Variability in phosphorus binding by aluminum in alum treated lakes explained by lake morphology and aluminum dose

Sediment cores from six aluminum sulfate treated lakes in Minneapolis, MN were analyzed to determine the effectiveness of phosphorus (P) binding by aluminum (Al). Two of the study lakes are polymictic and the remaining four are dimictic. Above background concentrations of Al and Al-bound-P (P_Al) were detected in all six lakes at varying sediment depths. In contrast to previous studies, however, the binding relationship between Al and P was not consistent between lakes and substantial variation was also detected within each sediment profile. Average lake sediment Al:P_Al ratios ranged from 5.6 to 15 (molar) with higher ratios, or less efficient P binding, generally being detected in deep, dimictic lakes with high sediment Al content due to treatment. Multiple linear regression was used to explain the variability among average Al:P_Al ratios detected in each core and a lake morphometry index (Al Depth Index, core collection depth divided by the square root of lake area) along with Al dose described most of the variation (92%). Even though P bound to the added Al appears to be permanently removed from the internal P cycle in each lake (as evidenced by burial with new sediment), the differences in binding efficiency may indicate lower P inactivation, on a per unit Al basis, when elevated amounts of Al are added to the sediment, especially in deeper areas of lakes where sediment focusing may cause elevated Al accumulation to occur.     

Phosphate removal in acidified and limed lake water

Biotic and abiotic removal of phosphate from lake water from the acidified Lake Gårdsjön as well as immediate changes in these processes upon liming were tested in laboratory experiments. Phosphate was added and analyses of particulate material from both sterilized and nonsterilized series permitted determinations of biotic uptake as the difference between the series. In the original lake water (pH 4.7) biotic uptake largely dominated phosphate removal and abiotic precipitation was of minor importance.In the limed series at pH 7.2 the results had changed and abiotic precipitation dominated the phosphate removal and biotic uptake was strongly reduced. Of the analysed metals, Ca, Mn, Fe and Al, only Fe and Al occurred in the particulate material. The coprecipitation of phosphate and iron was probably due to adsorption on iron hydroxide at both pH values. The nature of phosphorus-aluminium precipitates is largely unknown but different possible complexes are discussed as well as the relative importance of iron and aluminium precipitates.Application of the results in relation to the ongoing lake liming and phosphorus fertilization are discussed.     

Kinetics of inactivation of adenovirus in water by chloramine-T

The use of chloramine-T (CAT) as a possible alternative to chlorine, which forms genotoxic trihalomethanes during the disinfection of water, was examined. Kinetics of inactivation of adenovirus type 3 in buffered water by CAT were performed to determine the viricidal potential of CAT. The viral inactivation curves showed two stages. The initial linear part of each curve represented pseudo-first-order kinetics with the test virus. A dose-response relationship between CAT concentration and 99% adenovirus inactivation time was demonstrated. The rate of inactivation of the virus by CAT decreased with increase in pH of water. The inactivation followed first-order kinetics in [CAT] and fractional-order in [H⁺] or inverse fractional-order in [OH⁻]. The effect of ultrasonication or of salts on the inactivation rate was significant at pH 6 and negligible at pH 10, suggesting that the viral aggregation is greater in acidic than in alkaline water. Inactivation kinetics were also performed at different temperatures and Arrhenius and thermodynamic parameters were evaluated. Our results show that the rate of inactivation of adenovirus type 3 by CAT was faster in slightly acidic than in alkaline water suggesting that as an alternative disinfectant to chlorine, CAT would be more effective in slightly acid water.     

Controlling eutrophication by combined bloom precipitation and sediment phosphorus inactivation

The hypothesis that the combination of the flocculent polyaluminium chloride (PAC) with the lanthanum-modified bentonite Phoslock^® (Flock & Lock) could sink effectively a water bloom of cyanobacteria and could shift a turbid, cyanobacteria infested lake to a clear water lake was tested in a controlled laboratory experiment and a whole lake experiment. In the laboratory, a relatively low dose of the flocculent PAC (2.2 and 4.4 mg Al l⁻¹) was insufficient to sediment positively buoyant cyanobacteria (Microcystis aeruginosa). Similarly, the lanthanum modified clay (dosed at 390 mg l⁻¹) was insufficient to sediment the positively buoyant cyanobacteria. However, the combination of PAC and Phoslock^® effectively sedimented cyanobacteria flocks. Likewise, a combined treatment of 2 tons PAC and 18 tons Phoslock^® in Lake Rauwbraken in April 2008 effectively sedimented a developing cyanobacteria bloom of Aphanizomenon flos-aquae. The average chlorophyll-a concentration in the two years prior to this Flock & Lock treatment was 19.5 (±36.5) μg l⁻¹, while it was as low as 3.7 (±4.5) μg l⁻¹ in the years following the treatment. The combined treatment effectively reduced the amount of total phosphorus (TP) in the water column from on average 169 (±126) μg P l⁻¹ before the application to 14 (±15) μg P l⁻¹ after the treatment. Based on mean summer chlorophyll-a and TP concentrations, the lake was shifted from a eutrophic/hypertrophic state to an oligo/mesotrophic state. From directly after treatment in April 2008 until and including 2013, Lake Rauwbraken remained in an oligo-mesotrophic clear water state with TP reduced to less than 10% of the pre-treatment. This result shows that eutrophication in relatively small, isolated, stratifying lakes can be restored by targeting both water column and sediment P using a combination of flocculent and solid phase P-sorbent.     

Endotoxin inactivation by selected drinking water treatment oxidants

Exposure to endotoxins in treated drinking water can occur through ingestion, dermal abrasions, inhalation of water vapor, intravenous injection or during dialysis. While the risks associated with endotoxin ingestion and entry through dermal abrasions are not well quantified, adverse effects of intravenous injection and dialysis are well known and some studies indicate that inhalation of moisture-laden air may impact human health. This study quantifies the inactivation of endotoxin derived from Escherichia coli O55:B5 by three substances used either as disinfectants or oxidants in drinking water treatment: chlorine, monochloramine and potassium permanganate. Inactivation rates were found to be 1.4, 1.0 and 0.7 endotoxin units (EU)/mL h, for free chlorine, potassium permanganate and monochloramine, respectively. These rates are relatively slow given that contact times in drinking water distribution systems are typically less than 48 h. While small amounts of endotoxin may be removed by oxidation the observed removals are much less than those provided by physical removal processes. The significance of this finding is important for dialysis considerations but is as yet unclear with regard to inhalation, as the risk of inhaling sufficient quantities of endotoxin-containing aerosolized water droplets to adversely affect human health has not yet been adequately quantified.     

Reductions in inactivation rates of bacteriophages by clay minerals in lake water

Differences were noted in the rate of inactivation of bacteriophages in natural lake water, with the sequence of lability being φ11M15 of Staphylococcus aureus RN450, Qβ of Escherichia coli K-38 > 80α of S. aureus RN450 > P1 of E. coli B > T1 of E. coli B. The survival of φ11M15 in lake water was unaffected by autoclaving, filtration, or amendment with particulate humic acids or heat-killed cells of Erwinia herbicola, Sarcina lutea, and Saccharomyces cerevisiae. However, in the presence of attapulgite and vermiculite and, to a lesser extent, montmorillonite and kaolinite, the rate of inactivation of φ11M15 in natural, autoclaved, or filtered lake water was greatly reduced.     

Mechanisms of inactivation of hepatitis A virus in water by chlorine dioxide

In this study, to elucidate the mechanisms of inactivation of hepatitis A virus (HAV) by chlorine dioxide, cell culture, enzyme-linked immunosorbent assay (ELISA), and long-overlapping RT-PCR were used to detect the infectivity, antigenicity, and entire genome of HAV before and after disinfection. The results revealed the complete inactivation of infectivity after a 10-min exposure to 7.5mg of chlorine dioxide per liter; and the highest level of sensitivity in the 5'non-translated regions (5'NTR) (the sequence from bp 1 to 671), inactivation of which took as much time as the inactivation of infectivity of HAV by chlorine dioxide; the complete destruction of antigenicity after a 10-min exposure to 7.5mg of chlorine dioxide per liter. It is suggested that the inactivation mechanism of HAV by chlorine dioxide was due to the loss of the 5'NTR and/or destruction of the antigenicity, which is not similar to that of chlorine (Appl Environ Microbiol 68: 4951).     

Errors in gran function analysis of titration data for dilute acidified water

Errors that result from applying simple Gran function analysis to titration data from typical dilute acidified surface waters are discussed. Theoretical development and experimental verification of these errors are presented. The results of this study show that strong acid acidity is almost always overestimated and weak acid acidity is underestimated. Further, if CO₂ contamination of the titrant is present, total acidity will be overestimated.     

Influence of water and sediment quality on benthic biota in an acidified river

Water and sediment quality and benthic biota were investigated in all seasons during three years in the River Akagawa that receives the effluent from a mine drainage treatment plant at its upstream site. The upper reaches kept the low pH, the comparatively high concentrations of metals and a large amount of iron deposited on the riverbed. The predominant macroinvertebrates were Protonemura sp., Capnidae, Nemoura sp. and Chironomidae in the upper and middle reaches. In the lowest reaches, the community structure of the macroinvertebrate changed into Chironomidae, Trichoptera (Hydropsychidae) and Ephemeroptera (Baetis sp.) as the pH was increased. From the results of multivariate analyses, it was found that the restoration of pH and attached algae and the increase in the concentrations of nutrients and organic matter promoted the inhabitation of Chironomidae and Hydropsychidae, whereas the dissolved metals in the river water inhibited the inhabitation of these families. Moreover, the sedimentation of metals would cause a severe damage to the inhabitation of Hydropsychidae compared with that of Chironomidae.     

铝盐深度除磷实验研究

研究了化学除磷常用铝盐单独投加和铝盐与PAM协同作用的除磷效果,并确定了铝盐除磷的最佳反应条件,研究表明,铝盐具有良好的除磷效果,对废水中磷的去除率较高,PAM则能显著提高铝盐的除磷效果。     

Synergistic inactivation of Cryptosporidium parvum using ozone followed by free chlorine in natural water

The synergistic effect of sequential exposure to ozone followed by free chlorine on inactivation of Cryptosporidium parvum oocysts suspended in natural waters was studied in bench-scale batch reactors. Animal infectivity using neonatal CD-1 mice was used to measure oocyst inactivation. The synergistic effect measured in two alkaline (pH 8.1) natural waters was statistically significant but was considerably smaller than previously reported in buffered de-ionized water at pH 6.0. Temperature, ozone primary treatment level, and water type did not have measurable impacts on the synergistic effect. Efforts to increase the synergistic effect by reducing the pH from 8 to 6 by acid addition were unsuccessful. In the two low alkalinity (pH 6.0) natural waters tested, the measured synergistic effect was greater than in the alkaline waters, but was still less than that measured previously in buffered de-ionized water. It was concluded that the synergistic effect reduction in the natural waters tested was due in part to alkalinity and in part to other unidentified water quality characteristics. Sequential treatment with ozone followed by free chlorine may only be a feasible strategy for achieving synergistic C. parvum inactivation credit for water treatment facilities with natural waters having a low pH (near 6.0).     

Investigation of phosphorus removal from water

The removal of different phosphate compounds from water and waste water by precipitant was investigated. Calcium hydroxide precipitated orthophosphate with greater efficiency than aluminium sulphate, while aluminium sulphate gave better efficiency in the removal of polyphosphates. Calcium hydroxide was not able to precipitate the phosphate in glucose phosphate—and aluminium sulphate effects only a slight precipitation. Bentonite and polyelectrolyte (partly anionic type), in conjunction with aluminium sulphate, gave an increased phosphate reduction, settling velocity, a decreased turbidity of the liquid and a decreased sludge volume.

In the case of waste water, considerably better results were achieved due to the high content of suspended matter, which helped to bind the phosphate compounds into flocs. The use of bentonite and polyelectrolyte in treating waste water gave better results and better results were also obtained when calcium hydroxide was used alone for precipitation.     

Virus inactivation by silver doped titanium dioxide nanoparticles for drinking water treatment

Photocatalytic inactivation of viruses and other microorganisms is a promising technology that has been increasingly utilized in recent years. In this study, photocatalytic silver doped titanium dioxide nanoparticles (nAg/TiO₂) were investigated for their capability of inactivating Bacteriophage MS2 in aqueous media. Nano-sized Ag deposits were formed on two commercial TiO₂ nanopowders using a photochemical reduction method. The MS2 inactivation kinetics of nAg/TiO₂ was compared to the base TiO₂ material and silver ions leached from the catalyst. The inactivation rate of MS2 was enhanced by more than 5 fold depending on the base TiO₂ material, and the inactivation efficiency increased with increasing silver content. The increased production of hydroxyl free radicals was found to be responsible for the enhanced viral inactivation.     

Chromatographic determination of pesticide 2,4-D in water bodies

New silica-based adsorbent with covalently immobilized groups of triton X-100 has been proposed for extraction and concentration of 2,4-dichlorophenoxyacetic acid (2,4-D) from water bodies. The recovery of this pesticide into adsorbent phase occurs in the form of its ionic associate with cationic surfactants (CSAS). It was shown that the application of cetyltrimethylammonium bromide made it possible to achieve the pesticide extraction ratio as high as 94%. Elution with acetonitrile allows us to achieve a 50-fold absolute concentration of 2,4-D making it possible to perform its determination by the high performance liquid chromatography method with ultraviolet detection, where the detection level is 0.07 mg/dm³ and the linearity range is from 0.09 to 0.20 mg/dm³.     

An improved method of phosphorus analysis in sea water

A reagent for the determination of phosphorus in sea water which contains Mo(VI) plus Mo(V) may be easily prepared by the reduction of Mo(VI) with metallic zinc in acid medium. This reagent is stable in the air for several months, and the development of the molybdenum blue colour is complete in 20 min at about 100°C; the colour is stable for at least a few months. The salt error is approximately 5 per cent with sea water of chlorinity 19 per milli. The interference due to either arsenate or silicate at their concentrations in sea water is negligible.     

降低饮用水中残余铝的中试研究

研究了水处理过程中铝含量的影响因素和控制条件,结果表明:对水中铝含量的影响PAC投加量＞pH＞滤速＞活化硅酸投加量.控制余铝的最佳条件是:PAC投加量2.0 mg/L,pH值7.5,活化硅酸投加量1.5 mg/L,滤速8.0 m/h.过滤阶段对铝的影响小于混凝阶段,水厂实际运行时应尽量采用低滤速.为控制出厂水铝含量,建...     

Inorganic aluminium-hydrogen ion relationships for acidified streams; the role of water mixing processes

Streamwaters draining acidified catchments usually exhibit large fluctuations in aluminium and hydrogen ion concentrations which are positively correlated with flow: stormflow waters are mainly derived from waters passing through the upper acidic and aluminium bearing soil zones; baseflow waters are derived from the lower soil/groundwater zones where inorganic reactions prevail and hydrogen ions generated in the upper soil horizons are consumed. In several cases these variations in streamwater chemistry cannot be explained by solubility control of a single mineral phase such as microcrystalline or natural gibbsite. Here, for three such catchments, the controlling mechanisms are explored in terms of both conservative and non-conservative two-component mixing of upper soil and ground waters. For this exercise linear concentration plots are the best tools; the commonly used log-log plots lead to a confounded picture masking important insights.     

Accelerated reoxygenation of water bodies using hydrogen peroxide

This paper reports a laboratory study of an accelerated reoxygenation treatment of polluted water bodies, using hydrogen peroxide (H₂O₂): conditions such as the discharge of waters from domestic sewers or polluted storm-water resulting from intense rainfall that lead to a reduction in the level of dissolved oxygen (DO). We studied the water from rivers that make up the basin of the Lagoa Rodrigo de Freitas (LRF) lagoon, Rio de Janeiro, Brazil. When intense rainfall coincides with discharge from sewers, the polluted water may reach LRF. This has in the past led to episodes of critical deficit in DO in the waters of the lagoon, resulting in fish kill. To study this, we carried out experiments with water samples taken from the river feeding the lagoon. To study the accelerated reoxygenation of the river waters, we used different doses of H₂O₂. We concluded that the addition of H₂O₂ to the waters of the river during polluting events can prevent the level of DO in the lagoon going below a critical value. This treatment resulted in an immediate increase in DO that lasted hours and in the sustainability of the DO above the legal limit 5.0 mg L^?1, enough to avoid fish kill.     

Hepatitis a virus and poliovirus 1 inactivation in estuarine water

The hepatitis A virus (HAV) and poliovirus 1 were added to estuarine water samples and their stability in maintenance medium was compared to that in water samples untreated and treated by heat and filtration. The inactivation curves show that the inactivating factor is biological in nature.     

Improvement of organics removal by bio-ceramic filtration of raw water with addition of phosphorus

The purpose of this study was to investigate the effect of phosphorus addition on biological pretreatment of raw water. Experiments were conducted in pilot-scale bio-ceramic filters with raw water from a reservoir located in Beijing, China. The results demonstrated that phosphorus was the limiting nutrient for bacterial growth in the raw water investigated in this study. The measured values of bacterial regrowth potential (BRP) and biodegradable dissolved organic carbon (BDOC) of the raw water increased by 50-65% and 30-40% with addition of 50 microg of PO4(3-)-PL(-1), respectively. Addition of 25 microg of PO4(3-)-PL(-1) to the influent of bio-ceramic filter enhanced the percent removal of organics by 4.6, 5.7 and 15 percentage points in terms of COD(Mn), TOC and BDOC, respectively. Biomass in terms of phospholipid content increased by 13-22% and oxygen uptake rate (OUR) increased by 35-45%. The ratio of C:P for bacteria growth was 100:1.6 for the raw water used in this study. Since change of phosphorus concentrations can influence the performance of biological pretreatment and the biological stability of drinking water, this study is of substantial significance for waterworks in China. The role of phosphorus in biological processes of drinking water should deserve more attention.