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This paper corresponds to the second part of a study aiming to establish the best conditions to start-up decentralised membrane bioreactors. The first part focused on the impact of different operational parameters on the start-up, whereas this second part aims to find a substitute for activated sludge to serve as initial inoculum. Both low powdered activated carbon addition and Alumin 7 (alkaline coagulant) demonstrated a low performance in terms of filterability and operation. In turn, ferrous chloride (FeCl2), due to its ability to coagulate soluble and colloidal matter, was able to create a cake layer composed of large coagulated particles acting as a prefilter. Additionally, the combination of wastewater plus FeCl2 allowing sufficient contact time before the filtration starts has demonstrated to be the best way to start-up decentralised membrane bioreactor using this additive. Eventhough some drawbacks are associated with its high acidity, i.e. low pH, high conductivity and low NH4+ -N removal, the excellent filterabilities observed and the possibility to create a cake layer from "zero-biomass" convert this additive as a possible substitute for activated sludge. This is supported by particle size distribution measurements suggesting that the negative effects of fine particles are outweighed by the possibility of creating a cake layer that impedes pore blocking. [ABSTRACT FROM AUTHOR]

Two lab-scale plug flow activated sludge reactors were run in parallel for 4 months at 30 and 55°C. Research focussed on: (1) COD (chemical oxygen demand) removal, (2) effluent turbidity at both temperatures, (3) the origin of effluent colloidal material and (4) the possible role of protozoa on turbidity levels. Total COD removal percentages over the whole experimental period were 66±7% at 30°C and 53±11% at 55°C. Differences in total COD removal between both systems were due to less removal of soluble and colloidal COD at 55°C compared to the reference system. Thermophilic effluent turbidity was caused by a combination of influent colloidal particles that were not effectively retained in the sludge flocs, and erosion of the thermophilic activated sludge itself, as shown by denaturing gradient gel electrophoresis (DGGE) profiles. DGGE analysis of PCR-amplified 16S rDNA fragments from mesophilic and thermophilic sludge differed, indicating that different microbial communities were present in the two reactor systems. The effects of protozoal grazing on the effluent turbidity of both reactors was negligible and thus could not account for the large turbidity differences observed. [ABSTRACT FROM AUTHOR]

Pre-treatments for waste activated sludge (WAS) are, in most cases, an attempt to increase the biodegradation and/or improve hydrolysis rate of WAS after anaerobic digestion. This review presents an extensive analysis of WAS pre-treatments effectiveness focusing on increasing the biodegradability. In the first part of the review, WAS is considered as a cluster of organic components: proteins, carbohydrates, humic substances and cells. Based on this breakdown into components, the effect of different pre-treatments on each component (and in combination) is described. Also, possible reasons for the contradictory results frequently found among different studies dealing with the same pre-treatment are included. In the second part, the review describes the effects on volatile solids removal by digestion after pre-treatment and on the dewaterability of the final digestate. The energy balance and potential limiting factors for each pre-treatment are also taken into account. From the published works it is concluded that some pre-treatment techniques, such as thermal hydrolysis, thermal phased anaerobic digestion and low-temperature pre-treatment are effective ways to increase energy production and to improve other sludge properties, such as dewatering. However, these techniques are very energy intensive and require a large capital outlay, so research on milder pre-treatment techniques is valuable., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Fermentation and anaerobic digestion of organic waste and wastewater is broadly studied and applied. Despite widely available results and data for these processes, comparison of the generated results in literature is difficult. Not only due to the used variety of process conditions, but also because of the many different growth media that are used. Composition of growth media can influence biogas production (rates) and lead to process instability during anaerobic digestion. To be able to compare results of the different studies reported, and to ensure nutrient limitation is not influencing observations ascribed to process dynamics and/or reaction kinetics, a standard protocol for creating a defined growth medium for anaerobic digestion and mixed culture fermentation is proposed. This paper explains the role(s) of the different macro- and micronutrients, as well as the choices for a growth medium formulation strategy. In addition, the differences in nutrient requirements between mesophilic and thermophilic systems are discussed as well as the importance of specific trace metals regarding specific conversion routes and the possible supplementary requirement of vitamins. The paper will also give some insight into the bio-availability and toxicity of trace metals. A remarkable finding is that mesophilic and thermophilic enzymes are quite comparable at their optimum temperatures. This has consequences for the trace metal requirements of thermophiles under certain conditions. Under non-limiting conditions, the trace metal requirement of thermophilic systems is about 3 times higher than for mesophilic systems., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Kinetic parameters describing growth and decay of mesophilic (30 degrees C) and thermophilic (55 degrees C) aerobic biomass were determined in continuous and batch experiments by using oxygen uptake rate measurements. Biomass was cultivated on a single soluble substrate (acetate) in a mineral medium. The intrinsic maximum growth rate ( micro (max)) at 55 degrees C was 0.71+/-0.09 h(-1), which is 1.5 times higher than the micro (max) at 30 degrees C (0.48+/-0.11 h(-1)). The biomass decay rates increased from 0.004 h(-1) at 30 degrees C to 0.017 h(-1) at 55 degrees C. Monod constants were very low for both types of biomass: 9+/-2 mg chemical oxygen demand (COD) l(-1)at 30 degrees C and 3+/-2 mg COD l(-1)at 55 degrees C. Theoretical biomass yields were similar at 30 and 55 degrees C: 0.5 g biomass COD (g acetate COD)(-1). The observed biomass yields decreased under both temperature conditions as a function of the cell residence time. Under thermophilic conditions, this effect was more pronounced due to the higher decay rates, resulting in lower biomass production at 55 degrees C compared to 30 degrees C.

Anaerobic treatment of a volatile fatty acid (VFA) mixture was investigated under psychrophilic (3 to 8 degrees C) conditions in two laboratory-scale expanded granular sludge bed reactor stages in series. The reactor system was seeded with mesophilic methanogenic granular sludge and fed with a mixture of VFAs. Good removal of fatty acids was achieved in the two-stage system. Relative high levels of propionate were present in the effluent of the first stage, but propionate was efficiently removed in the second stage, where a low hydrogen partial pressure and a low acetate concentration were advantageous for propionate oxidation. The specific VFA-degrading activities of the sludge in each of the modules doubled during system operation for 150 days, indicating a good enrichment of methanogens and proton-reducing acetogenic bacteria at such low temperatures. The specific degradation rates of butyrate, propionate, and the VFA mixture amounted to 0.139, 0.110, and 0.214 g of chemical oxygen demand g of volatile suspended solids-1 day-1, respectively. The biomass which was obtained after 1.5 years still had a temperature optimum of between 30 and 40 degrees C.

Objective: To study the localisation of treponemes and to analyse the inflammatory infiltrate in biopsy specimens from patients with primary or secondary syphilis, or early infectious yaws., Materials and Methods: Skin biopsies originating from human lesions of primary (29x) or secondary (15x) syphilis (Rotterdam), or early yaws (18x) (West Sumatra) were studied. Different histochemical and immunohistochemical detection methods were used in this study., Results and Conclusion: The histochemical silver staining method according to Steiner revealed the presence of T. pallidum in all cases of primary syphilis studied. In 10 out of 14 cases of secondary syphilis, treponemes were demonstrated. With an immunofluorescence staining technique (IF) using anti-T. pallidum antiserum raised in rabbits (a-Tp), T. pallidum was demonstrated in 28 out of 29 cases of primary syphilis, and in 14 out of 14 studied cases of secondary syphilis. The silver staining method and IF showed identical localisations of T. pallidum (mainly in the dermal-epidermal junction zone or throughout the dermis). Using a-Tp antiserum in the indirect immunofluorescence technique, T. pertenue could be demonstrated in the dermis more often than with Steiner silver staining. However, epidermotropism of T. pertenue in yaws specimens was remarkable, compared with more mesodermotropism of T. pallidum; numbers of T. pertenue in the dermis were limited in all specimens. The dermal inflammatory infiltrate in primary and secondary syphilis was composed mainly of lymphocytes and plasma cells. In most cases more T (CD3 positive) cells than B (CD22 positive) cells were present. Regarding T cell subpopulations, in primary syphilis, T helper/inducer (CD4 positive) cells predominated in 86% of cases. In secondary syphilitic lesions, numbers of T helper/inducer cells were less frequent than or equal to T-suppressor/cytotoxic (CD8 positive) cells in 60% of cases. Remarkably, in yaws specimens the inflammatory infiltrate consisted mainly of IgG, but also IgA and IgM producing plasma cells. T or B lymphocytes were scarce, which is in sharp contrast with findings in syphilitic lesions.

Thermophilic propionate-oxidizing, proton-reducing bacteria were enriched from the granular methanogenic sludge of a bench-scale upflow anaerobic sludge bed reactor operated at 55 degrees C with a mixture of volatile fatty acids as feed. Thermophilic hydrogenotrophic methanogens had a high decay rate. Therefore, stable, thermophilic propionate-oxidizing cultures could not be obtained by using the usual enrichment procedures. Stable and reproducible cultivation was possible by enrichment in hydrogen-pregrown cultures of Methanobacterium thermoautotrophicum DeltaH which were embedded in precipitates of FeS, achieved by addition of FeCl(2) to the media. The propionate-oxidizing bacteria formed spores which resisted pasteurization for 30 min at 90 degrees C or 10 min at 100 degrees C. Highly purified cultures were obtained with either M. thermoautotrophicum DeltaH or Methanobacterium thermoformicicum Z245 as the syntrophic partner organism. The optimum temperature for the two cultures was 55 degrees C. Maximum specific growth rates of cultures with M. thermoautotrophicum DeltaH were somewhat lower than those of cultures with M. thermoformicicum Z245 (0.15 and 0.19 day, respectively). Growth rates were even higher (0.32 day) when aceticlastic methanogens were present as well. M. thermoautotrophicum DeltaH is an obligately hydrogen-utilizing methanogen, showing that interspecies hydrogen transfer is the mechanism by which reducing equivalents are channelled from the acetogens to this methanogen. Boundaries of hydrogen partial pressures at which propionate oxidation occurred were between 6 and 34 Pa. Formate had a strong inhibitory effect on propionate oxidation in cultures with M. thermoautotrophicum. Inhibition by formate was neutralized by addition of the formate-utilizing methanogen or by addition of fumarate. Results indicate that formate inhibited succinate oxidation to fumarate, an intermediate step in the biochemical pathway of propionate oxidation.

Upflow anaerobic sludge blanket bioreactor granules were used as an experimental model microbial consortium to study the dynamics and distribution of methanogens. Immunologic methods revealed a considerable diversity of methanogens that was greater in mesophilic granules than in the same granules 4 months after a temperature shift from 38 to 55 degrees C. During this period, the sizes of the methanogenic subpopulations changed with distinctive profiles after the initial reduction caused by the shift. Methanogens antigenically related to Methanobrevibacter smithii PS and ALI, Methanobacterium hungatei JF1, and Methanosarcina thermophila TM1 increased rapidly, reached a short plateau, and then fell to lower concentrations that persisted for the duration of the experiment. A methanogen related to Methanogenium cariaci JR1 followed a similar profile at the beginning, but it soon diminished below detection levels. Methanothrix rods weakly related to the strain Opfikon increased rapidly, reaching a high-level, long-lasting plateau. Two methanogens related to Methanobrevibacter arboriphilus AZ and Methanobacterium thermoautotrophicum DeltaH emerged from very low levels before the temperature shift and multiplied to attain their highest numbers 4 months after the shift. Histochemistry and immunohistochemistry revealed thick layers, globular clusters, and lawns of variable density which were distinctive of the methanogens related to M. thermoautotrophicum DeltaH, M. thermophila TM1, and M. arboriphilus AZ and M. soehngenii Opfikon, respectively, in thin sections of granules grown at 55 degrees C for 4 months. Mesophilic granules showed a different pattern of methanogenic subpopulations.