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This paper reported the studies on the water purification of breeding Hirudo nippanica with photosynthesis bacteria (PBS). The results showed the PBS could reduce effectively the chemical dissolved oxygen, NH(4+)-N, vulcanization and organic matter of water bottom, as well as improve the dissolved oxygen.
Some aspects of the bacteriology of aerobic and anaerobic waste water purification are discussed in view of current opinions and recent developments in the technology of waste water treatment. Various contributions of scientific workers attached to the Department of Microbiology of the Agricultural University, Wageningen, during the past 65 years are summarized. Besides, present investigations are described and research activities in future indicated.
Some 80% of accidental pollution in river water is caused by oil spills. Oil spills can cause serious damage such as suspension of water intake at water purification plants and major harm to ecosystems in the lower reaches of rivers. This is because oil-on-water tends to spread easily, quickly exacerbating the damage. To address this problem, an automated, continuous sensor system with high sensitivity can be used for early detection of spill accidents. We have developed a sensor system for detecting oil-on-water based on a polarization analysis method. Its advantages include: a) no direct contact with sample water; b) minimal maintenance; c) largely unaffected by foreign matter and waves on the water surface; and d) much higher sensitivity than simple visual observation. This paper describes the measurement principle and configuration of the sensor system, and discusses the results of sensitivity tests and tests on the influence of water turbidity, foreign matter and waves. We will also consider some of the limitations of the new system.
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This study was conducted to determine the efflux of specific ions, including fluoride, from a deionization (DI) water purification system (WPS) when the WPS was operated beyond exhaustion of the DI resin. Effluent from the DI WPS was monitored for resistivity, total dissolved solids, pH, and concentrations of silica, fluoride, potassium, and sodium. After 16,000 L of water was purified, the resistivity declined to 0.492 omega Ohm-cm, and silica was released from the DI WPS. Fluoride ions were released after an additional 8,000 L water was treated, and the resistivity fell to 0.07 omega Ohm-cm. The fluoride efflux reached a peak of 32 mg/L, 28 times greater than the original fluoride concentration in the city water. Sodium and potassium ions were released after approximately 26,000 and 32,000 L of water had been treated and reached peaks of 76 and 47 mg/L, respectively. This study confirms that the minimum resistivity standard of 1 omega Ohm-cm for DI water used for hemodialysis should provide an adequate safety margin. Once resistivity fell to 1 omega Ohm-cm, more than 8,000 L of water was treated before fluoride efflux occurred. Accordingly, hemodialysis centers should be attentive to the calculated capacity of their DI WPS and reliably monitor the resistivity to prevent patient illness related to exhaustion of DI resins.
In communities that do not fluoridate water supplies, or homes that have fluoride removed from their water, fluoride supplementation may be necessary. The AAPD guide is reviewed, with dosage recommendations provided. Water purifications are described and reviewed. Dentists should ask their patients about their drinking water.
Presented in this paper are the results of a series of column experiments and a pilot scale test conducted to develop the treatment system of freshwater and wastewater by their percolation through soil and the other materials at the rate of a few metres per day. Materials that had high ability to sorb fulvic acid (FA hereafter) and phosphate ion were selected based on the results of the batch sorption tests and were processed into beads before subjecting them to the column test. The results of the column experiment suggested that the reagents added to increase the strength of the beads reduced the sorption of FA, thus causing the early breakthrough of the FA injected into the column. Less effect from the bead processing was observed for the removal of phosphate ion. Pilot scale test showed that the removal of particulate fraction of phosphorus differed among the materials used. The bead processing technique that can ensure the high water permeability while maintaining the sorption capacity of the material was required for further development of the treatment system.
Removal of anionic pollutants (imazaquin, sulfentrazone, sulfosulfuron) and neutral pollutants (alachlor, acetochlor, chlorotoluron, bromacil) from water by micelles preadsorbed on montmorillonite was studied. Micelles of octadecyltrimethylammonium and benzyldimethylhexadecylammonium (BDMHDA) were used. The micelle-clay systems (1% w/w) removed 87-99% of the pollutants from their water solutions containing 1-33 mg/L of herbicide. The nature of the headgroup of the organic cation, which forms the micelles, is critical. Desorption of imazaquin and acetochlor from 0.3% (w/w) suspension of BDMHDA-clay complex after 24 h was around 7% in the range of adsorbed amounts from 0.6 to 15.3 mg/g. These results indicate rather slow rates and small extents of release of pollutants from micelle-clay complexes. Column filters (25 cm) made of a mixture of quartz sand and BDMHDA micelle-clay complex at 100:1 w/w ratio removed at least 99% of above pollutants from initial solutions containing 10 mg/L; 99.5 and 97% of sulfosulfuron and alachlor were removed from their initial solutions containing 200 and 5 microg/L, respectively. These data indicate that micelle-clay complexes are very efficient for water purification from organic contaminants.
A new method for potable water treatment was brought forward and studied in this research. The treatment process was named as counterflow co-flocculation flotation (CC-FF). Pilot experiment was conducted and the operational parameters were presented. The optimized operational conditions are as follows: the detention time is 6-11 min with hydraulic load of 9-16 m3/(m2 h); the recycle ratio should be no less than 8% while the distance between the inlet of source water and recycle water should be greater than 1200 mm. If the source water turbidity was lower than 100 NTU, 0.12-0.35 mmol/L Al dosage is enough to maintain efficient turbidity removal. Since the flocculation and flotation processes were carried out in the same tank, this new technique has some advantages than the conventional flocculation-flotation methods. Firstly, the microbubbles released from recycle water will participate in the flocculation of suspended particles, hence the low-density but high shear-force-resistance flocci could be formed. Secondly, the microflocci or suspended particles will be functioned as 'nucleus' during the bubble formation from air-dissolved recycle water. Thirdly, in the midsection of the tank a blanket of bubble-microfloc aggregates could be formed, which will intercept the downward-flow flocci and upward-flow bubbles efficiently, thus keep the renovation and stability of the blanket.
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Two young adults presented with thyrotoxicosis after increased iodide ingestion in the course of backpacking trips to Central and South America, during which each of them used an iodinated preparation for water purification. In both cases, serologic tests were positive for antithyroid peroxidase antibodies, and one had a family history of immune thyroid disease. We suggest that in these two cases the condition was a variant of iodide-induced thyrotoxicosis, reflecting an inadequate response to iodide excess in association with a presumed preexisting asymptomatic immune thyroid disease. This observation adds a new consideration for travelers' consultation.
A coagulation-microfiltration combination process was used in treatment of simulative surface water. The effects of operational conditions such as filtration time, ceasing time and aeration intensity on the membrane permeability and organic removals were investigated. Experiment results showed that the membrane permeability could be improved through changing the operational conditions. Decreasing the filtration time or increasing the ratio of filtration time/ceasing time was favorable to enhance the membrane permeability. As the aeration intensity increased, the membrane permeability was also enlarged to some extent, but was not improved obviously anymore when the aeration intensity was over the critical value of around 4m3h(-1). Different wash methods to remove membrane fouling were attempted. The results suggested that coagulation in the process mainly led to change of the deposit cake-caused membrane fouling, which could be physically removed by surface wash. Organic removals, in terms of OC and UV254, apparently varied with the operational conditions. An inverse relationship between organic removals and membrane permeability was found. Lower membrane permeability led to higher OC and UV254 removals.
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Five methods of water purification for culture media preparation have been described. The quality of media thus prepared has been assessed retrospectively by relating to the fertilization and pregnancy rates of a total of 646 treatment cycles in an in-vitro fertilization and embryo transfer (IVF-ET) programme. All media for human use was subjected to quality control assessment in a mouse embryo culture system. Although no differences were seen in the fertilization rates or the proportion of women proceeding to embryo transfer, significant differences were seen in the pregnancy rates. The highest pregnancy rates were obtained using rainwater distilled six times (22/100, 22%) or eight times (40/184, 21.7%), and water polished using a Milli-Q water purifying system (41/181, 22.7%). Significantly lower pregnancy rates were obtained when the water was purified using an alternative Milli-Q system (9/89, 10.1%) or dam water distilled six times (6/63, 9.5%). These findings may reflect contamination of local dam water supplies but demonstrate the difficulty in purifying water for the preparation of culture medium.
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Polyelectrolytes used in the practice of water supply to the population were comparatively hygienically studied, by using a complex of hazard indices and a new approach to sanitary-and-epidemiological evaluation of the safety of water-soluble polymers is substantiated. The anionic and cationic flocculating agents from different chemical classes, such as Superflok A-100, Fennopol A 321E, Fennopol K 221E, Praestol 2530 TR, VPK-402, Superflok C-577, Saipan, KF-91, Ecosol-401, a low molecular-weight sodium polyacrylate were tested as model compounds. Moreover, the information already available in the scientific literature on the toxicity of synthetic polyelectrolytes was analyzed. The generalized maximum permissible concentrations were substantiated for individual chemical classes of synthetic polyelectrolytes: polyacrylamides, polyamines, polydiallyldimethylammonium chloride.
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