded with mixed activated sludge from a local sewage treatment plant in Istanbul, Turkey. During early start-up, start-up and enrichment phases of 410-day operational period, pH and ORP profiles exhibited characteristic patterns depending on the process dynamics prevailing in the reactors. The simultaneously ongoing processes (e.g., denitrification and Anammox) of start-up period that could not easily be differentiated via changes in nitrogen species showed apparent indicative trendlines on pH and ORP profiles. In all phases of both reactor systems, conductivity profiles were consistent with the process dynamics. But, conductivity decreases observed during early start-up and start-up periods could not quantitatively be related with process removal efficiencies. During enrichment phase, however, rough quantitative correlation between the relative change in conductivity values and nitrogen species concentrations was identified in both reactor systems.In enrichment phase, all real-time measurement profiles exhibited specific break-points coincided with the end of Anammox process in each cycle. The end of Anammox process was observed as an "apex" on pH profiles and a"valley" on ORP profiles. The "apex" and valley" points exactly coincided with the end point of linear decrease on conductivity profiles.The overall findings demonstrated that process dynamics in a newly started-up Anammox reactor can successfully be managed via real-time pH and ORP measurements which allow quick and reliable differentiation of simultaneously ongoing processes especially during early start-up period. For the successfully started-up SBR type Anammox reactors, a control strategy based on real -time pH, ORP and conductivity measurements might enable self-adjustment of cycle time depending on the fluctuations in influent wastewater strength to achieve consistent effluent quality.