Nano-Photocatalysts in the Treatment of Colored Wastewater - A Review

2012 ◽  
Vol 734 ◽  
pp. 349-363 ◽  
Author(s):  
Neetu Divya ◽  
Ajay Bansal ◽  
Asim K. Jana
Keyword(s):  
Organic Compounds ◽  
Health Hazard ◽  
Water System ◽  
Ultra Violet ◽  
Industrial Effluents ◽  
Agricultural Runoff ◽  
Aquatic Life ◽  
Chemical Spills ◽  
Colored Wastewater ◽  
Complex Organic

In the present scenario, the problem of water pollution is remarkable. The need to maintain clean water for both flora and fauna has become a major, even a critical concern. A large number of organic substances are introduced into the natural water system from various sources such as industrial effluents, agricultural runoff and chemical spills. Textiles industries specifically pollute the water sources due to the random use and discharge of various types of dyes. It may significantly affect photosynthetic activity in aquatic life and their presence in drinking water constitutes a potential human health hazard. It is therefore essential either to remove the dyes from water or to treat them in such a way so as to minimize their effects on the environment and also to decolorize the water. Various research works on different processes are reviewed and discussed in the present article. It has been observed that the advanced oxidation processes are used widely to degrade the organic compounds in water. Photocatalytic systems are effective for the degradation of many unwanted complex organic compounds through the use of efficient nanophotocatalysts activated under ultra-violet (UV) irradiation.

The Contribution of Agricultural Loading to Eutrophication in Finnish Lakes

1985 ◽  
Vol 17 (6-7) ◽  
pp. 1133-1140 ◽  
Author(s):  
L. Kauppi
Keyword(s):  
Algal Growth ◽  
Industrial Effluents ◽  
Agricultural Runoff ◽  
Total Surface Area ◽  
Ionic Concentration ◽  
Phosphorus Loading ◽  
Available Phosphorus ◽  
Agricultural Activity ◽  
Nineteen Seventies ◽  
Spring Maximum

Agriculture accounts for 9 per cent of the total surface area of Finland and generates the greatest single nutrient input to Finnish watercourses. Since agricultural activity is scattered throughout the whole country its effects in lakes are less pronounced than those of domestic and industrial effluents. On the other hand, point source phosphorus loading of lakes and rivers decreased significantly during the nineteen-seventies. Phosphorus is the nutrient which primarily limits production in most Finnish lakes. The availability of phosphorus in agricultural runoff waters is therefore a crucial question in the evaluation of the eutrophicating effects of agriculture. Our results indicated that in runoff waters available phosphorus can be 60-70 per cent of the total phosphorus. However, the concentrations of available P were so low that they could be achieved in Finnish lakes of low ionic concentration through simple chemical desorption without the assistance of the algal uptake. The utilization of the spring maximum of runoff phosphorus in lakes would thus not depend on the concurrence of the maxima of loading and algal growth.

Wastewater treatment and nutrient removal in the combined reactor

1998 ◽  
Vol 38 (1) ◽  
pp. 87-95 ◽  
Author(s):  
M. Roš ◽  
J. Vrtovšek
Keyword(s):  
Organic Compounds ◽  
Industrial Wastewater ◽  
Design Procedure ◽  
Order Reaction ◽  
Treated Wastewater ◽  
Nitrification Rate ◽  
Zero Order Reaction ◽  
Aerobic Reactor ◽  
Complex Organic

A combined anaerobic anoxic aerobic reactor for the treatment of the industrial wastewater that contains nitrogen and complex organic compounds as well as its design procedure is presented. The purpose of our experiments was to find a simple methodology that would provide combined reactor design. The reactor is based on the combination of anaerobic, anoxic and aerobic process in one unit only. It was found that the HRT even under 1 hour in the anaerobic zone is long enough for the efficient transformation of complex organic compounds into readily biodegradable COD which is then used in dentrification process. In the N-NO3 concentration range 1.5-50 mg/l the denitrification rate could be expressed as half-order reaction when the CODrb was in excess. N-NO3 removal efficiency is controlled by the recycle flow from the aerobic to the anoxic zone. Nitrification rate can be expressed as first, half or zero-order reaction with respect to effluent N-NH4 concentration. Nitrification rate depends on the dissolved oxygen concentration and hydrodynamic conditions in the reactor. Case study for design of a pilot plant of the combined reactor for treatment of pre-treated pharmaceutical wastewater is shown. Characteristics of pre-treated wastewater were: COD=200 mg/l, BOD5=20 mg/l, N-Kjeldahl=80 mg/l, N-NH4=70 mg/l, N-NOx<1 mg/l, P-PO4=5 mg/l. Legal requirements for treated wastewater were: COD=<100 mg/l, BOD5<5 mg/l, N-NH4=<1 mg/l, N-NOx=<10 mg/l.

Chemical Recognition and Nematocyte Excitation in a Sea Anemone

1979 ◽  
Vol 83 (1) ◽  
pp. 283-292
Author(s):  
ROGER LUBBOCK
Keyword(s):  
Chemical Composition ◽  
Organic Compounds ◽  
Mechanical Stimulation ◽  
Sea Anemone ◽  
Physical Contact ◽  
Recognition Process ◽  
Chemical Recognition ◽  
Cellular Recognition ◽  
Complex Organic ◽  
Stichodactyla Haddoni

The response of nematocytes in the anemone Stichodactyla haddoni to contact with complex organic compounds varies according to the 9ubstance concerned and in most cases according to the level of accompanying mechanical stimulation. Compounds with a proteinaceous moiety differ in their capacity to excite nematocytes, but usually tend to induce a stronger response than polysaccharides or lipids. Nematocyst discharge against foreign animals appears to be the result of a sophisticated cellular recognition process in which the nematocytes, and/or cells closely associated with them, respond to physical contact with a surface of appropriate chemical composition.

scholarly journals Seasonal assessment, treatment and removal of heavy metal concentrations in a tropical drinking water reservoir

2016 ◽  
Vol 35 (2) ◽  
pp. 103-113 ◽  
Author(s):  
Moshood Keke Mustapha ◽  
Joy Chinenye Ewulum
Keyword(s):  
Heavy Metals ◽  
Drinking Water ◽  
Best Management Practices ◽  
Management Practices ◽  
Anthropogenic Activities ◽  
Health Hazard ◽  
Water Reservoir ◽  
Industrial Effluents ◽  
High Concentration ◽  
Agricultural Materials

AbstractHeavy metals are present in low concentrations in reservoirs, but seasonal anthropogenic activities usually elevate the concentrations to a level that could become a health hazard. The dry season concentrations of cadmium, copper, iron, lead, mercury, nickel and zinc were assessed from three sites for 12 weeks in Oyun reservoir, Offa, Nigeria. Triplicate surface water samples were collected and analysed using atomic absorption spectrophotometry. The trend in the level of concentrations in the three sites is site C > B > A, while the trend in the levels of the concentrations in the reservoir is Ni > Fe > Zn > Pb > Cd > Cu > Hg. Ni, Cd, Pb and Hg were found to be higher than the WHO guidelines for the metals in drinking water. The high concentration of these metals was from anthropogenic watershed run-off of industrial effluents, domestic sewages and agricultural materials into the reservoir coming from several human activities such as washing, bathing, fish smoking, especially in site C. The health effects of high concentration of these metals in the reservoir were highlighted. Methods for the treatment and removal of the heavy metals from the reservoir during water purification such as active carbon adsorption, coagulation-flocculation, oxidation-filtration, softening treatment and reverse osmosis process were highlighted. Other methods that could be used include phytoremediation, rhizofiltration, bisorption and bioremediation. Watershed best management practices (BMP) remains the best solution to reduce the intrusion of the heavy metals from the watershed into the reservoir.

scholarly journals BTX Removal from Open Aqueous Systems by Modified Cellulose Fibers and Evaluation of Competitive Evaporation Kinetics

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3154
Author(s):  
Antonio Tursi ◽  
Francesco Chidichimo ◽  
Rita Bagetta ◽  
Amerigo Beneduci
Keyword(s):  
Organic Compounds ◽  
Low Cost ◽  
Water System ◽  
Open Water ◽  
Cellulose Fibers ◽  
Petroleum Products ◽  
Pollutant Concentrations ◽  
Surface Modified ◽  
Adsorption Desorption ◽  
Modified Cellulose

BTX stands for Benzene, Toluene, and Xylenes, which are volatile organic compounds contained in petroleum products such as gasoline. They have negative health effects and are sadly known for soil, air, and water contamination. This paper provides an investigation on BTX removal from open water systems like those represented by natural water bodies. In such systems, the evaporation process takes place, stealing the pollutants from the aqueous matrix by transferring them into the air, resulting in a secondary pollution. To prevent this situation, adsorption of these organic compounds on cellulose fibers, extracted from Spanish Broom vegetable, was studied. Raw and surface modified cellulose fibers were used for this purpose. The second ones were hydrophobized by two different green and low-cost functionalization systems (no solvent urethane functionalization and low pressure plasma treatments). Batch experiments were performed in an open system where BTX underwent two competing removing mechanisms: volatilization, and adsorption/desorption on/from the fibers dispersed in the water system. A mathematical model was implemented for the interpretation of the observed time-varying pollutant concentrations and the estimation of the kinetic constants for adsorption, desorption, and evaporation. The developed model, provided with the aforementioned parameters calibrated for each type of fibers, was then used for the prediction of their adsorption capacities both into open and closed systems.

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