Cooling Tower Water Research Articles

Detection of Legionella species in environmental water by the quantitative PCR method in combination with ethidium monoazide treatment.

We detected Legionella species in 111 bath water samples and 95 cooling tower water samples by using a combination of conventional plate culture, quantitative polymerase chain reaction (qPCR) and qPCR combined with ethidium monoazide treatment (EMA-qPCR) methods. In the case of bath water samples, Legionella spp. were detected in 30 samples by plate culture, in 85 samples by qPCR, and in 49 samples by EMA-qPCR. Of 81 samples determined to be Legionella-negative by plate culture, 56 and 23 samples were positive by qPCR and EMA-qPCR, respectively. Therefore, EMA treatment decreased the number of Legionella-positive bath water samples detected by qPCR. In contrast, EMA treatment had no effect on cooling tower water samples. We therefore expect that EMA-qPCR is a useful method for the rapid detection of viable Legionella spp. from bath water samples.

Mixed heterolobosean and novel gregarine lineage genes from culture ATCC 50646: Long-branch artefacts, not lateral gene transfer, distort α-tubulin phylogeny

Contradictory and confusing results can arise if sequenced ‘monoprotist’ samples really contain DNA of very different species. Eukaryote-wide phylogenetic analyses using five genes from the amoeboflagellate culture ATCC 50646 previously implied it was an undescribed percolozoan related to percolatean flagellates (Stephanopogon, Percolomonas). Contrastingly, three phylogenetic analyses of 18S rRNA alone, did not place it within Percolozoa, but as an isolated deep-branching excavate. I resolve that contradiction by sequence phylogenies for all five genes individually, using up to 652 taxa. Its 18S rRNA sequence (GQ377652) is near-identical to one from stained-glass windows, somewhat more distant from one from cooling-tower water, all three related to terrestrial actinocephalid gregarines Hoplorhynchus and Pyxinia. All four protein-gene sequences (Hsp90; α-tubulin; β-tubulin; actin) are from an amoeboflagellate heterolobosean percolozoan, not especially deeply branching. Contrary to previous conclusions from trees combining protein and rRNA sequences or rDNA trees including Eozoa only, this culture does not represent a major novel deep-branching eukaryote lineage distinct from Heterolobosea, and thus lacks special significance for deep eukaryote phylogeny, though the rDNA sequence is important for gregarine phylogeny. α-tubulin trees for over 250 eukaryotes refute earlier suggestions of lateral gene transfer within eukaryotes, being largely congruent with morphology and other gene trees.

Genome Sequence of Legionella massiliensis, Isolated from a Cooling Tower Water Sample

We present the draft genome sequence of Legionella massiliensis strain LegAT, recovered from a cooling tower water sample, using an amoebal coculture procedure. The strain described here is composed of 4,387,007 bp, with a G+C content of 41.19%, and its genome has 3,767 protein-coding genes and 60 predicted RNA genes.

Microbial and Physiochemical Quality of Effluent Water from a Brewery in Benin City, Midwestern Nigeria

Aims: The present study w as set up to investigate the physicochemical and microbial contents of waste water discharged into the Ikpoba Rivers as well as water samples obtained from the river at different points of collection with a view to determining impact on the water body. Study Design: The design chosen for the study was complete randomization, considering the homogeneity of the experimental plots from which samples were collected. Place and Duration of Study: Samples were collected during the late rainy season of August 2012 from both the Ikpoba River, Benin City, Nigeria and from effluent treatment plants in a brewery in Benin City. Methodology: Samples were collected in three different locations; in the brewery, from the brewery effluent samples point, as well as in the Ikpoba River, where brewery effluent Original Research Article Ikhajiagbe et al; JSRR, Article no. JSRR.2014.XXX 515 samples mixes with the river water. Non-effluent samples were also collected from the brewery, these included glycol, condensate, boiler feed, brew cold and cooling tower water (CTW). Samples of the brewery effluent discharged into the river were also collected from the brewery effluent samples channel. On the Ikpoba River, five different sampling point were identified; contact point (CP) of the discharged brewery effluent samples with the river water, 5m and 10m before contact point, as well as 5m and 10m after contact point, respectively. Results: The pH of glycol was 7.8, compared to those of the condensate and boiler feed which were both 5.8 and 5.5 respectively. The pH of the brewery effluent samples was 5.8, however at the point of contact of brewery effluent samples with Ikpoba River, pH dropped to 4.8. The surface water temperature ranges of non-effluent samples materials was 29.6 – 29.9oC, as compared to 29.2oC which was the temperature of the brewery effluent samples before contact with Ikpoba River. The heavy metals detected in the noneffluent samples and brewery effluent samples samples were iron, magnesium, copper and zinc. Lead was only detected in the non-effluent samples while nickel and vanadium were not detected in both samples. Conclusion: Results showed that the effluents samples from the industry altered the physical, chemical and biological nature of the receiving water body. However, comparison with WHO and FMENV standards showed no deviation from required benchmarks, and as such the samples were adjudged ecologically safe.

Firmicutes dominate the bacterial taxa within sugar-cane processing plants

Sugar cane processing sites are characterised by high sugar/hemicellulose levels, available moisture and warm conditions, and are relatively unexplored unique microbial environments. The PhyloChip microarray was used to investigate bacterial diversity and community composition in three Australian sugar cane processing plants. These ecosystems were highly complex and dominated by four main Phyla, Firmicutes (the most dominant), followed by Proteobacteria, Bacteroidetes, and Chloroflexi. Significant variation (p < 0.05) in community structure occurred between samples collected from ‘floor dump sediment’, ‘cooling tower water’, and ‘bagasse leachate’. Many bacterial Classes contributed to these differences, however most were of low numerical abundance. Separation in community composition was also linked to Classes of Firmicutes, particularly Bacillales, Lactobacillales and Clostridiales, whose dominance is likely to be linked to their physiology as ‘lactic acid bacteria’, capable of fermenting the sugars present. This process may help displace other bacterial taxa, providing a competitive advantage for Firmicutes bacteria.

Design improvement of central cooling plant for energy saving using cooling tower water

This paper investigates and recommends design improvement for a central cooling plant to enhance the energy efficiency of the system. A storage tank together with an immersed heat exchanger is installed in the liquid line between the condenser and expansion valve to utilize the make-up water of the cooling tower. The heat exchanger uses the make-up water to reduce the refrigerant temperature leaving the condenser and thus enhance the refrigerant sub-cooling. For this purpose, an existing central cooling plant of a commercial building, located in a hot and dry climate region, is used for experimentation and data collection. The energy consumption and relevant data of the existing central cooling plant were acquired over the course of a typical week in summer. First, theoretical-empirical system models including mechanistic relations between components are developed. A numerical algorithm together with monitored data and mathematical model implemented on a transient system simulation tool is used to predict the performance of the new design under transient loads. The integrated simulation tool was validated by comparing predicted and measured power consumption of the central cooling plant. Comparison of the proposed system with existing cooling plant is included in this paper to demonstrate the advantages of our new configuration. Results show that about 9.7% in average and up to 14% power saving can be obtained by using our design while maintaining the comfort condition inside the building.

Mycobacteria in Finnish cooling tower waters

Evaporative cooling towers are water systems used in, e.g., industry and telecommunication to remove excess heat by evaporation of water. Temperatures of cooling waters are usually optimal for mesophilic microbial growth and cooling towers may liberate massive amounts of bacterial aerosols. Outbreaks of legionellosis associated with cooling towers have been known since the 1980's, but occurrences of other potentially pathogenic bacteria in cooling waters are mostly unknown. We examined the occurrence of mycobacteria, which are common bacteria in different water systems and may cause pulmonary and other soft tissue infections, in cooling waters containing different numbers of legionellae. Mycobacteria were isolated from all twelve cooling systems and from 92% of the 24 samples studied. Their numbers in the positive samples varied from 10 to 7.3 × 10(4) cfu/L. The isolated species included M. chelonae/abscessus, M. fortuitum, M. mucogenicum, M. peregrinum, M. intracellulare, M. lentiflavum, M. avium/nebraskense/scrofulaceum and many non-pathogenic species. The numbers of mycobacteria correlated negatively with the numbers of legionellae and the concentration of copper. The results show that cooling towers are suitable environments for potentially pathogenic mycobacteria. Further transmission of mycobacteria from the towers to the environment needs examination.

INFLUENCE OF ENVIRONMENTAL CONTAMINATION ON CHROMIUM AND ZINC CONTENT OF SELECTED EDIBLE VEGETABLES SAFETY AND NUTRITIONAL ASPECT

The content of heavy metals in vegetables may be increased by contamination through varioussources. It is therefore important to test and maintain the quality of vegetables in terms of heavymetals, in view of recent recommendations to increase their intake. People who are notexcessively exposed in their occupation to environmental trace element contamination comesinto contact with these pollutants through the contaminated foods and water they ingest.Vegetables are the first link in the trophic chain affected by this contamination.Chromium and Zinc are essential dements required for normal functions in plants and animals.Chromium has a complicated environmental chemistry and plays a role as both a nutrient and atoxic agent, also as a known carcinogen. Chromium enters the environment as a result of effluentdischarge from steel work, electroplating, tanning industry, oxidative dyeing, chemicalindustries, and cooling water towers. Zinc is biologically one of the most important metal and isapparently necessary to all forms of life. Although it is not very toxic to animals zinc isphytotoxic and soil can be "poisoned" by exposure to zinc smelting or from application of zinc -rich sewage sludge. Zinc oxide is used as an accelerating and activating agent for hardeningrubber product. Tires and tire wear is a major vector for the transfer of Zn to the environment.In this study the Cr &amp; Zn content cf edible vegetables commonly grown and sold in Colombo,Kandy &amp; Balangoda were determined by flame atomic absorption spectrometer(FAAS) after dryashing. For the dry ashing procedure, dried samples were used and ashed at 450 OC overnight.Ashed samples were dissolved in 0.1 M HN03. Extensive validation of the proposed methodwas carried out by the standard addition methodIn the FAAS used measurement could be made over a linear range between 0.119-5 ug/ml for Crand 0.0374-1.64 ug/ml Zn respectively. Cr and Zn of Colombo samples varied from 0.0079-0.2044 mg/kg and 1.13-3.59 mg/Kg respectively. Both Cr and Zn levels in Balangoda samplesvaried from 0.006-0.0468 rug/Kg :respectively. Kandy samples also gave similar values asBalangoda samples.It is seen that the leafy vegetable samples obtained from Colombo had a higher mean level of Crand Zn when compared to those obtained from Kandy and Balangoda: Tubers and roots gavelower mean level of Cr and Zn than leafy vegetables. Therefore it confirms the role ofenvironmental influence to the content of these elements, which could be attributed to thecontaminated soil, dust, sewage or water sources. Results obtained in this study seem to suggestthat environmental contamination plays a role in the Cr content of edible vegetables.

Studies to control biofilm formation by coupling ultrasonication of natural waters and anodization of titanium

The main objective of this study was to investigate the combined effect of ultrasonication of natural waters and anodization of titanium on microbial density and biofilm formation tendency on titanium surfaces. Application of 24kHz, 400W high power ultrasound through a 14mm horn type SS (stainless steel) Sonicator with medium amplitude of 60% for 30min brought about three order decrease in total bacterial density of laboratory tap water, cooling tower water and reservoir water and two order decrease in seawater. Studies on the effect of ultrasonication on dilute pure cultures of Gram-negative and Gram-positive bacteria showed five order and three order decrease for Pseudomonas sp. and Flavobacterium sp. respectively and two order and less than one order decrease for Bacillus sp. and Micrococcus sp. respectively. Ultrasonication increased lag phase and reduced logarithmic population increase and specific growth rate of Gram-negative bacteria whereas for Gram-positive bacteria specific growth rate increased. Studies on the biofilm formation tendency of these ultrasonicated mediums on titanium surface showed one order reduction under all conditions. Detailed biofilm imaging by advanced microscopic techniques like AFM, SEM and epifluorescence microscopy clearly visualized the lysed/damaged cells and membrane perforations due to ultrasonication. Combination of ultrasonication and anodization brought about maximum decrease in bacterial density and biofilm formation with greater than two order decrease in seawater, two order decrease in Bacillus sp. culture and more than four order decrease in Flavobacterium sp. culture establishing the synergistic effect of anodization and ultrasonication in this study.

Fast immunosensing technique to detect Legionella pneumophila in different natural and anthropogenic environments: comparative and collaborative trials

BackgroundLegionellosis is an uncommon form of pneumonia. After a clinical encounter, the necessary antibiotic treatment is available if the diagnosis is made early in the illness. Before the clinical encounter, early detection of the main pathogen involved, Legionella pneumophila, in hazardous environments is important in preventing infectious levels of this bacterium. In this study a qualitative test based on combined magnetic immunocapture and enzyme-immunoassay for the fast detection of Legionella pneumophila in water samples was compared with the standard method, in both comparative and collaborative trials. The test was based on the use of anti-Legionella pneumophila antibodies immobilized on magnetic microspheres. The final protocol included concentration by filtration, resuspension and immunomagnetic capture. The whole assay took less than 1 hour to complete.ResultsA comparative trial was performed against the standard culture method (ISO 11731) on both artificially and naturally contaminated water samples, for two matrices: chlorinated tap water and cooling tower water. Performance characteristics of the test used as screening with culture confirmation resulted in sensitivity, specificity, false positive, false negative, and efficiency of 96.6%, 100%, 0%, 3.4%, and 97.8%, respectively. The detection limit at the level under which the false negative rate increases to 50% (LOD50) was 93 colony forming units (CFU) in the volume examined for both tested matrices. The collaborative trial included twelve laboratories. Water samples spiked with certified reference materials were tested. In this study the coincidence level between the two methods was 95.8%.ConclusionResults demonstrate the applicability of this immunosensing technique to the rapid, simple, and efficient detection of Legionella pneumophila in water samples. This test is not based on microbial growth, so it could be used as a rapid screening technique for the detection of L. pneumophila in waters, maintaining the performance of conventional culture for isolation of the pathogen and related studies.

The corrosion behaviour of galvanized steel in cooling tower water containing a biocide and a corrosion inhibitor

The corrosion behaviour of galvanized steel in cooling tower water containing a biocide and a corrosion inhibitor was investigated over a 10-month period in a hotel. Planktonic and sessile numbers of sulphate reducing bacteria (SRB) and heterotrophic bacteria were monitored. The corrosion rate was determined by the weight loss method. The corrosion products were analyzed by energy dispersive X-ray spectroscopy and X-ray diffraction. A mineralized, heterogeneous biofilm was observed on the coupons. Although a biocide and a corrosion inhibitor were regularly added to the cooling water, the results showed that microorganisms, such as SRB in the mixed species biofilm, caused corrosion of galvanized steel. It was observed that Zn layers on the test coupons were completely depleted after 3 months. The Fe concentrations in the biofilm showed significant correlations with the weight loss and carbohydrate concentration (respectively, p < 0.01 and p < 0.01).

Life Cycle Water Usage in CdTe Photovoltaics

Life cycle water withdrawal for cadmium telluride photovoltaics (CdTe PV) ranges from approximately 382-425 L/MWh, with only ~12% from direct on-site usage. The remainder is related to indirect water withdrawal from the use of grid electricity and raw materials throughout the product life cycle. Approximately half of life cycle water withdrawal is associated with module manufacturing, one-third from balance of systems (BOS), and the remainder from takeback and recycling. Primary contributors to life cycle water withdrawal are the use of grid electricity, glass, and on-site water during manufacturing; steel, copper, inverters, and on-site water in the BOS; and electricity, chemical use, and transport during takeback and recycling. During manufacturing, water consumption is approximately one quarter of withdrawal and is due to cooling tower water evaporation and site irrigation. When deployed in the U.S. Southwest, a CdTe PV array can provide net displacement of life cycle water withdrawal of over 1700-5600 L/MWh relative to grid electricity.

Chromium Geochemistry in a Wetland Environment

Cooling tower water ranging between 7 to 18mg/L of Cr(VI) was released to a stream channel entering a wetland at Los Alamos National Laboratory, New Mexico, USA from 1956 to 1972. The wetland contains between 5700 and 27,000kg total Cr mainly as Cr(III), with a median mass of 11,000kg total Cr, representing 21 to 49% of the total Cr. Chemical analyses conducted on wetland sediments show that 97.3 to 99.9% of the Cr is stable as Cr(III). Mass balance calculations confirm that there are sufficient concentrations of Fe(II) along with the organic-rich sediments to maintain Cr(III) stability within the wetland.

Investigation of N-acyl homoserine lactone (AHL) molecule production in Gram-negative bacteria isolated from cooling tower water and biofilm samples

In this study, 99 Gram-negative rod bacteria were isolated from cooling tower water, and biofilm samples were examined for cell-to-cell signaling systems, N-acyl homoserine lactone (AHL) signal molecule types, and biofilm formation capacity. Four of 39 (10 %) strains isolated from water samples and 14 of 60 (23 %) strains isolated from biofilm samples were found to be producing a variety of AHL signal molecules. It was determined that the AHL signal molecule production ability and the biofilm formation capacity of sessile bacteria is higher than planktonic bacteria, and there was a statistically significant difference between the AHL signal molecule production of these two groups (p < 0.05). In addition, it was found that bacteria belonging to the same species isolated from cooling tower water and biofilm samples produced different types of AHL signal molecules and that there were different types of AHL signal molecules in an AHL extract of bacteria. In the present study, it was observed that different isolates of the same strains did not produce the same AHLs or did not produce AHL molecules, and bacteria known as AHL producers did not produce AHL. These findings suggest that detection of signal molecules in bacteria isolated from cooling towers may contribute to prevention of biofilm formation, elimination of communication among bacteria in water systems, and blockage of quorum-sensing controlled virulence of these bacteria.

Related Giant Viruses in Distant Locations and Different Habitats: Acanthamoeba polyphaga moumouvirus Represents a Third Lineage of the Mimiviridae That Is Close to the Megavirus Lineage

The 1,021,348 base pair genome sequence of the Acanthamoeba polyphaga moumouvirus, a new member of the Mimiviridae family infecting Acanthamoeba polyphaga, is reported. The moumouvirus represents a third lineage beside mimivirus and megavirus. Thereby, it is a new member of the recently proposed Megavirales order. This giant virus was isolated from a cooling tower water in southeastern France but is most closely related to Megavirus chiliensis, which was isolated from ocean water off the coast of Chile. The moumouvirus is predicted to encode 930 proteins, of which 879 have detectable homologs. Among these predicted proteins, for 702 the closest homolog was detected in Megavirus chiliensis, with the median amino acid sequence identity of 62%. The evolutionary affinity of moumouvirus and megavirus was further supported by phylogenetic tree analysis of conserved genes. The moumouvirus and megavirus genomes share near perfect orthologous gene collinearity in the central part of the genome, with the variations concentrated in the terminal regions. In addition, genomic comparisons of the Mimiviridae reveal substantial gene loss in the moumouvirus lineage. The majority of the remaining moumouvirus proteins are most similar to homologs from other Mimiviridae members, and for 27 genes the closest homolog was found in bacteria. Phylogenetic analysis of these genes supported gene acquisition from diverse bacteria after the separation of the moumouvirus and megavirus lineages. Comparative genome analysis of the three lineages of the Mimiviridae revealed significant mobility of Group I self-splicing introns, with the highest intron content observed in the moumouvirus genome.

Thionine‐Bromate as a New Reaction System for Kinetic Spectrophotometric Determination of Hydrazine in Cooling Tower Water Samples

A simple, selective, and inexpensive kinetic method was developed for the determination of hydrazine based on its inhibitory effect on the thionine‐bromate system in sulfuric acid media. The reaction was monitored spectrophotometrically at 601 nm by a fixed time method. The effect of different parameters such as concentration of reactants, ionic strength, temperature, and time on the rate of reaction was investigated, and the optimum conditions were obtained. Under optimum conditions, the calibration curve was linear in the concentration range from 0.8–23.0 μg mL−1 of hydrazine, and the detection limit of the method was 0.22 μg mL−1. The relative standard deviation for five replicate determinations of 1.0 μg mL−1 of hydrazine was 0.74%. The potential of interfering effect of foreign species on the hydrazine determination was studied. The proposed method was successfully applied for the determination of hydrazine in different water samples.

Analysis of population structure among Korean and Japanese Legionella pneumophila isolates using hsp60 sequences

The population structure of Korean (150 strains) and Japanese (92 strains) Legionella pneumophila isolates along with 18 reference strains were investigated using hsp60 sequence (1647 bp) analysis. Twelve clonal subgroups (hsP-I to hsP-X and hsF-I and hsF-II) were designated on the hsp60 tree, inferred from representative sequences using the neighbor-joining method. Some of the isolates showed unique subgroups depending on the source of isolates, including hsP-I, hsF-I, and hsF-II from cooling tower water, and subgroups hsP-VIII and hsP-X from circulating hot water bath. These subgroups may be useful for epidemiological studies to chase or specify sources of infection in Korea and Japan.

Automated dead-end ultrafiltration of large volume water samples to enable detection of low-level targets and reduce sample variability

A Portable Multi-use Automated Concentration System (PMACS) concentrates micro-organisms from large volumes of water through automated dead-end ultrafiltration and backflushing. The ability to detect microbial targets from ground, surface and cooling tower waters collected using standard methods was compared with samples from the PMACS in this study. PMACS (100 l) and standard grab samples (100-500 ml) were collected from sites in Florida and South Carolina, USA. Samples were analysed for the presence of faecal indicator bacteria (FIB; ground and surface water) or Legionella pneumophila (Lp; cooling tower water). FIB were enumerated by growth on selective media following membrane filtration or in IDEXX defined substrate media. Lp cells were detected by direct fluorescence immunoassay using FITC-labelled monoclonal antibodies targeting serogroups 1, 2, 4 and 6. FIB were found in PMACS samples from ground and surface waters when their concentrations were below detection limits in grab samples. The concentrations of Lp in cooling tower samples collected over 5 months were more consistent in PMACS samples than grab samples. These data demonstrate that PMACS concentration is advantageous for water monitoring. FIB were detected in PMACS samples when their concentrations were below the detection limits of the standard methods used. PMACS processing provided more representative samples of cooling tower waters reducing sample variability during long-term monitoring. This study highlights the utility of PMACS processing for enhanced monitoring of water for low-level microbial targets and for reducing sample variability in long-term monitoring programmes.

Method and Implementation of Energy-Saving Control for Industrial Cooling Water Tower Pump

This article introduce a kind of energy-saving control method and implementation for a tower pump in industrial cooling water system (hot tub→ up tower pump→ cooling tower→ cold pool). Under the conditions without changing the original industrial cooling water’s normal operating, the method of temperature control liquid-level under the protection of pressure to regulate and control the energy-saving process of cooling water on tower pump was used. According to the hot tub’s actual temperature and cold pool’s temperature which has process requirements can automatically regulate the hot tub’s liquid height or the height difference between hot tub and cold pool. It can finally automatically control the natural flow rate of the connected overflow hole or connecting pipe, thereby reducing the pump flow rate on tower to ensure the purpose of siginificant energy-saving on the basis of process demand. The comprehensive energy-saving rate can be 40% to 60% or more.

Distribution of Monoclonal Antibody Subgroups and Sequence-Based Types among Legionella pneumophila Serogroup 1 Isolates Derived from Cooling Tower Water, Bathwater, and Soil in Japan

Legionella pneumophila serogroup (SG) 1 is the most frequent cause of legionellosis. This study analyzed environmental isolates of L. pneumophila SG 1 in Japan using monoclonal antibody (MAb) typing and sequence-based typing (SBT). Samples were analyzed from bathwater (BW; n = 50), cooling tower water (CT; n = 50), and soil (SO; n = 35). The distribution of MAb types varied by source, with the most prevalent types being Bellingham (42%), Oxford (72%), and OLDA (51%) in BW, CT, and SO, respectively. The ratios of MAb 3/1 positive isolates were 26, 2, and 14% from BW, CT, and SO, respectively. The environmental isolates from BW, CT, and SO were divided into 34 sequence types (STs; index of discrimination [IOD] = 0.973), 8 STs (IOD = 0.448), and 11 STs (IOD = 0.879), respectively. Genetic variation among CT isolates was smaller than seen in BW and SO. ST1 accounted for 74% of the CT isolates. The only common STs between (i) BW and CT, (ii) BW and SO, and (iii) CT and SO were ST1, ST129, and ST48, respectively, suggesting that each environment constitutes an independent habitat.