Deammonification involves the combined application of aerobic and anoxic ammonium-oxidizing bacteria (AerAOB & AnAOB) and allows to treat wastewaters with a high ammonium concentration in a sustainable and cost-efficient way. So far, it could take more than one year to start up the process, even with the addition of AnAOB enriched inocula. In contrast, we started up a deammonifying reactor for the treatment of sludge digestate in less than four months without any AnAOB enriched inoculum. In a single sequencing batch reactor (SBR) of 3 m(3), nitritation and anammox were performed without nitrite accumulation. Larger biomass aggregates (>1.0 mm) had a typical reddish colour, but FISH also showed that small aggregates (<0.25 mm) contained a considerable amount of AnAOB. The AerAOB were related to Nitrosomonas halophila, N. eutropha and N. halophila, and the AnAOB to "Candidatus Kuenenia & Brocadia", as shown by FISH. Our results show that the deammonification inoculum does not play an important role, and that the AnAOB can quickly develop under the proper aerational conditions. Nitrogen was removed stably at high nitrogen loading rates (740 mg N/L/d) and removal efficiency (90%).

Surveya Wastewater Treatment, To assess bulking in French wastewater treatment plants we developed a three-topic Water Quality and Hydrology approach, including analysis of i) technical assistance annual reports, ii) a questionnaire, Research Unit, Cemagref, and iii) microscopic sample observations. A seasonal effect was very apparent on the Parc de Tourvoie BP 44, F-92163 Antony cedex, France average SVI (mL/g). Three situations appear to promote bulking according to statistical analysis and operators' comments: i) low-organic loading or rapid variation in organic loading, ii) raw sewage dilution or hydraulic loading variation, iii) rapid high-organic loading. Phosphorus removal by metallic salt addition leads to an average SVI reduction of 40 mL/g. Two situations in the sludge treatment process, which call for improvement, are: Ϫ The maintaining a high MLSS concentration in the aeration tank due to the limitation of sludge evacuation, Ϫ When storing sludge for several days or weeks in sludge thickening tank, thereby favoring the formation of septic compounds, which are subsequently reintroduced in the influent. Our study highlights Type 0092 as the most frequent filamentous microorganism observed followed by Microthrix parvicella. Thiothrix spp. ranks third. Blähschlamm und Schwimmschlamm in Frankreich: Umfrage in 1999؊2001Zur Einschätzung von Blähschlammereignissen in französischen Kläranlagen entwickeln wir einen Ansatz mit drei Schwerpunkten: Analyse der Jahresberichte der Betriebe, Fragebogenaktion und mikroskopische Untersuchung von Schlammproben. Es zeigte sich deutlich ein jahreszeitlicher Effekt beim durchschnittlichen Schlammindex SVI (mL/g). Drei Situationen scheinen Blähschlamm förderlich zu sein, wie sowohl die statistische Analyse als auch die Betriebsdaten zeigen: Unterbelastung oder schwankende organische Belastung, Verdünnung des Rohabwassers oder schwankende hydraulische Belastung, rasch eintretende organische Überbelastung. Phosphorentfernung durch Zugabe von Metallsalzen führt zu einer durchschnittlichen Reduzierung des SVI auf 40 mL/g. Verbesserungswürdig ist die Schlammbehandlung: Schwierigkeiten bei der Schlammentsorgung führen dazu, dass mit hohem Schlammgehalt im Belebungsbecken gefahren wird oder Schlamm über Tage oder Wochen gelagert werden muss, was Faulprozesse fördert. Unsere Untersuchung bestätigt, dass Typ 0092 an erster Stelle der Blähschlammverursacher steht, vor Microthrix parvicella. Thiothrix spp. belegt Rang 3.

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The removal of nitrogen represents an important treatment objective for the processing of wastewaters. One significant contributor to the influent nitrogen loads is the recycled digester supernatant, typical after some form of dewatering such as belt filter press or centrifuge. Conventional methods of nitrification and denitrification are then widely implemented in the main liquid line. An interesting alternative for the high ammonium concentrated waters is the 'nitrate shunt' process, which allows treatment of this side-stream separately. This article presents the results obtained on an industrial pilot plant processing supernatant coming from digested biosolids and implementing a nitrate shunt treatment. Issues related to installation and biomass acclimation processes as well as regulation of oxygen and denitrification are discussed. Chemical dosage and FISH analysis were performed during the pilot study experiments. Almost one year of operation experience on site allows us to validate the process and discuss design considerations.