By-products of water disinfection

Three oxidants have found wide acceptance in water disin-fection-chlorine, chlorine dioxide and ozone. Of these, chlorine has been preferred for the past decades. Unfortunately, chlorine has the inherent disadvantage of reacting with the micropollu-tants present in the water to produce derivatives of the halogen group, which are all cancerogenic or mutagenic compounds. Thus, in order to overcome the problem of chlorine derivative formation, the use of ozone as disinfectant has become more and more frequent. But it soon became obvious that the reaction of ozone with water pollutants yielded equally hazardous pro ducts, mostly carbonyl derivatives and bromoacetonitriles. Although ozone is a strong biocide, it is seldom used singly because of its instability. The most frequent use of ozone as disinfectant is in combination with chlorine or chlorine dioxide, which, again leads to the formation of a number of toxic by-products. The mechanisms tfiat govern the production of these toxic species or are responsible for their toxicity have not been satisfactorilyexplainedyet. The authors of the present paper provide adetailed account of the chemical compounds produced in a variety of Poland's waterworks in the course of the disinfection process. Particular consideration is given to the water treatment plants of the city of Warsaw, where use is made of chlorine, ozone and chlorine dioxide as disinfectants. Presented are also the potentialities for determining the by-products in potable water

Determination of haloacetonitriles (HANs) in drinking water

A method was developed, in which HANs in potable water are determined by solid phase microextraction (SPME). The analytical procedure is relatively quick and simple, yielding satisfactory recoveries, which range between 80% and 90%. The detection limit was evaluated as 0.04 to 0.08 mg/m[3]. The method is very sensitive with a relative standard deviation lower than 10%. A major advantage is its remarkable sensitivity, which makes it possible to limit the matrix effect. The analytical method proposed was made use of to determine HANs concentrations in the treated water from the Northern and Central Waterworks of Warsaw. HANs content was found to be insignificant (totalling up to 5 mg/m[3]). Determined were predominantly dichloroacetonitrile, bromochloroacetonitrile and dibromoacetonitrile. Brominated HANs detected in the water intake for the Northern Waterworks occurred at slightly lower concentrations

Soil contamination by PAHsin the vicinity of a heat-generating plant

The investigated object is a coal-fired heat and power generating plant which serves the needs of Radom, a medium-sized municipality in central Poland.Soil and fly-ash samples were collected in the vicinty of the plant and analyzer for the presence of PAHs.PAH concentrations were measured by the HPLC method,according to the USEPA list (16 PAH were determined ). The PAHs identified in the proximity to the plant differed from those determined in the soil samples polluted by car emissions.The soil concentrations of PAHs near the heat and power generating plant were found to be comparatively low,which means that the soil can be used for agricultural needs,as there is no risk of PAH peneration into the food chain

Sorption and desorption of hazardous organic substances in the water/bottom sediment system

Sorpcja zanieczyszczeń organicznych występujących w wodach rzecznych przez osady denne jest procesem powodującym kumulację tych zanieczyszczeń w osadach, natomiast desorpcja tych związków z osadów może spowodować wtórne zanieczyszczenie wód. W pracy przedstawiono wyniki badań mających na celu poznanie dynamiki procesu sorpcji związków organicznych (pestycydy chloroorganiczne, chlorofenole, polichlorowane bifenyle) w układzie woda/osady denne pobrane z Wisły poniżej Krakowa. Badania przeprowadzono w trzech etapach. W pierwszym osad wytrząsano z wodą rzeczną i wodą destylowaną w czasie 12 tyg., oznaczając zawartość badanych związków w wodzie i osadzie, obliczając współczynniki kumulacji analizowanych związków. W drugim etapie, w celu zbadania stabilności badanych związków, wodę rzeczną wytrząsano bez i z dodatkiem HgCl2 przez 7 d. W trzecim etapie do wody rzecznej wraz z osadem dodano roztwory wzorcowe DDT, PCB i chlorofenoli i badano proces sorpcji w ciągu 7 d. Stwierdzono, że proces sorpcji badanych związków na cząstkach osadów zachodził najintensywniej w ciągu kilku pierwszych dób kontaktu osadów z wodą, a następnie stabilizował się. Wykazano, że chlorofenole charakteryzowały się mniejszą trwałością i zdolnością do kumulacji w osadach niż pestycydy chloroorganiczne i PCB. Nie zaobserwowano istotnych zmian zawartości badanych związków w osadzie nawet w przypadku ich wymywania do wody destylowanej, co świadczy o dużej stabilności połączeń (silne oddziaływania hydrofobowe) tych związków z osadem. Można wnioskować, że w przypadku kontaktu osadów z wodą rzeczną w warunkach wymieszania osadów (np. w czasie powodzi) proces przechodzenia tych związków do wody będzie ograniczony.Sorption of organic pollutants in riverine water by bottom sediments accounts for their accumulation inside the bottom sediments while desorption of those pollutants from the bottom sediments can become a contributing factor in the recontamination of riverine water. The aim of the study was to examine the dynamics of the process of organic compound sorption (organochlorine pesticides, chlorophenols, polychlorinated biphenyls), using water-bottom sediments samples collected from the river Vistula downstream of Cracow. The experiments involved three stages. At the first one the bottom sediments samples were shaken with riverine and distilled water for 12 weeks, the contents of particular compounds in the water and in the bottom sediments were determined and their coefficients of accumulation were calculated. At the second stage the river water samples (with and without HgCl2 addition) were shaken for seven days in order to test the stability of the compounds examined. At the third stage the water-bottom sediments samples were added standard solutions of DDT, PCB and chlorophenols, and the sorption process was observed for seven days. The experimental results have revealed the following: the sorption of the compounds on the bottom sediments proceeded at the fastest rate during the first days of contact between bottom sediments and water and then stabilized; the stability of chlorophenols and their propensity to accumulation in the bottom sediments were lower as compared to those of organochlorine pesticides and PCB; no significant changes were observed in the concentrations of the compounds in the bottom sediments even when they were washed out into distilled water. This substantiates the strong hydrophobic interrelations between those substances and the bottom sediments. It can be concluded that if the bottom sediments are in contact with the river water under conditions of bottom sediments mixing (e.g. during flood), the penetration of those hazardous compounds into the water will be limited

Chlorophenols in water environment

Chlorofenole w wodzie oznaczono metodą chromatograficzną z użyciem chromatografu gazowego z detektorem wychwytu elektronów (ECD). Zbadano odzysk chlorofenoli w wodzie destylowanej oraz w wodzie powierzchniowej, który wynosił w zakresie 64-92 %. W próbkach wód powierzchniowych oznaczono następujące chlorofenole: 2-chlorofenol, 2,4-dichlorofenol, 2,4,6-trichlorofenol i pentachlorofenol. Zawartość chlorofenoli oznaczono w wodzie z Wisły na odcinku od Krakowa do Gdańska i w wodach z dwóch małych cieków w okolicy Warszawy (rzeka Jeziorka i Potok Służewiecki). Nie stwierdzono obecności 2-chlorofenolu, natomiast pentachlorofenol występował w prawie wszystkich próbkach wody. W wodzie z Wisły najwyższa była zawartość 2,4-dichlorofenolu - 0,275 mg/m3, natomiast najwyższa zawartość sumy czterech chlorofenoli wyniosła 0,501 mg/m3. Wyższą zawartość chlorofenoli zanotowano w wodach z Jeziorki i Potoku Służewieckiego, w których suma oznaczonych chlorofenoli wyniosła odpowiednio 1,32 mg/m3 i 3,61 mg/m3.Chlorophenols in the aquatic environment were analyzed by gas chromatography with an ECD. Distilled water and surface water samples were compared for chlorophenol recovery which ranged between 64% and 92%. In the surface water samples the presence of 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol was detected. The samples were collected along the Vistula River between Cracow and Gdansk, as well as along two small streams in the proximity of Warsaw (Jeziorka and Potok Sluzewiecki). No 2-chlorophenol was detected in any of the surface water samples while nearly all of them contained pentachlorophenol. The highest concentration of a single chlorophenol in the Vistula amounted to 0.275 mg/m3 (2,4-dichlorophenol), the sum of the four chlorophenols examined being equal to 0.501 mg/m3. Much higher chlorophenol concentrations were determined in the two streams near Warsaw; the sum of the four chlorophenols totalled 1.32 mg/m3 and 3.61 mg/m3 in the Jeziorka and Potok Sluzewiecki, respectively