[Role of Anammox Bacteria in Removal of Nitrogen Compounds from Wastewater].

The review deals with the unique microbial group responsible for anaerobic ammonium oxidation with nitrite (anammox), and with the role of this process in development of the biotechnology for removal of nitrogen compounds from wastewater. The history of the study of this process is briefly related. Up-to date knowledge on the intracellular organization, energy metabolism, growth stoichiometry, and physiology of anammox bacteria is described, and the main methods for cultivation of these microorganisms are characterized. Special attention is paid to the problems associated with practical application of anammox bacteria, which result from their extremely slow growth, the absence of pure cultures, and the interaction with other microbial groups.

[Candidatus "Jettenia moscovienalis" sp. nov., a New Species of Bacteria Carrying out Anaerobic Ammonium Oxidation].

A new species of bacteria oxidizing ammonium with nitrite under anoxic conditions was isolated from the activated sludge of a semi-industrial bioreactor treating digested sludge of the Kuryanovo wastewater treatment plant (Moscow, Russia). Physiological, morphological, and molecular genetic characterization of the isolate was carried out. The cells were ovoid (-0.5 x 0.8 µm), with the intracellular membrane structures characteristic of anammox bacteria (anammoxosome and paryphoplasm); unlike other anammox bacteria, it possessed extensive intracellular membrane structures located in layers parallel to the cytoplasmic membrane, but never close to the anammoxosome. The cells formed aggregates 5-28 µm in diameter and readily attached to solid surfaces. The cells were morphologically labile, easily plasmolyzed, and lost their content. Doubling time was 28 days, µ(max) = 0.025 day(-1); optimal temperature and pH for growth were 20-45 degrees C and 8.0, respectively. Phylogenetic analysis of the 16S rRNA gene sequences suggested its classification as a new species of the candidate genus Jettenia (order Planctomycetales). The name Candidatus "Jettenia moscovienalis" sp. nov. was proposed for the new bacterium.

[Microbial composition of the activated sludges of the Moscow wastewater treatment plants].

The contribution of the major technologically important microbial groups (ammonium- and nitrite-oxidizing, phosphate-accumulating, foam-inducing, and anammox bacteria, as well as planctomycetes and methanogenic archaea) was characterized for the aeration tanks of the Moscow wastewater treatment facilities. FISH investigation revealed that aerobic sludges were eubacterial communities; the metabolically active archaea contributed insignificantly. Stage II nitrifying microorganisms and planctomycetes were significant constituents of the bacterial component of activated sludge, with Nitrobacter spp. being the dominant nitrifier. No metabolically active anammox bacteria were revealed in the sludge from aeration tanks. The sludge from the aeration tanks using different wastewater treatment technologies were found to differ in characteristics. Abundance of the nitrifying and phosphate-accumulating bacteria in the sludges generally correlated with microbial activity, in microcosms and with efficiency of nitrogen and phosphorus removal from wastewater. The highest microbial numbers and activity were found in the sludges of the tanks operating according to the technologies developed in the universities of Hanover and Cape Town. The activated sludge from the Novokur yanovo facilities, where abundant growth of filamentous bacteria resulted in foam formation, exhibited the lowest activity The group of foaming bacteria included Gordonia spp. and Acinetobacter spp., utilizing petroleum and motor oils, Sphaerotilus spp. utilizing unsaturated fatty acids, and Candidatus 'Microthrix parvicella'. Thus, the data on abundance and composition of metabolically active microorganisms obtained by FISH may be used for the technological control of wastewater treatment.

[A novel bacterium carrying out anaerobic ammonium oxidation in a reactor for biological treatment of the filtrate of wastewater fermented residue].

A new genus and species of bacteria capable of ammonium oxidation under anaerobic conditions in the presence of nitrite is described. The enrichment culture was obtained from the Moscow River silt by sequential cultivation in reactors with selective conditions for anaerobic ammonium oxidation. Bacterial cells were coccoid, -0.4 x 0.7 mm, with the intracellular membrane structures typical of bacteria capable of anaerobic ammonium oxidation (anammoxosome and paryphoplasm). The cells formed aggregates 5-25 µm in diameter (10 µm on average). They were readily adhered to solid surfaces. The cells were morphologically labile, they easily lost their content and changed their morphology during fixation for electron microscopy. The organism was capable of ammonium oxidation with nitrite. The semisaturation constants Ks for nitrite and ammonium were 0.38 mg N-NO2/L and 0.41 mg N-NH4/L, respectively. The maximal nitrite concentrations for growth were 90 and 75 mg N-NO2/L for single and continuous application, respectively. The doubling time was 32 days, µ(max) = 0.022 day(-1), the optimal temperature and pH were 20 degrees C and 7.8-8.3, respectively. According to the 16S rRNA gene sequencing, the bacterium was assigned to a new genus and species within the phylum Planctomycetes. The proposed name for the new bacterium is Candidatus Anammoximicrobium moscowii gen. nov., sp. nov. (a microorganisms carrying out anaerobia ammonium oxidation, isolated in the Moscow region).

Comparison of different thickening methods for active biomass recycle for anaerobic digestion of wastewater sludge.

The effect of returning solids to the digester, after one of three thickening processes, on volatile solids reduction (VSR) and gas production was investigated. Three different thickening methods were compared: centrifugation, flotation and gravitational sedimentation. The amount and activity of retained biomass in thickened recycled sludge affected the efficiency of digestion. Semi-continuous laboratory digesters were used to study the influence of thickening processes on thermophilic sludge digestion efficiency. Centrifugation was the most effective method used and caused an increase of VSR from 43% (control) up to 70% and gas generation from 0.40 to 0.44 L g(-1) VS. Flotation and gravitational sedimentation ways of thickening appeared to be less effective if compared with centrifugation. These methods increased VSR only by up to 65 and 51%, respectively and showed no significant increase of gas production. The dewatering capacity of digested sludge, as measured by its specific resistance to filtration, was essentially better for the sludge digested in the reactors with centrifugated and settled recycle. The VS concentration of recycle (g L(-1)), as reflecting the amount of retained biomass, appeared to be one of the most important factors influencing the efficiency of sludge digestion in the recycling technology.

Anaerobic thermophilic digestion of sewage sludge with a thickened sludge recycle.

The process of anaerobic thermophilic digestion of municipal wastewater sludge with a recycled part of thickened digested sludge, was studied in semi-continuous laboratory digesters. This modified recycling process resulted in increased solids retention time (SRT) with the same hydraulic retention time (HRT) as compared with traditional digestion without recycling. Increased SRT without increasing of HRT resulted in the enhancement of volatile substance reduction by up to 68% in the reactor with the recycling process compared with 34% in a control conventional reactor. Biogas production was intensified from 0.3 L/g of influent volatile solids (VS) in the control reactor up to 0.35 L/g VS. In addition, the recycling process improved the dewatering properties of digested sludge.

[Gastric function after organ-preserving surgery in stenosing pyloroduodenal ulcers]. / Funktsiia zheludka posle organosokhraniaiushchikh operatsii pri stenoziruiushchikh piloroduodenal'nykh iazvakh.

The article analyses the results of organ-preserving operations in 170 patients with duodenal ulcers complicated by stenosis of various stages. The motor and secretory activity of the stomach, the terms of ulcer healing after the operation, and the character of changes in the dimensions of the stomach following surgical interventions were studied. On the basis of the study the authors conclude that organ-preserving operations may be conducted in ulcerative pyloroduodenal stenosis, and in the decompensated form.

[Prevention of errors and complications of organ-sparing operations in the treatment of duodenal ulcer]. / Profilaktika oshibok i oslozhnenii organosokhraniaiushchikh operatsii pri lechenii iazvennoi bolezni dvenadtsatiperstnoi kishki.

Based on an analysis of complications of organ-preserving operations on 300 patients with duodenal ulcers the authors make a conclusion that the character and severity of complications after organ-preserving operations are of much more benign nature than those after gastric resections. To reduce the incidence of complications the authors propose to use a wider access at the expense of dissection of the xiphoid process, to reject of Nissen fundoplication in favour of simple restoration of the damaged ligamentous apparatus of the stomach.

[Organ-sparing operations in pyloroduodenal stenosis caused by peptic ulcer]. / Organosokhraniaiushchie operatsii pri piloroduodenal'nom iazvennom stenoze.

An experience with the treatment of 106 patients with pyloroduodenal stenosis of ulcerous etiology by vagotomy with draining operations has shown high efficiency of these measures resulting in lower rate of postoperative lethality. Selective proximal and stem vagotomy does not aggravate gastric atony in patients with stenosis. Electro-stimulation was found to be an effective method of treatment of this complication in the postoperative period of patients with gastric atony.