Rotating biological contactors : a review on main factors affecting performance

Rotating biological contactors (RBCs) constitute a very unique and superior alternative for biodegradable matter and nitrogen removal on account of their feasibility, simplicity of design and operation, short start-up, low land area requirement, low energy consumption, low operating and maintenance cost and treatment efficiency. The present review of RBCs focus on parameters that affect performance like rotational speed, organic and hydraulic loading rates, retention time, biofilm support media, staging, temperature, influent wastewater characteristics, biofilm characteristics, dissolved oxygen levels, effluent and solids recirculation, stepfeeding and medium submergence. Some RBCs scale-up and design considerations, operational problems and comparison with other wastewater treatment systems are also reported.Fundação para a Ciência e a Tecnologia (FCT

Possibilities of management of waste fly ashes from sewage sludge thermal treatment in the aspect of legal regulations

W ostatnich latach na popularności zyskują termiczne metody unieszkodliwiania osadów ściekowych [14]. Wg prognoz określonych w Krajowym Planie Gospodarki Odpadami 2010 preferowaną metodą postępowania z osadami ściekowymi ma być unieszkodliwianie termiczne. KPGO 2010 zakłada, że ilość osadów przekształcanych termicznie w 2018 r. może wzrosnąć do 60% całkowitej masy osadów. Obecnie jednak łącznie ilość spalarni i obiektów oddawanych w końcowej fazie realizacji w Polsce wynosi osiem [2]. Spodziewać się należy w najbliższych latach kolejnych inwestycji w tym zakresie. W dziedzinie termicznej obróbki osadu ze względów technologicznych można wyróżnić dwa odmienne kierunki. Kierunek pierwszy to instalacja tylko do termicznego przekształcania w postaci spalania. Kierunek drugi natomiast to instalacja składająca się z dwóch elementów: oddzielnie suszenia osadów i następnie ich termicznego przekształcenia. Po procesach termicznych, oprócz emisji gazów do atmosfery, pozostają stałe pozostałości poprocesowe. Jednym z problemów zarysowujących się podczas spalania osadów ściekowych jestryzyko emisji metali ciężkich. Głównie dotyczy to emisji poprzez popioły lotne obecne w gazach spalinowych. Zastosowanie efektywnych urządzeń do ograniczania emisji popiołów, powoduje z jednej strony ograniczenie emisji szkodliwych pierwiastków do atmosfery i dalej na otaczające tereny w wyniku opadu mokrego lub suchego. Przenosi również problem środowiskowy z emisji metali ciężkich do atmosfery na ich obecność w wychwyconym popiele. Powstają zatem pytania: Czy popioły lotne powinny być klasyfikowane jako odpady niebezpieczne? Jakie są możliwości ich zagospodarowania: odzysku i/lub unieszkodliwiania? Celem niniejszej pracy jest analiza możliwości zagospodarowania popiołów lotnych powstałych podczas termicznego unieszkodliwiania osadów ściekowych w aspekcie uwarunkowań prawnych, z uwzględnieniem ich właściwości fizycznych i chemicznych.In recent years, the thermal treatment of sewage sludge technology has become more popular. During thermal treatment of sewage sludge another kind of waste - fly ashes are produced. In paper the trial of his waste classification according to polish law has been conducted. The chemical and physical characteristic of two kinds of ashes has been done. Also, the research of pollutants mobility from ash during extraction into the water has been executed. Basic on waste properties, and also according to law limitation, the possibilities of fly ash management were assessed. Ash has alkaline reaction, contains also relatively high concentration of Ca+2, Mg+2, P2O5 and heavy metals, especially in case of zinc. Executed research indicated low mobility of pollutants during extraction into water. The fly ashes were classified as non hazardous and non inert waste. Basic on the waste management hierarchy, the fly ash from sewage sludge incineration shouldn't lead just to landfilling, but to recovery. Despite of it, because of law limitations, fly ashes from sewage sludge thermal treatment can not to be used directly in the environment, without additional processing. The solution can be: production of fertilizers where one of the components is fly ash; production of light expanded granulatem for reusing in environmental engineering - constructed wetlands for wastewater treatment, construction capture barriers for polluted ground water... And finally, as the worst solution, fly ashes might also be landfilled separately as well mixed withanother waste from group 19 from waste catalogue

Effect of volatile fatty acids (vfas) on the rate of release and uptake of phosphate compounds in an SBR type reactor

Przebadano wpływ lotnych kwasów tłuszczowych (LKT) na szybkość uwalniania i wiązania fosforanów w czasie fazy mieszania i napowietrzania w reaktorze SBR. Określono także sprawności procesów usuwania fosforanów i azotanów (V) w zależności od rodzaju zastosowanego kwasu. Badania przeprowadzono w ramach jednego cyklu pracy SBR (mieszanie - 3 h, napowietrzanie - 4 h i sedymentacja - 1 h) w obecności kwasów: octowego, propionowego, masłowego, izomasłowego, walerianowego, izowalerianowego i kapronowego. Stężenia fosforanów i azotanów na początku cyklu wynosiły odpowiednio 14,1 mg PPO4źdm-3 i 1,22 mg NNO3 dm-3. Stwierdzono, że fosforany uwalniane są z najwyższą szybkością w reaktorach z kwasem octowym (3,85 mg PPO4źdm-3źh-1`) i z najniższą (0,85 mg PPO4źdm-3źh-1) w obecności kwasów izowalerianowego i kapronowego. Również wiązanie fosforanów przebiegało najszybciej w reaktorze z kwasem octowym (5,19 mg PPO4źdm-3źh-1), podczas, gdy najwolniej (2,86 mg PPO4źdm-3źh-1) w obecności kwasu izowalerianowego. Najwyższe szybkości uwalniania i wiązania fosforanów w obecności kwasu octowego były równoznaczne z najefektywniejszym procesem defosfatacji (65,25%). Nie było takiej jednoznacznej zależności w odniesieniu do pozostałych kwasów. Najniższą sprawność usuwania fosforanów, zanotowano w reaktorach dla których zewnętrznym źródłem węgla były kwas izomasłowy (51,06%). Kwas octowy był także najbardziej efektywnym źródłem węgla w odniesieniu do procesu denitryfikacji (57,38%), a najmniej efektywnym był kwas izomasłowy (29,51%). Stwierdzono, że w obecności kwasu octowego zarówno proces defosfatacji jak i proces denitryfikacji przebiegały z najwyższą sprawnością. Najmniej sprzyjającym obu procesom był kwas izomasłowy.The effect of volatile fatty acids (VFAs) on the rate of phosphates release and uptake during stirring and aeration phases in an SBR type reactor was examined in the study. Additional determinations were carried out for the effectiveness of phosphates and nitrates removal as affected by the type of fatty acid applied.The study was conducted within one working cycle of the SBR (stirring - 3 h, aeration - 4 h and sedimentation - 1 h) in the presence of the following fatty acids: acetic, propionic, butyric, isobutyric, valeric, isovaleric and caproic. Initial concentrations of phosphates and nitrates at the beginning of the cycle accounted for: 14.1 mg PPO4/dm3 and 1.22 mg NNO3/dm3, respectively. Analyses showed that phosphates were released with the highest rate in the reactors with acetic acid (3.85 mg PPO4/dm3.h) and with the lowest rate (0.85 mg PPO4/dm3.h) in the presence of isovaleric and caproic fatty acids. Also the uptake of phosphates proceeded with the highest rate in the reactor with acetic acid (5.19 mg PPO4/dm3.h), and with the lowest rate (2.86 mg PPO4/dm3.h) in the presence of isovaleric acid. The highest rates of phosphates release and uptake in the presence of acetic acid were tantamount with the most effective dephosphatation process (65.25%). Such an explicit dependency was not, however, observed in the case of the other fatty acids. The lowest effectiveness of phosphates removal was noted in the reactors in which isobutyric acid was the external source of carbon (51.06%). Acetic acid was also the most effective source of carbon in the denitrification process (57.38%), whereas isobutyric acid turned out to be the least effective in this respect (29.51%).The study demonstrated that in the presence of acetic acid both dephosphatation and denitrification process were proceeding with the highest effectiveness. The least facilitating both these processes appeared to be isobutyric acid

Evaluation of process of biological nitrate and phosphate removal in SBR type reactor with external carbon source

Celem pracy jest określenie wpływu lotnych kwasów tłuszczowych na szybkość uwalniania i wiązania fosforanów w reaktorze SBR oczyszczającym ścieki charakteryzujące się porównywalnymi stężeniami fosforanów i azotanów (V). Celem pracy jest także ustalenie, czy na przebieg i sprawność procesów defosfatacji i denitryfikacji ma wpływ obecność w biomasie osadu czynnego mikroorganizmów zaadaptowanych wcześniej do określonych źródeł węgla. Zakres pracy obejmował określenie: szybkości uwalniania i wiązania fosforanów w obecności kwasów octowego, propionowego, masłowego, walerianowego, izowalerianowego i kapronowego, wpływu rodzaju kwasu na efektywność usuwania fosforanów szybkości procesu denitryfikacji w fazie mieszania i napowietrzania oraz sprawności procesu denitryfikacji w zależności o rodzaju kwasu z grupy LKT.Determinations were made for the effect of volatile fatty acids (VFA) on the rate of release and absorption of phosphates and on the rate of nitrates removal in the stirring and aeration phases in an SBR type reactor. The effectiveness of phosphates and nitrates removal, influenced by the fatty acid applied, was determined as well. The experiment was conducted in SBR type reactors in one working cycle (stirring - 3 h, aeration - 4 h and sedimentation - 1 h) in the presence of acetic, propionic, butyric, isobutyric, valeric, isovaleric and caproic acids. The initial concentrations of phosphates and nitrates were: 13.4 mg PPO4?dm-3 and 15.2 mg NNO3?dm-3, respectively. The study demonstrated that phosphates were released with the highest rate in the reactors containing acetic acid (3.35 mg PPO4?dm-3?h-1), whereas with the lowest rate - in these containing butyric acid (1.25 mg PPO4?dm-3?h-1). Also the process of phosphates absorption proceeded with the highest rate in the reactor with acetic acid (4.19 mg PPO4?dm-3?h-1), and with the lowest rate - in the presence of isobutyric acid (2.13 mg PPO4?dm-3?h-1). In the case of acetic acid, the highest rates of both processes corresponded with the most effective dephosphatation process (50.0%). Such an explicit dependency was not, however, noted in the case of other fatty acids. In the stirring phase, the denitrification process proceeded with the highest rate (3.95 mg NNO3?dm-3?h-1) in the reactor containing caproic acid, and with the lowest rate - in the presence of isobutyric acid (3.42 mg NNO3?dm-3? h-1). During aeration, the rate of nitrates concentration decrease was the highest in the presence of butyric acid (0.91 mg NNO3?dm-3?h-1) and the lowest - in the presence of caproic acid (0.52 mg NNO3?dm-3?h-1). The highest rates of denitrification recorded in both phases in the reactor with caproic acid were not tantamount to the highest effectiveness of nitrates removal. It was the acetic acid that turned out to be the most effective source of carbon in the denitrification process (92.6%) The highest efficiency of both examined processes was observed in the presence of acetic acid. Negligibly lower efficiencies were noted in the reactor with butyric acid. In view of the fact that propionic acid was only slightly less effective both in the denitrification as well as dephosphatation process, it may be speculated that the presence of microorganisms, adapted earlier to specified carbon sources, in the biomass of activated sludge is likely to affect the course and effectiveness of both processes in reactors with an external source of carbon

Application of rotating biological contactor for treatment of wastewaters from fish breeding

Związki azotu negatywnie wpływają na odbiorniki, do których są odprowadzane. Zużywają tlen w procesach utleniania azotu amonowego, co toksycznie wpływa na ryby. Poza tym azot, podobnie jak fosfor, jest czynnikiem powodującym eutrofizację zbiorników wodnych, dlatego redukcja jego zawartości w ściekach jest konieczna. Azot wprowadzany do odbiorników, pochodzi nie tylko ze ścieków komunalnych, ale również z takich gałęzi gospodarki jak przemysł czy rolnictwo. Duże zagrożenie dla wód powierzchniowych stanowi intensywny chów ryb, w szczególności prowadzony w naturalnych akwenach jezior. Z uwagi na ochronę środowiska intensywną hodowlę ryb w zbiornikach naturalnych zastępuje się hodowlą z zamkniętym obiegiem wody, co prowadzi między innymi do zmniejszenia wodochłonności produkcji .This manuscript describes a study conducted in the fractional-technical scale on a rotating electro-biological contactor operating under conditions of electric current flow with a density of: 4.75 mA/m2. Stainless-steel disks with immobilized biomass served as a cathode, whereas an aluminum electrode mounted in the flow tank of the contactor - as an anode. The study was aimed at determining the feasibility of applying electrolytically-aided denitrification in the treatment process of waters from intensive fish breeding. The waters used in the experiment originated from the culture of barramundi fish conducted in a closed system. They were characterized by a high concentration of nitrogen compounds - 79.98 mgN/dm3 and a relatively low concentration of organic compounds expressed as COD - 110.82 mg/dm3, which made the application of the classical denitrification process impossible. The technological design of the study assumed that nitrogen compounds would be subject to reduction during electric current flow. In turn, in the process of water electrolysis, gaseous hydrogen would be produced on the cathode's surface, that would be further utilized as a source of electron donor by autotrophic microorganisms in the denitrification process, owing to the formation of anoxic areas in the deeper layers of the biofilm due to restricted penetration of oxygen. The study resulted in nearly 30% effectiveness of nitrogen compounds removal and over 40% effectiveness of organic compounds removal

The influence of the filtration process on the content of organic compounds in relation to the concentration of nutrients in dairy wastewater

Nowadays, high effective carbon, nitrogen and phosphorus removal based on activated sludge is the most popular method of dairy wastewater treatment. In activated sludge systems efficient nutrient compounds removal is determined by the quantity and quality of easily available forms of organic carbon. For both biological phosphorus removal and biological nitrogen removal to occur, an easily biodegradable carbon source must be present in the treating wastewater. The organic compounds used in the processes of denitrification and enhanced biological phosphorus removal (EBPR) usually are presented in treating wastewater, what is called an internal source of carbon. However, many industrial wastewater, including dairy wastewater, very often do not have sufficient amounts of carbon, in relation to the concentration of nitrate and phosphates, to ensure efficient both denitrification and biological dephosphatation processes. When biological nitrogen and phosphorus removal is limited by the availability of easily biodegradable forms of organic carbon a supplemental carbon source must be add to the wastewater, hence so-called external source of carbon should be applied to provide energy necessary for the nutrient removing bacteria to grow and perform their work. One of the most popular sources of organic carbon is acetic acid, which is one of the best available forms of carbon by denitrifying bacteria and those accumulating polyphosphates (PAO). Apart from acetic acid and acetates use is made of a number of the volatile fatty acids (VFA), including propionic acid, butyric acid, valeric acid, and such substrates as: glucose, methanol or ethanol. Since the use of chemical compounds in the form of technical products (e.g. acetic acid, citric acid) is generally expensive, cost-saving solutions are sought. According to literature data, wastewater with high COD/(N + P) ratio after acidogenic fermentation can be used as an external source of VFA in wastewater with low concentrations of easily available organic compounds treatment. The aim of this study was to determine the influence of the filtration process on the content of organic compounds (measured as COD) in relation to the concentration of nutrients (measured as the sum of TKN and TP) in process dairy wastewater, in terms of the possibility of effective VFA production. It was observed, that filtration process ensures improvement of the COD/(N + P) ratio only in wastewater from the selected sections of dairy production. The best result, if percentage increase of the COD/(N + P) ratio is considered, was obtained for the wastewater from butter production. Densification of wastewater from butter production resulted in 95% increase of the COD/(N + P) ratio without a significant increased nutrient concentration. Filtration process provided the highest COD/(N + P) ratio (219,18 mg O2/(mg N + mg P)) and reduced both nitrogen and phosphorus concentrations in the permeate from the apparatus room. The results obtained suggest, that acidogenic fermentation of wastewater from the apparatus room and butter production with high COD/(N + P) ratio can serve as an external source of VFA in biological wastewater treatment process of wastewater with low concentrations of easily available organic compounds, which ensures effective nitrogen and phosphorus removal

Adsorption of dyes from aqueous solutions on ashes

Celem niniejszej pracy było określenie efektywności adsorpcji barwników anionowych i kationowych z roztworów wodnych na popiołach pochodzących, z dwóch różnych źródeł: ze spalania osadów ściekowych w Grupowej Oczyszczalni Ścieków "Dębogórze" w Gdyni i ze spalania węgla kamiennego w Olsztyńskiej Elektrowni Ciepłowniczej (OZOS). Jako adsorbaty zastosowane zostały barwniki rozpuszczalne w wodzie: z wytworzeniem barwnego kationu - Basic Green 4 (barwnik zasadowy) oraz z wytworzeniem barwnego anionu - Reactive Black 5 (barwnik helaktynowy winylosulfonylowy.This study was conducted with water-soluble dyes used as sorbates: with the formation of color cation - Basic Green 4 (basic dye) and with the formation of color anion - Reactive Black 5 (helactine vinyl sulfone dye). Its objective was to investigate possibilities of dyes adsorption from aqueous solutions on ashes. The scope of the study included a comparison of adsorption effective-ness of two dyes originating from the textile industry: Reactive Black 5 (RB5) and Basic Green 4 (BG4) by fly ashes of two different origins: from coal combustion at the Olsztyn Thermal Power Station (OZOS), from combustion of sewage sludge originating from Group Wastewater Treatment Plant "Dębogórze" in Gdynia. Results achieved in the study demonstrated that the effectiveness of the adsorption process was determined by the type of dye and adsorbent as well as by pH value of the aqueous solution. In the case of the anionic dye RB 5, the increase in pH was accompanied by diminishing adsorption effectiveness, whereas an opposite tendency was observed in the case of the cationic dye BG4 when the increase in pH value resulted in enhanced dye removal. The fly ashes applied in the research, both from the Thermal Power Station OZOS and from combustion of activated sludge, were characterized by a high effectiveness of cationic dye removal. In the case of the cationic dye BG 4, the highest adsorption capacity (b) accounting for 500.5 mg/g was achieved on fly ashes from the Thermal Power Station at pH = 9.0. In turn, the effectiveness of anionic dye RB 5 removal on both sorbents was at a similar, considerably lower level (0.6÷4%). In the case of this dye, the highest adsorption capacity (b) reaching 6 mg/g d.m. was achieved on ashes from the sludge at pH 3.0, whereas the lowest one ? 0.1 mg/g d.m. - at pH 9.0 on fly ashes from the Thermal Power Station

Effect of electric current flow on nitrification and denitrification processes in a four-stage rotating biological contactor

Konieczność zwiększania skuteczności procesów usuwania związków azotu ze ścieków prowadzi do opracowywania nowych metod biologicznych lub poprawy efektywności już stosowanych rozwiązań technicznych. Proces ten dotyczy także biologicznych złóż obrotowych, które w ostatnich latach zaczęły odgrywać znaczącą rolę w małych i średnich oczyszczalniach do oczyszczania ścieków przemysłowych i bytowo-gospodarczych. Kierunek zmian dotyczy m.in.: wprowadzania nowych konstrukcji wypełnień, stosowania różnych napędów wprawiających materiał wypełniający w ruch obrotowy, wydłużania czasu retencji ścieków w komorze, różnych technik dostarczania ścieków do reaktora, prowadzenia biodegradacji zanieczyszczeń z procesami elektrochemicznymi oraz współpracy złóż biologicznych z metodą osadu czynnego. W niniejszej pracy przedstawione zostały badania prowadzone w skali ułamkowo-technicznej na elektro-biologicznym złożu tarczowym pracującym w układzie czterostopniowym w warunkach przepływu prądu elektrycznego o gęstości: 4,2 mAm-2. Katodą były tarcze ze stali nierdzewnej z unieruchomioną błoną biologiczną, natomiast anodą - elektroda aluminiowa zamontowana w zbiorniku przepływowym złoża. Równolegle prowadzone były badania na czterostopniowym złożu tarczowym w warunkach konwencjonalnych (gdy nie przepływał prąd elektryczny), w którym czwarty stopień, w celu prowadzenia procesu denitryfikacji, był hermetycznie przykryty. Badania nie wykazały wpływu przepływu prądu elektrycznego na sprawność utleniania związków azotu. Na elektro-biologicznym złożu tarczowym uzyskano ponad 97% sprawność nitryfikacji i niewiele niższą w warunkach konwencjonalnych - około 96%. Stwierdzono natomiast, na podstawie przeprowadzonej analizy wariancji, przy użyciu testu nieparametrycznego Friedmana, wpływ przepływu prądu elektrycznego na efektywność denitryfikacji. W warunkach przepływu prądu elektrycznego obserwowano ponad 41% sprawność procesu redukcji związków azotu utlenionych w procesie nitryfikacji. W warunkach konwencjonalnych obserwowano 35% efektywność denitry-fikacji.The necessity of enhancing the effectiveness of nitrogen compounds removal from wastewaters leads to the elaboration of novel biological methods or to the improvement of effectiveness of the already exploited technical solutions. This refers also to rotating biological contactors (RBCs) which in recent years have begun to play a key role in small- and medium-size treatment plants for the treatment of industrial and domestic sewages. Changes proceeding in this respect involve: introduction of new constructions of fillings, application of different drivers putting the filling material into rotary motion, extension of the time of sewages retention in the reactor, application of different technologies of wastewater discharge to the reactor, electrochemically-aided biodegradation of contaminants, and cooperation of biofilters with the method of activated sludge. This work presents a study conducted in a fractional-technical scale on a rotating electro-biological contactor operating in a four-stage system under conditions of the flow of electric current with a density of 4.2 mAm-2. In the RBC unit, stainless steel disks with immobilized biofilm served as a cathode, whereas an aluminum electrode fixed in the flow tank of the contactor - as an anode. Parallel experiment was conducted on the four-stage RBC under conventional conditions (without the flow of electric current), in which the fourth stage was hermetically closed to enable the denitri-fication process.The study did not demonstrate the electric current flow to affect the effectiveness of nitrogen compounds oxidation. The effectiveness of denitrification achieved on the rotating electro-biological contractor accounted for 97%, whereas that obtained under conventional conditions was only negligibly lower and reached ca. 96%. In turn, the analysis of variance conducted with the Friedman's non-parametric test demonstrated the effectiveness of denitrification to be affected by electric current flow. Under conditions of electric current flow, the effectiveness of the reduction of nitrogen compounds oxidised during nitrification reached over 41%, as compared to 34% achieved under conventional conditions

Effect of Electrochemical Process on the Concentration of Total Nitrogen and Orthophosphates in the Outflow from the Reactor with Immobilized Biofilm

Municipal and industrial wastewaters discharged to water reservoirs should be characterized by a low load of nutrients. Nitrogen and phosphorus are responsible for eutrophication, is therefore necessary to find the effective solutions for their removal. The experiment has been carried in order to determine the impact of the electric current density on the course of simultaneous electrocoagulation and hydrogenotrophic denitrification in the rotating electro-biological contactor (REBC).The study was conducted in the laboratory scale, parallely in three anaerobic reactors, in conditions of the flow electric current. In the REBC unit, rotating disks made of stainless steel with immobilized biofilm were the cathode. Hydrogen donor produced on the surface of cathode, in water electrolysis process, was used by denitrifying bacteria for nitrates reduction. As the anode an aluminum electrode mounted in the reactors was used. As a result of the anode electrolytic dissolution releasing Al3+ ions combined with the hydroxyl ions emitted on the cathode, formed metal hydroxides, which functioned as a coagulant in the binding of phosphate ions. In crude wastewaters inflowing to the bioreactors the concentration of orthophosphates was 8.1 mgPO4×dm-3 and total nitrogen 81.36 mg Nog×dm-3 and the concentration of organic compounds was equal 40.52 mg O2×dm-3 . The study showed that regardless the operating parameter of the electrolysis process, effluent concentration of orthophosphate below 1 mg PO4×dm-3 was obtained. However, the lowest concentration were observed at a density 0.05 mA×cm-2 . The efficiency of 97.27% corresponded to the phosphate concentration equal 0.22 mg PO4×dm-3. The increase of electric current density resulted in a higher concentration of orthophosphate in the effluent from the reactors, because of more intensive dissolution of aluminum hydroxide with the increase of wastewater alkalinity and a limited amount of secreted Al3+ ions, as a result of aluminum oxide accumulation on the anode surface. In the same time, electrolytically-aided denitrification process affected the reducing concentration of total nitrogen in the wastewaters with the increase of electric current density, as a result of intensive use a hydrogen donor by denitrifying bacteria. The lowest concentration of total nitrogen in the treated wastewaters was achieved at the highest current density 0.1 mA cm-2 – 16.15 mgNog dm-3 , which corresponded to 80.15% effectiveness. The research has shown that bio-electrochemical reactor may be an alternative solution for reactors with suspended biomass designed for nutrients removal

Characteristics of wastewater from animal rendering plant

In this study, wastewater originating from a post-slaughter waste management plant, the main activity of which is the recovery of other than hazardous wastes of animal origin and wastes from the agri-food processing, were analyzed. The main substrates processed in the installation include post-slaughter wastes and wastes from the agri-food processing, like e.g.: waste animal tissue, raw materials and products unsuitable for consumption and processing originating from the food, dairy, bakery and confectionery industries, sludge from the onsite wastewater treatment plant, unusable dietary fats, cooking oils and fats, and biodegradable kitchen waste. The above-mentioned wastes are recovered and processed into meat-bone meal, blood meal, feather meal as well as technical fat. The wastewater was characterized by a high concentration of organic matter (COD from 20 345 to 66 260 mg O2/dm3), total suspended solids (from 1068 to 4336 mg/dm3), and fats (from 1186 to 2244 mg/dm3). Phosphorus concentration in raw wastewater ranged from 75 to 230 mg P/dm3, that of total nitrogen from 496 to 910 mg N/dm3, and that of ammonia nitrogen from 450 to 846 mg N/dm3. The process line of the onsite wastewater treatment plant included: rotary screen, floatation-flocculation station (agents and procedures aiding the process: PIX coagulant, pH adjustment with soda lye, polyelectrolyte), aerobic bioreactor, and ultrafiltration station. The excess sludge from the bioreactor is dewatered on a filtration press and collected by an external company as a waste product. Removal effectiveness reached 99.7% for organic matter, 98.5% for total phosphorus, 95.2% for total nitrogen, 98.5% for ammonia nitrogen, and 98.9% for suspended solids. The total effectiveness of the first two stages of the treatment process (screening on rotary screens and wastewater treatment via floatation and flocculation) exceeded 50% in the case of most of the contaminants (except for total nitrogen with effectiveness accounting for 46%). The highest total effectiveness of the first two stages of the treatment process, reaching over 90%, was noted in the case of fats. Concentrations of contaminants in the treated wastewater did not exceed the permissible values, stipulated in the integrated permit.Celem pracy była charakterystyka ścieków pochodzących z zakładu utylizacji odpadów poubojowych oraz ścieków po kolejnych etapach oczyszczania. W skład ciągu technologicznego oczyszczalni wchodzi sito obrotowe, stacja flotacyjno-flokulacyjna, tlenowy reaktor biologiczny i stacja ultrafiltracji. Badania wykonano w latach 2015-2016. Próbki pobrano siedmiokrotnie - trzy w roku 2015 i cztery w 2016 (maj, czerwiec). Ścieki charakteryzowały się wysokim stężeniem związków organicznych wyrażonych ChZT (od 20 345 do 66 260 mg O2/dm3), zawiesin ogólnych (od 1068 do 4336 mg/dm3), tłuszczów (od 1186 do 2244 mg/dm3). Równocześnie stężenie fosforu ogólnego w ściekach surowych wynosiło od 75 do 230 mg P/dm3, azotu ogólnego od 496 do 910 mg N/dm3, a stężenie azotu amonowego od 450 do 846 mg N/dm3. Związki organiczne usuwane były ze sprawnością 99,7%, fosfor ogólny - 98,5%, azot ogólny - 95,2%, azot amonowy - 98,5% i zawiesiny - 98,9%. Sumaryczna efektywność w dwóch pierwszych etapach oczyszczania na sitach obrotowych oraz w procesie flotacji i flokulacji w większości przypadków była wyższa od 50% (wyjątek stanowił azot ogólny). Stężenia wskaźników zanieczyszczeń w ściekach oczyszczonych nie przekraczały wartości dopuszczalnych, określonych w pozwoleniu zintegrowanym