Potable water treatment for some asbestiform minerals: optimization and turbidity data

A study has been undertaken to optimize conventional alum coagulation treatment of water for asbestos fibre removal. The results indicate that both the alum and polyelectrolyte concentrations significantly effect the quality of the treated water. Optimum results were obtained with alum concentrations of 30–50 ppm and polyelectrolyte concentrations of 0.3–0.6 ppm. Rapid coagulation/direct filtration has been evaluated and the results found to be comparable to conventional treatment employing flocculation and sedimentation. A survey of turbidities and fibre concentrations for several municipal water supplies indicate that no systematic relationship exists between these two parameters.     

Purification of natural water by ceramic microfiltration membranes from clayey minerals

The paper has investigated separation properties of home-made tube microfiltration ceramic membranes from clayey minerals when purifying underground and surface natural waters by tangential microfiltration. The paper has high efficiency of purifying such waters of suspended matter (up to 99.9%) of iron compounds (up to 99.8%) and manganese (up to 60%).     

Use of some natural and waste materials for waste water treatment

A fundamental study was conducted to assess removal and filtration capacity of waste and natural indigenous materials as treatment mediums e.g., shell, limestone, waste paper mixed with refuse concrete, refuse cement, also processed nitrolite, charcoal-bio and charcoal. Under room temperature condition removal of phosphoric, nitric and ammonium-ions, filtration of suspended substance (SS) together with removal of COD in waste water was investigated. Influence of particle size effect for all treatment mediums except for waste paper was pursued. Significant improvement of waste water quality with respect to SS, phosphoric ions and decrease in COD is possible by treating with these filtration mediums. With specific reference to some treatment mediums NO3-N and NH4-N showed reasonable improvement in quality, although generally removal effect was not very significant. Efficacy of treatment was dependent on the particle size of treatment mediums in general, however, nitrolite for NH4--N, charcoal-A for SS and COD, refuse cement mixed with waste paper for PO4 ion removal showed insignificant variability on the particle size effect. Results of this fundamental study demonstrate effectiveness and feasibility for applied application of these proposed waste and naturally available treatment ingredients at lower cost.     

Evaluation of eighteen west african plants for water purification,potential use for rural water treatment

The current study evaluated the effectiveness of 18 West African plants for water purification. Water samples from 18 sites were collected in six villages in the Guiglo and Mankono regions of Côte d’Ivoire and analyzed for their potability according to WHO standards. Turbid water samples were treated by coagulation flocculation and sedimentation, with 18 plant extracts as coagulants, at concentrations of 200 mg·L^–1. Moringa oleifera and chlorination were used as controls. Of the 18 water samples analyzed, three from hydraulic pumps were safe for drinking. For the 15 remaining samples (100–150 NTU), turbidity was reduced by 92% using Panda oleosa, Euadenia trifoliolata, Raphia hookeri, Napoleonaea vogelii, Piper guineense and Uapaca heudelotii. These plant-based coagulants showed similar performances as controls. R. hookeri and E. trifoliolata had reduction effects on iron and color of high colored water. These plants contained proteins, polysaccharides and tannins. Our findings show that plant-based coagulants, used in West Africa, may be applied to treat contaminated surface water to improve their quality for safe human drinking.     

统计技术在人工生态湿地净化水质中的应用

通过人工湿地对微污染河水水体的生态净化运行实例,介绍了改善城市供水水源的新途径。同时统计多个水质指标在水质净化过程中的变化规律（即净化前后的相关性）和水质指标大样本的统计规律,得出了现有人工湿地系统的净化效果,以期指导湿地系统的改进,并提高水质的净化效果。     

提高清水混凝土质量的主要技术措施和发展要求

本文通过介绍清水混凝土的发展状况和技术特点,针对其技术要求提出了为保证清水混凝土施工质量,在支撑系统、模板系统、钢筋工程、混凝土配比、浇筑和修补等主要技术环节应采取的主要技术措施和发展要求。     

The use of hydrogen peroxide for raising the efficiency of filter operation with biologically activated carbon

We have investigated the impact of hydrogen peroxide on the efficiency of biofiltration of the solutions of fulvic acids through biologically activated carbon with a native biofilm. We have also determined optimal conditions for using hydrogen peroxide in the processes of filtration through carbon. The use of H₂O₂ at the concentration 5 mg/dm³ is the most expedient since it makes it possible to enrich a solution of natural organic matter, in particular, fulvic acids with oxygen. It has been demonstrated that oxygen released during catalytic decomposition of H₂O₂ is actively consumed by microorganisms in the filter medium.     

Fluorescence properties of some farm wastes: implications for water quality monitoring.

Some farm wastes have been analysed for their fluorescence properties using fluorescence excitation-matrix (EEM) spectroscopy. Farm wastes investigated were silage liquor, pig and cattle slurry, and sheep barn waste. All farm wastes exhibited high intensities of fluorescence that can be attributed to the protein tryptophan. Silage liquor was characterised by a very high fluorescence intensity and an initial tryptophan: fulvic-like fluorescence intensity ratio of >20. Cattle and pig slurries exhibited a lower tryptophan : fulvic-like fluorescence intensity ratio (approximately 2-5) and lower tryptophan fluorescence intensity, and tyrosine fluorescence was also observed. Sheep barn wastes had the lowest tryptophan: fulvic-like fluorescence intensity ratios (approximately 0.5-4.0). Farm waste samples were reanalysed under controlled temperature conditions over a period of 50 days after sampling, to investigate the stability of their fluorescence properties. For silage liquor. tryptophan: fulvic-like fluorescence intensity ratios were observed to decrease with time, and were associated with a decrease in tryptophan fluorescence intensity, suggestive of clostridia breakdown of protein. For slurry samples. tryptophan: fulvic-like fluorescence intensity exhibited a more variable time-evolution, and tryptophan fluorescence intensity increased through time; the more complex fluorescence signal is due to the relatively heterogeneous nature of the slurry. Sheep barn waste samples exhibited more stable tryptophan: fulvic-like fluorescence intensity ratio and tryptophan intensities, suggesting these samples were more stable due to their greater age and decomposition. The ratios of tryptophan: fulvic-like fluorescence intensity observed from the farm wastes investigated are significantly higher than those observed in the majority of river waters, suggesting that farm waste pollution events could leave a signature in river waters due to their distinctively high protein fluorescence intensity.     

Implications of sequential use of UV and ozone for drinking water quality

The formation of bromate levels exceeding the drinking water standard of 10 microg L-1 may impose the reduction of ozone doses used in the treatment of drinking water. This paper illustrates the procedure of evaluating the use of reduced ozone doses while implementing an additional UV disinfection step for an actual drinking water treatment plant. Ozonation was performed at low ozone doses in bench-scale experiments with a pretreated river water from the Paris area (France). At the low ozone dose of 0.5 mg L-1, bromate formation could be kept below 0.4 microg L-1, while inactivation of vegetative bacteria and UV-resistant viruses was calculated to exceed 5 log units, and a substantial decoloration (31% of the absorption at lambda=254 nm) was achieved. Based on the measured transient ozone and OH radical concentrations, the oxidation of micropollutants was calculated. Fast reacting micropollutants containing phenol, amine or double bond moieties, such as sulfamethoxazole, diclofenac and 17-alpha-ethinylestradiol, were completely oxidized. Slow-reacting synthetic micropollutants, e.g., atrazine, iopromide and methyl tertiary butyl ether (MTBE), were oxidized by only 20%, 20% and 10%, respectively, and the taste and odor compounds 2-methylisoborneol (MIB) and geosmin by 40% and 50%, respectively. The addition of an UV treatment step to the existing treatment train, which should guarantee disinfection of ozone-resistant pathogenic microorganisms, including Cryptosporidium parvum oocysts, has negligible effects on water matrix components but may induce significant transformation of micropollutants. Overall, the combination of ozonation at reduced doses and UV treatment leads to an improved water quality with regard to disinfection, oxidation of micropollutants and minimization of bromate.     

生物活性炭对水的净化作用

世界各地已广泛采用粒状活性炭去除饮用水中的溶解有机物。在20世纪70年代发现细菌在粒状活性炭过滤器中滋生繁殖，可去除一些过滤器中的有机物。依据此项发现，预臭氧化被发现可以大大增强粒状活性炭的生物活性。臭氧化和粒状活性炭的组合使用一般被称为生物活性炭工艺，又称为生物增强型活性炭工艺。     

污水净化公司中水回用工程介绍

介绍了某市污水净化公司中水回用工程的设计内容，对污水处理厂的二级处理出水进行深度处理后回用于工业用水进行了探讨，经运行证明，该技术具有明显的社会效益和经济效益。     

The use of HEK 293 human cells for assessing water toxicity before and after purification of ions of copper and zinc

We have investigated the use of the viability index of the cells of the human embryo’s kidney of the NEK 293 line as a biomarker when assessing water toxicity before and after purification of Cu²⁺ and Zn²⁺. Addition to the incubation medium of the aqueous solution of copper sulfate results in a substantial decrease of the culture viability. An increase of the Zn²⁺ concentration does not produce any toxic effect on HEK 293 and HUVEC cells being cultivated. In the case of simultaneous introduction of ions of copper and zinc to the incubation medium the toxic effect of Cu²⁺ on the HEK 293 cells is absent while on endotheliocytes HUVEC persists. The procedure of water purification of ions of heavy metals was run concurrently with the use of synthetic and natural sorbents. The assessment on the HEK 293 cells of water toxicity after purification demonstrated high efficiency and safety of the composite material with active polysaccharide component.     

The use of fortified soil-clay as on-site system for domestic wastewater purification

The quest for simple, low-cost and high-performance decentralized wastewater treatment system for domestic application in developing nations necessitated this study. Clay samples collected from different deposits in Nigeria were characterized by studying the mineralogical and geochemical composition using X-ray diffraction (XRD) and atomic absorption spectroscopy (AAS), respectively. Three major clay minerals of kaolinite, illite and smectite were identified. The geochemical studies showed the abundance of SiO2, Al2O3 and H2O+ in each of the clay samples. Performance efficiency studies were conducted to determine the best combination ratio of pebbles/soil-clay. Soil-clay fortified by pebbles in combination ratios of 1:3 (i.e. pebbles:soil-clay = 1:3 (w/w) showed the optimum water purification, while the combination 3:1 gave the least. The flow rate studies showed that the wastewater had a longer residence time in non-fortified soil-clay than in fortified soil-clay. Two modes of treatment methods were employed-single and double column treatment methods (SCT and DCT). The two methods gave effluents of good quality characteristics, but those from the DCT were of better quality. The quality of effluents also varies from one clay type to another. The quality of effluents from media containing smectite clay mineral was better than those from other columns. Repeated usage of the fortified clay column showed a decrease of pH, TS and DO, and an increase of COD when monitored over a period of 10 days.     

Evaluating the use of minerals as forest fire retardants

The fire retardancy of carbonate minerals hydromagnesite, huntite and natural mixtures of hydromagnesite and huntite, on forest species was tested by analytical (differential thermogravimetry under air atmosphere) and laboratory-scale (flame spread test) methods. The selected forest species (Pinus halepensis Mill. and Cistus incanus L.) were collected from a wildland/urban interface zone near Athens and were treated with 5%, 10%, 15% and 20% w/w of the minerals. On the basis of differential thermogravimetric analysis, minerals decrease forest species combustibility (by increasing maximum weight loss rate and combustion duration) and consumability (by increasing combustion mass residue) and increase their sustainability (by increasing combustion duration). Additionally, the flame spread tests indicate that the minerals decrease forest species ignitability (increase time for ignition) and combustibility (decrease flame spread rate, maximum flame height and mean flame intensity), and affect their sustainability (by increasing the flame duration) and consumability (by increasing the mass residue). Among minerals examined, the most efficient retardant was the mixture of huntite and hydromagnesite.     

The potentials of some stabilizers for the use of lateritic soil in construction

Lateritic soil was stabilized with various percentages of rice husk ash (RHA), lime and cement. Atterberg limits, standard Proctor compaction, unconfined compression and California bearing ratio tests were carried out on lateritic soil with various percentages of these stabilizers in order to examine their influence. The required amounts of ash, lime and cement were determined for economical stabilization. This paper presents the potentials of rice husk ash compared to lime and cement in lateritic soil stabilization. For road construction, it recommends 7% cement for base materials, 5% lime for sub-base materials and 18% rice husk ash for sub-base materials.     

Optimisation of combined coagulation and microfiltration for water treatment

The effect of upstream coagulant dosing for full-flow microfiltration of an upland-reservoir water has been investigated. The process, run under conditions of constant flux and pH and based on a ferric salt, is compared with a published study of another full-flow process based on alum dosing and operated at constant pressure and coagulant concentration. The current study includes data for the residual deposit remaining following backflushing by reverse flow. Results are presented in terms of the specific-cake resistance (R'o, m(-2)) as a function of pH or coagulant dose. Reasonable correlation with classical cake filtration theory was obtained, such that R' was assumed to be independent of run time and cake thickness. The following trends have been noted: The optimum pH for the alum-based system appears to be between 7.5 and 8 on the basis of cake resistance. The effect of coagulant dose between 18 and 71 microM Fe3+ is much more significant than a change in pH between 5 and 9 for the alum system: a 53-fold increase in specific flux compared with a 7-fold increase with reference to the limiting R'o values at pH 4.8 and 7.7. A low coagulant dose (0.018mM, 1.0 mg l(-1) Fe3+) appears to have a slightly detrimental effect on downstream microfiltration operation. The low coagulant doses apparently cause incomplete aggregation of colloidal particles such that internal fouling of the membrane takes place. The residual (cleaning cycle) deposit resistance followed roughly the same trend as the backflush cycle-cake resistance with coagulant concentration, but with a much reduced value (about 16 times lower, on average). An optimum coagulant dose of 0.055 mM (3.1 mg/l) Fe3+ can be identified on the basis of operational cost based on coagulant cost and cake resistance, all other aspects of the system being substantially unchanged. It is concluded that coagulation with downstream microfiltration offers a cost-effective means of removing natural organic matter, achieving a THMFP removal of around 80% at the optimum dose.     

The use of light water for major aircraft fires

When a new extinguishing agent appears on the scene, existing agents become the yardsticks by which its performance is measured. The authors compared the relatively new Light Water foam with conventional protein foam and protein foam to which surface-active fluorocarbons had been added. Fire Research Station (JFRO) Note: Mr. Nash presented this paper at the 73rd Annual Meeting of the National Fire Protection Association on May 12, 1969 in New York City.     

The use of cationogenic SAS in pressure-driven processes of purification of water contaminated with Cr (VI) salts

The article has investigated the impact of cationogenic SAS on purification of contaminated waters of Cr (VI) by the methods of ultra and nanofiltration. We have determined the impact on these processes of the pH of the medium working pressure, and concentration of SAS concentration. The most effective results of water purification of Cr (VI) were obtained at pH 5 and SAS concentration close to its critical concentration of micelle formation.     

The effect of ozonation on natural organic matter removal by alum coagulation

Natural organic matter (NOM) was extracted from a moderately colored, eutrophic surface water source (Forge Pond, Granby, MA), and fractionated into quasi-homogeneous fractions. Fulvic acid (FA) and hydrophilic neutrals (HN) were the two most abundant NOM fractions that were isolated. Adsorption affinity of the isolated NOM fractions on preformed aluminum hydroxide flocs increased with increase in specific organic charge of the fractions, except for the two most highly charged fractions, FA and hydrophilic acids (HAA), which showed less adsorption affinity than expected based on their specific organic charge. Prior ozonation of FA and HN fractions resulted in a decline and an increase, respectively, in their adsorption affinity on aluminum hydroxide surface. Prior ozonation of Forge Pond raw water resulted in a progressive decline in dissolved organic carbon (DOC) removal by alum coagulation with increase in ozone dose. It appeared that ozone applied to raw water reacted preferentially with the humic fraction of NOM, resulting in the detrimental effects of ozonation on subsequent NOM removal by alum coagulation being magnified. Forge Pond raw water was pre-coagulated to remove humic substances. Ozonation of the pre-coagulated water demonstrated the beneficial effects of ozonation on the removal of non-humic NOM through alum coagulation. A strategy for staged coagulation with intermediate ozonation was proposed for waters containing both humic and non-humic NOM for maximum DOC and specific UV absorbance at 254nm (SUVA) removal.