scholarly journals Thermal and chemical disinfection of water and biofilms: only a temporary effect in regard to the autochthonous bacteria

2021 ◽  
Author(s):  
Andreas Nocker ◽  
Elisa Lindfeld ◽  
Jost Wingender ◽  
Simone Schulte ◽  
Matthias Dumm ◽  
...  
Keyword(s):  
Nutrient Removal ◽  
Nutrient Concentration ◽  
Water Systems ◽  
Transient Effect ◽  
Time Intervals ◽  
Water Microbiology ◽  
Live Bacteria ◽  
Cleaning Procedures ◽  
Autochthonous Bacteria ◽  
Chemical Disinfection

Abstract Thermal and chemical disinfection of technical water systems not only aim at minimizing the level of undesired microorganisms, but also at preventing excessive biofouling, clogging and interference with diverse technical processes. Typically, treatment has to be repeated in certain time intervals, as the duration of the effect is limited. The transient effect of disinfection was demonstrated in this study applying different treatments to water and biofilms including heat, chlorination, a combination of hydrogen peroxide and peracetic acid and monochloramine. Despite the diverse treatments, the reduction in live bacteria was followed by regrowth in all cases, underlining the universal validity of this phenomenon. The study shows that autochthonous bacteria could reach the concentrations given prior to treatment. The reason is seen in the nutrient concentration that has not changed and that forms the basis for regrowth. Nutrients are released by disinfection from lysed cells or are still fixed in dead biomass that is subsequently scavenged by necrotrophic growth. Treatment cycles therefore only provide a transient reduction of water microbiology if nutrients are not removed. When aiming at greater sustainability of the effect, biocidal treatment has to be equally concerned about nutrient removal by subsequent cleaning procedures as about killing efficiency.

scholarly journals The accuracy of gypsum casts obtained from the disinfected extended-pour alginate impressions through prolonged storage times

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Rania A. Sharif ◽  
Khalid M. Abdelaziz ◽  
Najla M. Alshahrani ◽  
Fatimah S. Almutairi ◽  
Mohrah A. Alaseri ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Storage Time ◽  
Prolonged Storage ◽  
Time Intervals ◽  
Superior Surface ◽  
Stability Data ◽  
Surface Detail ◽  
Storage Times ◽  
One Way Anova ◽  
Chemical Disinfection

Abstract Background Manufacturers of the extended-pour alginates claimed their dimensional stability through prolonged storage. No data confirmed the ability of these materials to maintain their dimensions and the reproduced oral details following their chemical disinfection. Therefore, this study evaluated the dimensional stability and surface detail reproduction of gypsum casts obtained from disinfected extended-pour alginate impressions through different storage time intervals. Methods Two hundred and forty three hydrocolloid impressions were made from one conventional (Tropicalgin) and two extended-pour (Hydrogum 5 and Chromaprint premium) alginates. These impressions were subjected to none, spray and immersion disinfection before their storage in 100% humidity for 0, 72 and 120 h. The dimensional stability and the surface detail reproduction were indirectly evaluated under low angle illumination on the resulted gypsum casts. At α = 0.05, the parametric dimensional stability data were analyzed using One-Way ANOVA and Tukey’s comparisons, while the nonparametric detail reproduction data were analyzed using KrusKal Wallis and Mann–Whitney's tests. Results All gypsum casts exhibited a degree of expansion; however, the recorded expansion values did not differ between test categories (P > 0.05). Generally, casts obtained from spray-disinfected impressions showed lower detail accuracy (P < 0.05). Immersion-disinfected extended-pour alginates produced casts with better detail accuracy following 120 h of storage (P < 0.05). Conclusion All alginates materials offer comparable cast dimensions under different testing circumstances. Extended-pour alginates offer casts with superior surface details following their immersion disinfection and 120 h of storage. Spray-disinfection using 5.25% sodium hypochlorite affects the surface details of casts obtained from conventional and extended-pour alginates adversely.

Chemical disinfection of Legionella in hot water systems biofilm: a pilot-scale 1 study

2011 ◽  
Vol 64 (3) ◽  
pp. 708-714 ◽  
Author(s):  
Maha Farhat ◽  
Marie-Cécile Trouilhé ◽  
Christophe Forêt ◽  
Wolfgang Hater ◽  
Marina Moletta-Denat ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Contact Time ◽  
Pilot Scale ◽  
Water Systems ◽  
Hot Water ◽  
The Other ◽  
Cooling Towers ◽  
Test Loop ◽  
Growing Conditions ◽  
Chemical Disinfection

Legionella bacteria encounter optimum growing conditions in hot water systems and cooling towers. A pilot-scale 1 unit was built in order to study the biofilm disinfection. It consisted of two identical loops, one used as a control and the other as a ‘Test Loop’. A combination of a bio-detergent and a biocide (hydrogen peroxide + peracetic acid) was applied in the Test Loop three times under the same conditions at 100 and 1,000 mg/L with a contact time of 24 and 3–6 hours, respectively. Each treatment test was preceded by a three week period of biofilm re-colonization. Initial concentrations of culturable Legionella into biofilm were close to 103 CFU/cm2. Results showed that culturable Legionella spp. in biofilm were no longer detectable three days following each treatment. Nevertheless, initial Legionella spp. concentrations were recovered 7 days after the treatments (in two cases). Before the tests, Legionella spp. and L. pneumophila PCR counts were both about 104 GU/cm2 in biofilm and they both decreased by 1 to 2 log units 72 hours after each treatment. The three tests had a good but transient efficiency on Legionella disinfection in biofilm.

scholarly journals Nutrient removal by apple, pear and cherry nursery trees

2016 ◽  
Vol 11 ◽  
Author(s):  
Giovambattista Sorrenti ◽  
Maurizio Quartieri ◽  
Silvia Salvi ◽  
Moreno Toselli
Keyword(s):  
Nutrient Removal ◽  
Nutrient Concentration ◽  
Tree Biomass ◽  
Pome Fruit ◽  
Environmental Implications ◽  
Fruit Species ◽  
Dry Biomass ◽  
Order Of Magnitude ◽  
Nursery Trees ◽  
Root Collar

Given that nursery is a peculiar environment, the amount of nutrients removed by nursery trees represents a fundamental acquisition to optimize fertilization strategies, with economic and environmental implications. In this context, we determined nutrient removal by apple, pear and cherry nursery trees at the end of the nursery growing cycle. We randomly removed 5 leafless apple (Golden Delicious/EMLA M9; density of 30,000 trees ha<sup>-1</sup>), pear (Santa Maria/Adams; density of 30,000 trees ha<sup>-1</sup>) and cherry (Alex<sup>TM</sup>/Gisela®; density of 40,000 trees ha<sup>-1</sup>) trees from a commercial nursery. Trees were divided into roots (below the root collar), rootstock (aboveground between root collar and grafting point) and variety (1-year-old above the grafting point). For each organ we determined biomass, macro (N, P, K, Ca, Mg, S,) and micro (Fe, Mn, Zn, Cu, and B) nutrient concentration. Pear trees were the most developed (650 g tree<sup>-1</sup>, equal to 1.75 and 2.78 folds than apple and cherry trees, respectively) whereas, independently of the species, variety mostly contributed (&gt;50%) to the total tree biomass, followed by roots and then aboveground rootstock. However, the dry biomass and nutrient amount measured in rootstocks (including roots) represent the cumulative amount of 2 and 3seasons, for Gisela® 6 (tissue culture) and pome fruit species (generated by mound layering), respectively. Macro and micronutrients were mostly concentrated in roots, followed by variety and rootstock, irrespective of the species. Independently of the tissue, macronutrients concentration hierarchy was N&gt;Ca&gt;K&gt; P&gt;Mg&gt;S. Removed N by whole tree accounted for 6.58, 3.53 and 2.49 g tree<sup>-1</sup> for pear, apple and cherry, respectively, correspondingto almost 200, 107 and 100 kg N ha<sup>-1</sup>, respectively. High amounts of K and Ca were used by pear (130-140 kg ha<sup>-1</sup>) and apple trees (~50 and 130 kg ha<sup>-1</sup> of K and Ca, respectively), while ~25 kg K ha<sup>-1</sup> and 55 kg Ca ha<sup>-1</sup> were calculated for cherry nursery trees. Among micronutrients, Fe was the most required (~3 kg ha<sup>-1</sup>) independently of the species. B removal ranged between 1.2 and 2.4 kg ha-1 (80, 40 and 30 mg tree<sup>-1</sup> for pear, apple and cherry, respectively) whereas Mn, Cu and Zn accounted for few hundred g ha<sup>-1</sup>, irrespective of the species. Given that nutrient concentration among tissues resulted within the same order of magnitude, irrespective of the species, differences in removal were mainly driven by the tree biomass as proved by the significant correlations between plant dry biomass with most of the nutrients we observed.

Comparison of Biomass and Oil Productivity of Selected Microalgae in Livestock Wastewater

2011 ◽  
Vol 393-395 ◽  
pp. 655-658
Author(s):  
Ying Shen ◽  
Wen Qiao Yuan
Keyword(s):  
Lipid Content ◽  
Nutrient Removal ◽  
Nutrient Concentration ◽  
Basal Medium ◽  
Biofuel Production ◽  
Animal Waste ◽  
Livestock Wastewater ◽  
Lipid Yield ◽  
Scenedesmus Dimorphus ◽  
Oil Productivity

This study aimed to compare the biomass and oil productivity from three selected microalgae strains (Botryocococcus braunii, Scenedesmus dimorphus, and Nannochlorpsis sp) using livestock wastewater for dual purposes of biofuel production and animal waste nutrient removal. The selected algal strains were batch-wise cultivated in the laboratory in Basal medium and livestock wastewater with optimal nutrient concentration. The results indicated that all three algae strains grew better in 50% autoclaved wastewater than in Basal medium. The maximum lipid yield of B. braunii, S. dimorphus, and N. sp were 0.61 g/l (38.88% lipid content), 0.69 g/l (61.76% lipid content), and 1.32 g/l (37.47% lipid content) all in 50% autoclaved wastewater. N and P in wastewater were completely removed by the three selected strains at day 21, respectively.

Drinking water microbiology in a water-efficient building: stagnation, seasonality, and physicochemical effects on opportunistic pathogen and total bacteria proliferation

2020 ◽  
Vol 6 (10) ◽  
pp. 2902-2913 ◽  
Author(s):  
Christian J. Ley ◽  
Caitlin R. Proctor ◽  
Gulshan Singh ◽  
Kyungyeon Ra ◽  
Yoorae Noh ◽  
...  
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Water Conservation ◽  
Potable Water ◽  
Opportunistic Pathogen ◽  
Water Systems ◽  
Water Age ◽  
Water Microbiology ◽  
Degraded Water Quality ◽  
Total Bacteria

The rising trend in water conservation has led to the use of water-efficient fixtures for residential potable water systems, which raises concerns about increasing water age and degraded water quality at the tap.

Side stream biofiltration for improved biofouling control in cooling water systems

2000 ◽  
Vol 41 (4-5) ◽  
pp. 445-451 ◽  
Author(s):  
E.J. Daamen ◽  
J.W. Wouters ◽  
J.T.G. Savelkoul
Keyword(s):  
Nutrient Removal ◽  
Plug Flow ◽  
Water System ◽  
Cooling Water ◽  
Water Systems ◽  
Biofilm Growth ◽  
First Order ◽  
Side Stream ◽  
Cooling Water System ◽  
Kinetic Coefficients

Biological activity in open recirculating cooling water systems may lead to Microbial Induced Corrosion (MIC) and lower heat exchange efficiencies. The use of oxidizing biocides as a tool to control excessive biofilm formation in a cooling water system can be characterised as fighting the symptoms, because it does not take away the main cause of biofilm growth: the availability of nutrients. Due to frequent use of oxidizing biocides the microbial growth rate in the cooling water system studied (1–2 d−1) was even higher than the dilution rate (0.33 d−1). By means of an ASTRASAND®continuous sand filter used as a side stream biofilter it is possible to achieve considerable reductions in nutrients and in suspended biomass contents. The content of nutrients in the filter influent and effluent was expressed in terms of growth rates and was determined by batch experiments. Based on the assumptions of plug flow characteristics and first order reaction kinetics, the kinetic coefficients for nutrient removal were determined at k1=6 h−1 for fine (0.8–1.25 mm) and at k1=4.5 h−1 for coarse (1.4–2.0 mm) filter material. Due to the first order kinetics of nutrient removal and due to the improved filtration efficiencies at increasing influent biomass contents, it is concluded that a side stream biofilter introduces a self regulating process element in the cooling water system, leading to a faster recovery of the cooling water quality after upset conditions. Considerable savings in the use of oxidizing agents can be established.

scholarly journals Nutrient Removal from Chinese Coastal Waters by Large-Scale Seaweed Aquaculture Using Artificial Upwelling

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1754 ◽  
Author(s):  
Fan ◽  
Zhao ◽  
Yao ◽  
Xiao ◽  
Pan ◽  
...  
Keyword(s):  
Nutrient Removal ◽  
Nutrient Concentration ◽  
Large Scale ◽  
Model Simulation ◽  
Jiaozhou Bay ◽  
Ecological Engineering ◽  
Promoting Effect ◽  
Concentration Data ◽  
Ecological Benefit ◽  
Aquaculture Area

Ecological engineering by artificial upwelling for enhancing seaweed growth and consequently increasing nutrient removal from seawater has proved promising in combating intense coastal eutrophication. However, a key issue needs to be answered: how much economic and ecological benefit could this engineering bring if it were to be implemented in national aquaculture areas. This study estimated the promoting effect of nutrient concentration change induced by artificial upwelling on kelp growth using a model simulation based on the temperature, light intensity, and nutrient concentration data from three bays in Shandong Province, China— Aoshan Bay, Jiaozhou Bay, and Sanggou Bay. Our results indicate that ecological engineering by artificial upwelling can increase the average yield of kelp by 55 g per plant. Furthermore, based on the current existing kelp aquaculture area of China and the aquaculture density of 12 plants/m2, we inferred that this ecological engineering could increase the natural kelp yield by 291,956 t and the removal of nitrogen (N) and phosphorus (P) nutrients by 4875–6422 t and 730–1080 t, respectively.

Rotational Characteristics of the Green Solar Corona: 1947-1991

1994 ◽  
Vol 144 ◽  
pp. 139-141 ◽  
Author(s):  
J. Rybák ◽  
V. Rušin ◽  
M. Rybanský
Keyword(s):  
Solar Corona ◽  
World Wide ◽  
Rotation Period ◽  
Original Data ◽  
Coronal Emission ◽  
Time Intervals ◽  
Data Set ◽  
The World ◽  
Coronal Emission Line ◽  
Homogeneous Data

AbstractFe XIV 530.3 nm coronal emission line observations have been used for the estimation of the green solar corona rotation. A homogeneous data set, created from measurements of the world-wide coronagraphic network, has been examined with a help of correlation analysis to reveal the averaged synodic rotation period as a function of latitude and time over the epoch from 1947 to 1991.The values of the synodic rotation period obtained for this epoch for the whole range of latitudes and a latitude band ±30° are 27.52±0.12 days and 26.95±0.21 days, resp. A differential rotation of green solar corona, with local period maxima around ±60° and minimum of the rotation period at the equator, was confirmed. No clear cyclic variation of the rotation has been found for examinated epoch but some monotonic trends for some time intervals are presented.A detailed investigation of the original data and their correlation functions has shown that an existence of sufficiently reliable tracers is not evident for the whole set of examinated data. This should be taken into account in future more precise estimations of the green corona rotation period.

Prolonged Fixation Studies For Spaceflight

1973 ◽  
Vol 31 ◽  
pp. 332-333
Author(s):  
Robert Corbett ◽  
Delbert E. Philpott ◽  
Sam Black
Keyword(s):  
High Pressure ◽  
Living Systems ◽  
Prolonged Storage ◽  
Time Intervals ◽  
Early Signs ◽  
Large Numbers

Observation of subtle or early signs of change in spaceflight induced alterations on living systems require precise methods of sampling. In-flight analysis would be preferable but constraints of time, equipment, personnel and cost dictate the necessity for prolonged storage before retrieval. Because of this, various tissues have been stored in fixatives and combinations of fixatives and observed at various time intervals. High pressure and the effect of buffer alone have also been tried.Of the various tissues embedded, muscle, cartilage and liver, liver has been the most extensively studied because it contains large numbers of organelles common to all tissues (Fig. 1).

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