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PL
Wody osadowe odpływające podczas mechanicznego odwadniania osadów ściekowych charakteryzują się najczęściej wysoką zawartością związków biogennych, dlatego podjęto badania, których celem było określenie jakości wód osadowych uzyskiwanych podczas odwadniania osadów kondycjonowanych siarczanem żelaza(III), siarczanem glinu lub tlenkiem wapnia. Każdy z przebadanych związków miał inny wpływ na jakość odcieków uzależniony głównie od zastosowanej dawki, jak i właściwości osadów. Siarczan żelaza i siarczan glinu zatrzymywał związki fosforu tylko w określonym zakresie pH. Wprowadzenie do osadów siarczanu żelaza w ilości powyżej 15,5% s.m. oraz powyżej 5,0% s.m. w przypadku siarczanu glinu skutkowało znacznym obniżeniem odczynu i wzrostem zawartości ortofosforanów w wodach osadowych. Zastosowany do kondycjonowania osadów tlenek wapnia wykazywał się skutecznością w zatrzymywaniu ortofosforanów w całym przebadanym zakresie dawek. Jednocześnie odcieki odpływające podczas stosowania tego związku charakteryzowały się wzrastającą wartością pH i ChZT.
EN
During mechanical sludge dewatering the filtrate is produced. Filtrate is usually characterized by a high content of nutrients. In order to determine the possibility of simultaneous process of dewatering and retention of phosphorus compounds in the sludge, the studies have been carried out using organic and inorganic coagulant in the process of conditioning. These treatments have an impact both on the efficiency of the dewatering process and the characteristics of water flowing from the sludge. The studies was conducted in the laboratory using the sludge from a fish farm applying an industrial the fattening of the rainbow trout. For the conditioning of the sludge inorganic metal salts were used: iron sulfate, aluminum sulfate and calcium oxide. The sludge used in the studies characterized a high content of phosphorus, which had an impact on the concentration of these components in the water from the sludge. The use of coagulants in the process of conditioning influenced both positively and negatively on the quality of the effluent leachate. It was dependent on the type of conditioning agent, the size of the dose and the sludge characteristics. High doses of ferrous sulfate and aluminum sulfate resulted in a reduction to a value of pH of the sludge at which phosphorus compounds did not precipitated. In these conditions an increase of the contents of these compounds in the sludge water was observed. With the increase of the dose of the calcium oxide used for the conditioning of the sludge the efficiency of the phosphorus compounds removal was increased. This water from the sludge also characterized by a high pH value, which contributed to their hygenization.
EN
The main objective of this paper was to compare efficiency of electrocoagulation and metal dissolution methods in orthophosphate removal from synthetic wastewater at 7.0 and 8.0 pH. The research was conducted with usage of steel electrodes with 1414 cm2 contact surface, which were corroding and releasing iron ions responsible for orthophosphate precipitation. The electrocoagulation process with alkaline wastewater (8.0 pH) was additionally using a direct electrical current with intensity of 0.1 A and voltage of 1.5 V. Changes of the pH value, orthophosphate and iron ions content were also measured. Obtained results show, that wastewater treatment from orthophosphate with electrocoagulation takes place much faster than with metal dissolution method. Complete orthophosphate removal (starting concentration was 10.5 mg P/dm3) with electrocoagulation process occurred after 415 minutes of research, when metal dissolution method obtained the same effect after 1445 minutes. In the wastewater with starting 7.0 pH and with electrocoagulation, the total dephosphatation occurred after 1440 min, but the metal dissolution method after this time ensure only 37% reduction in the orthophosphate concentration. The pH value of treated wastewater increased during the every study. The most noticeable increase was while using electrocoagulation process, which attained 11.1 pH (wastewater with starting 8.0 pH) and 10.8 pH (wastewater with starting 7.0 pH) after 1440 minutes. Applying the metal dissolution method increase in pH was lower, was respectively 8.8 pH and 8.6 pH. Concentration of iron ions concentration also increased in treated wastewater. In the wastewater with starting 8.0 pH, from 0.00 mg Fe/dm3 to 0.16 mg Fe/dm3 with metal dissolution method and 0.00 mg Fe/dm3 to 0.46 mg Fe/dm3 with electrocoagulation. In the wastewater with starting 7.0 pH, the maximum observed total iron concentration was 0.04 mg Fe/dm3. Electrocoagulation method turned out to be more effective in orthophosphate removal from wastewater than metal dissolution method, which occurred in shorter time needed for dephosphatation. However it requires a more consumables funding related to the use of energy and electrodes wearing faster.
EN
Impurities which are produced in the process of intensive fish breeding usually accumulate at the bottom of ponds and pools where the fattening is conducted, resulting in sludge rich in organic matter and biogenic elements. The sludge, consisting mainly of fish faeces and the fodder uneaten by the fish, accumulates in special zones intended for this purpose. As the experiment shows, the ability of the sludge to yield water is very poor and the sludge should be classed as poorly dewatering. Therefore, before it was dewatered in a laboratory the sludge was conditioned with inorganic compounds and cationic polyelectrolytes in order to facilitate the process. The inorganic compounds used for conditioning were: technical grade iron (III) sulphate – trade name “PIX 113”, aluminum sulphate and calcium oxide. The sludge was dewatered in a reduced pressure device, equipped with a Büchner funnel, which enables the determination of the specific resistance. The collected sludge contained variable amounts of dry matter and organic matter. The study presents the results of determination of the specific resistance, final dewatering of sludge and its content of organic matter, depending on the type and amount of the conditioning agent applied. The results also allowed the determination of the doses which optimally facilitate the dewatering process and reduce the degree of sludge hydration. The process effectiveness was found to be dependent mainly on organic matter content in sludge. It was also found that the specific resistance was most reduced by cationic polyelectrolytes, while the final hydration was the lowest when calcium oxide was used. The determined optimal doses depended on organic matter content and ranged: for iron sulphate from 0.7 to 15% (d.m.), for aluminum sulphate from 0.6 to 15% (d.m.), for calcium oxide from 7 to 30% (d.m.), for cationic polyelectrolytes from 0.064 to 0.19% (d.m.) of sludge. No statistically significant differences were found in dewatering effectiveness between iron sulphate and aluminium sulphate.
PL
Reakcja wytrącania struwitu może zachodzić w sposób niekontrolowany i powodować zakłócenia w pracy oczyszczalni ścieków lub stanowić podstawę usuwania azotu amonowego i ortofosforanów ze ścieków. Niekontrolowane wytrącanie struwitu najczęściej jest następstwem zmniejszenia zawartości wolnego dwutlenku węgla, spadku temperatury osadów lub zmiany innego czynnika zaburzającego stan równowagi chemicznej w układzie. Efekt taki można również uzyskać, np. napowietrzając osady. Ponieważ stwierdzony w surowych osadach ściekowych stosunek azotu amonowego do ortofosforanów jest bardzo niekorzystny, ilość wytrącającego się struwitu (a jednocześnie azotu amonowego) jest bardzo mała, co ze względów eksploatacyjnych oczyszczalni ścieków może się wydawać nawet korzystne. Dopiero wprowadzanie do osadów ściekowych dodatkowych ilości ortofosforanów umożliwiło zwiększenie ilości usuwanego azotu amonowego. Przy uzyskanym w ten sposób stosunku stechiometrycznym Mg:N:P = 1,0:1,25:0,95 i przy początkowym pH = 9,41 maksymalnie usunięto 70,32% azotu amonowego i 98,4% ortofosforanów.
EN
Struvite precipitation may occur spontaneously and disturb the functioning of waste-water treatment plants or it may result in the removal of ammonium nitrogen or orthophosphates from sewage. This uncontrolled precipitation of struvite is most frequently the result of a reduction in the content of free carbon dioxide and the sludge temperature or a change in another factor disturbing the chemical equilibrium in the system. Since the ammonium nitrogen-toorthophosphate ratio found in the raw sludge waters is very unfavourable, the amount of precipitating struvite (including ammonium nitrogen) is very small. This is quite desirable in respect to exploitation of a waste-water treatment plant. Only after the introduction of additional amounts of orthophosphates into waste sludge was the removal of increased amounts of ammonium nitrogen possible. At a stoichiometric ratio of Mg:N:P = 1,0:1,25:0,95, and an initial pH = 9,41, a maximum of 70,32% of ammonium nitrogen and 98,4% of orthophosphates were removed.
PL
Dotychczas wykorzystanie procesów elektrolizy lub elektrokoagulacji rozpatrywano najczęściej pod kątem możliwości oczyszczania wody lub ścieków. W niniejszej pracy zaprezentowano możliwości zastosowania tych metod w przeróbce osadów ściekowych do oczyszczania wód osadowych. Przedstawione rezultaty umożliwiają wyciągnięcie kilku podstawowych wniosków.1. Elektroliza z wykorzystaniem elektrod żelaznych prowadzona w osadach ściekowych wpływa na zawartość azotu amonowego i ortofosforanów w odciekach uzyskiwanych podczas odwadniania.2. Efektywność elektrokoagulacji ortofosforanów jest bardzo wysoka w układzie z elektrodami stalowymi i wzrasta wraz z powierzchnią zastosowanych elektrod. 3. Wzrost powierzchni elektrod tylko nieznacznie wpływała na efek-tywność usuwania azotu amonowego z osadów.
EN
The use of electrolysis or electrocoagulation has been usually contemplated with respect to purification of water and wastewater. This study presents the possibility of applying the methods in sludge processing to purify sludge waters. The effect of electrolysis was determined on sludge temperature and pH change and on the concentration of biogenic compounds in effluents produced during their dehydration. The sludge used in the study was obtained from the municipal wastewater treatment plants in Olsztyn and Olsztynek. They con-tained 47 and 173 mg PO4/dm3 or 150 and 580 mg N-NH4/dm3 depending on the experimental series. Electrolysis was conducted at the voltage of 36 V with iron rods. Direct current was generated by a rectifier. The area of one electrode was changed during the experiment from 5.2 to 67 cm2. The area and shape of both electrodes were identical. The duration of electrolysis was 30 minutes. The maximum effectiveness of orthophosphate removal from sludge containing 47 mg PO4/dm3 was 95%. When electrolysis was applied to purify sludge with a higher initial concentration of orthophosphates, the highest effectiveness achieved after 30 minutes was equal to 81.4%. The effectiveness of ammonium nitrogen removal ranged from 8.5 to 13.2%. Such low effectiveness may have been caused by the short time of the process or caused by the rapid growth of the sludge temperature. The removal rate of N-NH4+ depended mainly on the initial concentration and - to a minor extent - on the area of electrodes used, which implies that both temperature and pH may have contributed to the removal of the nitrogen species. Changes of pH and temperature depended mainly on the type of sludge used. The temperature achieved with the largest electrode area ranged from 31.9 to 57.0°C. The pH increased proportionally and reached maximum values of 7.6 and 7.8 after 30 minutes of electrolysis (with an area of 67.0 cm2).
EN
Because the application of pressure in electro-dewatering of wastewater sludge (and consequent compression) affects processes of electroosmosis and electrophoresis, the study aimed at determining the effect of vacuum and constant electric field on the specific resistance of sludge and quality of filtrate. It was found that both the current intensity and direction affects the biogen content in sludge dewatering filtrate. An increase in the intensity of the current applied to the filtering barrier was accompanied by an increase in the effectiveness of the removal of ammonium nitrogen (filtering barrier as an anode) and orthophosphates (filtering barrier as a cathode). A constant electric field was shown to considerably affect the specific resistance of sludge filtration.
PL
Powszechnie stosowana w gospodarstwach pstrągowych metody usuwania zanieczyszczeń stałych polega na usuwaniu zawiesiny poprzez jej sedymentację w wydzielonych strefach basenów do tuczu ryb. W wodach odpływających z basenów oraz ze stawu osadowego do odbiornika stwierdzono statystycznie istotny wzrost zawartości związków azotu i fosforu. Średnie ich stężenie było większe od ilości zawartej w wodzie dopływającej o 0,37 mg N/dm3 i o 0,121 mg P/dm3. BZT5 w odpływie ze stawu osadowego wzrastało średnio o 2,89 mg O2/dm3, a stężenie azotu amonowego o 0,404 mg N/dm3. Uzyskane wyniki pozwoliły stwierdzić, że prowadzony w gospodarstwie sposób usuwania zanieczyszczeń stałych poprzez ich gromadzenie w stawie osadowym zmniejsza ilość odprowadzanych do odbiornika zanieczyszczeń tylko o około 10-15% ilości wprowadzonej do wody z paszą. Największy wpływ ma na to długi okres magazynowania osadów w stawie osadowym, co wpływa na uwalnianie do przepływającej wody azotu i fosforu ogólnego wcześniej zatrzymanych razem z zawiesiną.
EN
Methods of the particles pollutants removal, commonly used in trout farms, lay in the fact of suspension removal through the sedimentation in selected zones of the fish-fattening basins. In the effluent from the basins and from sediment pond to the receiving water the increase in nitrogen and phosphorus compounds concentrations was observed. The average values of the contents in the effluent were higher that in the influent by 0,37 mg N/dm3 and 0,121 mg P/dm3. There was the increase in BOD5 concentration in the effluent from sediment pond by 2,89 mg O2/dm3, as for ammonium by 0,404 mg N/dm3. Obtained results let to conclude that in described trout farm, method of particles pollutants removal through it accumulation in the sediment pond caused the decrease in pollutants concentrations by 10 to 15% of the contents supplied to water with feeding fodder. The highest impact on it has long period of sediment accumulation in sediment pond what influence on nitrogen and total phosphorus releasing (earlier accumulated in the suspension) to the effluent.
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