As disinfection by-products, the taste and odor (T&O) compounds were produced by chlorination at the end of water treatment. The existence of T&O compounds causes the pipe water with unpleasant odor and reducing water quality. Based on the latest research achievements at home and abroad, the characteristics and formation mechanisms of typical T&O compounds produced by chlorination are introduced. The new analytical method of electronic nose is also expounded. In addition, the common control technologies, such as pre-oxidation, activated carbon adsorption and bio-membrane, are reviewed. Since the precursors of T&O compounds shows small molecular, stable structure and low concentration, some coupling technologies including ozone-GAC, permanganate-PAC, and bio-membrane and GAC treatments, are employed effectively.Key words: chlorination; odor and taste compounds; disinfection by-products; precursor; electronic nose
Fishy odor, part of the taste and odor existing in the drinking water, often cause people to reflect poor water quality, and even lead to social panic. The typical fishy compounds are primarily amines and polyunsaturated aldehydes (PUAs), which are widely found in surface water, particularly during the algae blooms. The properties of the small molecular weight, low odor threshold and difficult removing, have received a great concern in the field of environment protection. Because of their environmental hazards, the source, physical-chemical properties, genotoxicity and generation mechanism of the fishy compounds were introduced in this paper in order to remove the compounds by controlling the precursors and generation pathway. The results show that amines are produced by the nitrogenous compounds in catalysis of microorganisms and enzymes, while PUAs are produced by polyunsaturated fatty acids (PUFAs). The algal cells cleavage is a key factor of producing fishy odor.
Experiment was made,in which Harbin reservoir water was taken as source water to observe the influence of chlorination conditions such as chlorine dosage,reaction time,pH value,organics concentration and varieties of disinfectant on the amount of THMs formation.Based on the experiment results,control measures were proposed for the formation of disinfection byproducts such as THMs through optimization of disinfection.
The leak detecting-ball moving in pipes combined the sensors of the acoustic leak detection achieves the high responsiveness to small leaks of the water distribution system (WDS). The dynamic characteristics of the single sphere moving inside pressure pipes are studied for optimal design of the leak detecting-ball. The experimental balls having different densities are made of three types of material by using 3D printing, including tetrafluoroethylene (ETFE), photosensitive resin (PR) and wax. The balls have densities from 1.06 to 1.35 and different diameters, ball-to-pipe diameter ratios from 0.32 to 0.5. The Reynolds numbers of the pipe flows are from 1400 to 50000. The moving velocity of the balls with different pipe flow velocities, ball densities, and ball-to-pipe diameter ratios are investigated through the laboratory experiments. The velocities of balls in some of the experimental tests are greater than the average flow velocity. These larger balls rolled faster than the average flow velocity because of the maximum thrust by the pressure flow in the center of the circular tube section.
Experiment was made,in which Harbin reservoir water was taken as source water to observe the influence of chlorination conditions such as chlorine dosage,reaction time,pH value,organics concentration and varieties of disinfectant on the amount of trihaloacetic acids formation.Based on the experiment results,control measures were proposed for the formation of disinfection byproducts such as trihaloacetic acids through optimizat ion of disinfection.
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