Elaboración de una biorresina intercambiadora de cationes a partir de cáscara de plátano o guineo para eliminar metales pesados en agua contaminada / Preparation of a cation exchanger bioresin start from banana peel or guineo to remove heavy metals in polluted water

Esta investigación tuvo por objetivo obtener una bio-resina intercambiadora de cationes utilizando cáscaras de guineo o plátano, la cual reduzca la concentración de metales pesados en agua contaminada. A esta bio-resina se le realizaron pruebas fisicoquímicas: densidad seca aparente, pH y solubilidad en agua y solventes orgánicos. Se evaluó su efectividad filtrando agua contaminada con metales pesados, tales como hierro, cromo y níquel (Fe3+, Cr6+ y Ni2+), variando las condiciones de tiempo de contacto, temperatura y el tipo de cáscara. La cuantificación de la concentración de los metales en el agua filtrada se llevó a cabo por espectrofotometría visible. Se llegó a la conclusión que la bio-resina obtenida es efectiva para disminuir la concentración de metales pesados en agua, teniendo especial afinidad química por el cromo hexavalente; metal pesado que logró remover arriba del 90%. Las condiciones óptimas de operación de la bio-resina son a 30°C y 90 minutos de tiempo de contacto con la muestra. Además, las pruebas fisicoquímicas, permitieron tipificarla preliminarmente como una resina de intercambio catiónico débil con un grado de entrecruzamiento bajo.

This research aimed to obtain a cation exchange bio-resin, using plantain or banana peels, that reduces the concentration of heavy metals in contaminated water. The bio-resin underwent physico-chemical tests like apparent dry density, pH, solubility in water and organic solvents. Its effectiveness was tested by filtering contaminated water with heavy metals such as iron, chromium and nickel (Fe3+, Cr6+ y Ni2+) and by varying contact time conditions, temperature and type of peel. The measure of concentration of metals in filtered water was taken through visible spectrophotometry. We concluded that the resulting bio-resin is effective in reducing the concentration of heavy metals in water, showing special chemical affinity with hexavalent chromium, a heavy metal that was able to remove above 90%. The bio-resin optimum working conditions are 30°C and 90 minutes of contact with the sample. Also, the physico-chemical tests allowed to preliminary typify it as a weak cation exchange resin with a low degree of crosslinking.

Removal of malathion insecticide from water by employing acoustical wave technology

Organophosphorus pesticides are one of the most prevalent usages for pest control in the country. Such pesticides enter into water sources by different routes. Since drinking of contaminated water at the higher doses than the standard level, may causes undesirable effects to human health and ecosystem. The object of this research was to investigate the effect of various parameters including time, power and concentration on sonodecomposition of malathion insecticide in the water. The sonochemical degradation of malathion was investigated using acoustic wave technology [AWT]. AWT with 130 kHz was used to study the decomposition of insecticide solution. Samples were analyzed using HPLC at different intervals times. Effectiveness of AWT at different times [20, 40, 60, 80, 100, and 120 minutes], concentrations of malathion at 2, 4 and 8 mg/L as well as powers of device [300W, 400W, 500W] are compared. These findings showed that the degradation of the malathion insecticide at lower concentrations was greater in comparison to higher concentrations. Also, there was positive correlation between power increasing and the ability to malathion degradation. The sonodegradation of malathion at different concentrations and powers was successfully achieved. It has been shown that acoustical wave technology can be used to reduce the concentration of dissolved insecticide using high frequency

[Determination of corrosion and sedimentation potential in drinking water distribution system of Khorramabad city by corrosion indices and weight loss method]

According to the standard, drinking water must not be corrosive. Corrosive water solve primery materials of pipes, joints and valves in municipal water distribution systems and home plumbing systems and cause a lot of health, aesthetic and economic problems in water distribution systems. Thus, determination of corrosion potential of drinking water using methods which are feasible and reliable is necessary, and corrosion should be controlled in drinking water for water sanitation and health promotion among citizens. This research was carried out to determine water corrosivity or sedimentation potential in Khorramabad city, using corrosion indices. In this project 50 points as samples in two stages in the Summer and Autumn seasons were determined, and amount of corrosion indices, including Langelier Indice, Ryzener indice, Aggressive indice and Pokurious indice, corrosivity and temperature, calcium hardness, alkalinity, total dissolved solid and PH were calculated two times within a 3-month interval, then the data obtained from results were analyzed using SPSS software and statistical tests. Results of corrosion indices show that drinking water of Khorramabad is in equilibrium condition and has tendency to corrosion. Calculated corrosion indices are as follows: Langelier [-0.157], Ryzener [7.86], Aggressive [11.626], and Pokurious indice [7.65]. Statistical tests of Pearson and Spearman correlation coefficient don't indicate significant relationship between quality parameters with corrosion indices. Results of corrosion indices showed that drinking water of Khorramabad is inclined to corrosion

Scavenging of nickel and chromium toxicity in Aulosira fertilissima by immobilization: effect on nitrogen assimilating enzymes

The ubiquity of heavy metals in the biosphere results in the introduction of high amounts of toxic metals into the food chain from various sources. In the present study, one of the strongest nitrogen fixing cyanobacterium of the rice fields, Aulosira fertilissima, was subjected to nickel and chromium stress and the ameliorating effect of immobilization was investigated. Cell immobilization could protect the organism's growth against the toxicity of both heavy metals at LC50 as compared to lethal concentrations. The nitrate reductase activity in free cells treated with the metals was substantially inhibited but immobilized cells treated with 0.1 ppm nickel was not affected by the metal treatment. Cell immobilization also resulted in a significant protection against sub-lethal concentration of chromium but to a lesser degree than it did with sub- lethal levels of nickel. Control immobilized cells also had higher Nitrogenase activity than control free cells. Nickel and chromium addition markedly decreased the enzyme activity in free cells but immobilized cells exposed to sublethal concentrations of both metals could overcome this decrease. Glutamine synthetase showed similar response under immobilized conditions compared to free cells with both metals. The addition of algal filtrate in 3:1 ratio further increased the nitrogenase activity compared with immobilized cells treated with sublethal doses of both metals. Immobilization facilitated higher uptake of nickel as compared to chromium. The observations of the present study clearly demonstrate the protective effect of immobilization on Aulosira fertilissima against Nickel and chromium toxicity. Rice field ecosystem thus possess a bidirectional natural metal ameliorating system where Aulosira mats act as a naturally immobilized system and the decay of Aulosira along with other cyanobacteria act as natural chelators protecting the rice plants from deleterious effects of the heavy metals. Most importantly is...

Biological treatments of textile industrial effluents in Lagos metropolis, Nigeria.

The assessment of the effluents from two textile industries in Ilupeju in Lagos metropolis, Nigeria showed that they were high in conductivity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS) and contained traces of heavy metals like Ca, Zn but high concentrations of Cr and Pb. These wastewaters are normally discharged into neighbouring water bodies. Five bacterial groups, namely Micrococcus sp., Enterobacter sp., Alcaligens sp., Bacillus sp. and Acinetobacter sp. were isolated from these effluents. They were used individually for biotreatment and found to be able to utilize the components of the wastewaters for growth, Bacillus sp. and Acinetobacter sp. being the most efficient utilizers as they were able to reduce BOD to zero. The total viable count (TVC) increased significantly depicting growth of the bacterial population. The pH was regulated from 3.4-6.80 for NSF effluent and 12.2-10.29 for STI effluent. The work emphasises the level of industrial pollution in our environment as wastes are indiscrimately dumped into surrounding water bodies in urban areas, the textile industry being a case study. The treatment of any form of waste before disposal into the environment is important and ensures safety of the populace.

Decontamination of pollutants in aquatic system:2. adapting certain bacteria strains for organophosphorus pesticides degradation

Much effort has been given at the present to the use of microorganisms in the decontamination of organophosphorus pesticides [OP's]. Here we studied the role of repetitive exposure to low doses of OP and the influence of glucose as energy source on the activities of E. coli strains isolated from local environment for biodetoxification of OP. Results indicated that adapted E. coli strains were superior in their OP detoxification activity than wild. An isolated strain of E. coli from water samples [Wx2] showed the maximum activity among other strains for paraoxon biodetoxification. Adding glucose to the wild and adapted strains did not enhance their OP's biodegradation activities. Bioreactor column for OP's detoxification was build using promising adapted strain. The bioreactor achieved 57.49% biodegradation efficiency of the applied 0.1 mM paraoxon concentration. The efficiency of the bioreactor was maintained up to 30 days from its construction. The results suggest that adaptation of this strain of bacteria by exposure to the concentrations of the organophosphate insecticides can enhance its efficiency in degradation of these compounds that may introduced an efficient, cheap and environmental friendly technique for pollutants decontamination

Results based on global experience of monitoring crop protection products in water

The pesticides for which the most expensive data on use are currently available are those applied in agricultural settings. Similarly, the majority of information on pesticide detections in ground water has been collected for pesticides used within predominantly agricultural areas. The available data indicate that the pesticides detected most frequently in ground water are also those used widely in agriculture, namely, the triazines and acetanilides. Some of the more heavily used insecticides and fumigants, such as aldicarb, DBCP, and EDB, have also been among the pesticides detected most often in ground water. For those detected, pesticide detections in ground waters generally become more common with greater use and greater analysis. Direct relations between pesticides detection frequencies and use become more evident when data on pesticide use are aggregated over smaller areas. When pesticide use is assessed at comparatively large spatial areas, low use is typically associated with low frequencies of pesticide detection in ground water, while high use is associated with a broad range of detection frequencies. A comprehensive review of published information on the distribution of pesticides in ground water indicates that pesticides from various chemical classes heve been detected in ground water. Many of these compounds are commonly present at low concentrations in shallow ground water immediately beneath agricultural land. Information on pesticides in ground water is not sufficient to provide either a statistically representative view of pesticide occurence in ground water across various countries or an indication of long-term trends or changes in the severity or extent of this contamination over time.This is largely due to wide variations in analytical detection limits, site selection procedures, and other design features among studies conducted in different countries at different times. Past approaches have not been well suited for distinguishing "point source" from "no-point source" pesticide contamination. Among the variety of natural and anthropogenic factors examined, those that appear to be most strongly associated with the intensity of pesticide contamination of ground water are the depth, construction, and age of the sampled wells, the amount of the recharge (precipitation or irrigation), and the depth of the tillage, proximity to surface water (gw/sw interactions) are responsible for a huge number of detections, since surface run-Off...

O controle de trihalometanos (THM) nas águas de abastecimento público / Control of trihalomethanes in public water supplies

Apresenta uma revisäo bibliográfica, onde foram reunidos grande parte dos fundamentos teóricos sobre o tema. Inclui um conjunto de informaçöes sobre as pesquisas publicadas no período de 1980 a 1988, oriundas de literatura americana. O conjunto de informaçöes apresenta alguns pontos de vista ingleses e canadenses. Destacou-se as técnicas menos difundidas, onde a análise da literatura foi mais aprofundada. Reuniu-se as experiências desenvolvidas pela SABESP nos últimos anos, com informaçöes sobre as pesquisas em andamento e as que se espera por em prática em futuro próximo. Expôs-se um estudo de caso para a Baixada Santista que consistiu em dar-se um tratamento estatístico e discussäo dos resultados de análises dos últimos três anos. A interpretaçäo e conclusöes foram baseadas na parte teórica e nas observaçöes das experiências dos últimos anos.