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Micropollutants and emerging substances pose a serious problem to environmental sustainability and remediation, due to their widespread use and applications in everyday life. This group of chemicals is diverse but with common toxic and harmful properties. Their concentration in the environment is often very low; however, due to their recalcitrant nature, they are persistent in air, water, and soil. From an engineering point of view, the challenge is not straightforward. It is difficult to remove these contaminants from complex mixtures of substances by conventional methods used in wastewater and drinking water treatment. Ozonation and ozone-based AOPs are accepted processes of degradation of resistant substances or at least enhancement of their biodegradability. The aim of this review paper is to present research trends aimed at solving problems in the research and application of ozone-based processes in the removal of micropollutants from wastewater, thus preventing leakage of harmful substances into surface water, soil, and groundwater and facilitating the reuse of wastewater. Priority substances, micropollutants and emerging pollutants, as well as processes and technologies for their transformation and elimination, are briefly specified. Results obtained by the authors in solving research projects that were aimed at eliminating selected micropollutants by ozonation and ozone-based AOPs are also presented. This review focuses on selected alkylphenols, petroleum substances, and organochlorine pesticides.

Funding Information: The authors acknowledge the funding from the European Regional Development Fund and wish to thank the Finnish Foundation of Technology for providing an encouragement grant based on this research work. We would also like to thank the Institute of Biotechnology at the University of Helsinki for the ARG analysis. Funding Information: The authors acknowledge the funding from the European Regional Development Fund and wish to thank the Finnish Foundation of Technology for providing an encouragement grant based on this research work. We would also like to thank the Institute of Biotechnology at the University of Helsinki for the ARG analysis. Publisher Copyright: © 2022 This study collected sludge samples from four different sections of a local wastewater treatment plant in Mikkeli, Finland, for antibiotic resistance genes (ARGs) analysis. Here, we examine the seven representative ARGs in sludge, encoding erythromycin (ermB), tetracycline (tetA, tetC, tetQ, tetW) and sulphonamide (sul1) to check abundance before and after ultrasonication. The class 1 integron (intl1) was also observed as an indicator of antibiotic resistance and horizontal gene transmission. The pre-treatment condition included 10 min of ultrasonication (US) for the sludge sample before freeze-drying. The droplet digital PCR system was used to assess the ARGs from the samples, and it was found that ARGs were not effectively eliminated by pre-treatment. After ultrasonication, tetA, tetC and tetQ did not show any variation but tetW showed 20 copies/ng of lower abundance in digested sludge than raw sludge, and a similar abundance was found in dewatered sludge. For MBR sludge, only ermB showed 1000 copies/ng higher abundance compared to the raw sample and surprisingly it did not show the presence of any other types of ARG. This study provides an overview of the appearance of ARGs in regional municipal sludge for further research reflection.

The minimization of sludge produced by municipal wastewater treatment plants (MWWTPs) is critical as its handling accounts for approximately 50% of the total operating cost. The challenges in predicting dewatering performance can be overcome by optimizing the sludge treatment process, especially conditioning and dewatering. This study aimed to investigate sludge dewaterability at four different MWWTPs, using a gravity drainage test unit and a bench-scale press. The effect of differently treated effluent used as a solvent to mix the flocculation polymers was observed during dewatering. The membrane bioreactor (MBR) treated effluent yielded the highest filtrate volume in the lowest amount of time, with the least polymer flocculant dosage. The Box Behnken Design model fitted the data and proved a relationship between polymer dosage, cake solids concentration, and cake height during the bench-scale press tests. Highlights The type of water used for polymer flocculant dissolution has, to an extent, a considerable impact on the gravity drainage of the sludge.; Increasing polymer flocculant dosing is not directly proportional to the cake height and cake dryness.; Significant correlation between sludge characteristics (e.g. feed solids) and the cake formed.

Waste vegetable oil is generated from different sources, such as domestic, commercial and industrial activities, and it requires proper management. Due to the increase in the generation of waste vegetable oil, concern for its management has intensified. The most common management option for waste vegetable oil is the conversion into biodiesel, which improves the chemical-physical characteristics of raw waste vegetable oil for its use but is characterized by significant energy consumption and environmental impact. Therefore, straight waste vegetable oil as fuel, after mechanical pre-treatments and with suitable operational strategy, is suggested in the available literature. In this work, waste vegetable oil from the separate collection is proposed as a source to fuel a combined heat and power unit producing energy for wastewater and sludge treatment plants, which is high energy-demanding. The operation of the combined heat and power unit is analyzed considering data from an experimental campaign carried out to investigate the performance of internal combustion engines powered by waste vegetable oil. Such experimental data are used to carry out the feasibility analysis of a combined heat and power system for an actual wastewater treatment plant located in the Campania region, southern Italy. The system appears to be economically feasible with a simple payback around 3.44 years, a net present value higher than 19.0 M€ and an interest rate of return of 26.7%. Moreover, it produces 70.0% less equivalent carbon dioxide emissions, with respect to a similar system powered by fossil fuels. Therefore, waste vegetable oil as a locally available and renewable energy source may contribute to realize smart and resilient communities, since it improves securing domestic energy supply and waste valorization.

Sewage sludge handling is becoming a concern in Europe due to its increasing amount and the presence of contaminants, such as heavy metals and pharmaceutical and personal care products (PPCPs). Currently, over 70% of sludge in Europe is treated thermally by incineration or used as fertilizer in agriculture. New thermochemical methods are under development and are expected to be implemented in the near future. This paper considers the life cycle environmental impacts of the following five alternatives for sludge handling, taking into account the presence of heavy metals and PPCPs: i) agricultural application of anaerobically digested sludge; ii) agricultural application of composted sludge; iii) incineration; iv) pyrolysis; and v) wet air oxidation. The results suggest that anaerobic digestion with recovery of nutrients and electricity has the lowest environmental impacts in 11 out of 18 categories considered. For the mean to maximum resource recovery, composting is the worst alternative, followed by pyrolysis with lower recovery rates. Agricultural application of anaerobically digested sludge has the highest freshwater ecotoxicity due to heavy metals, unless their concentration is in the lowest range, as found in some European sewage sludge applied on land. Therefore, stricter control of heavy metals in the sludge is needed for this option to limit freshwater ecotoxicity to the levels comparable with the thermal processes. The results also indicate that PPCPs have a negligible contribution to freshwater ecotoxicity when compared to heavy metals in the anaerobically digested sludge. Since thermal processes are currently drawing attention due to their potential benefits, the findings of this work suggest that their adoption is environmentally beneficial only if high resource recovery rates can be achieved.

NaOH precipitation applied to cheese whey wastewater (CWW) has been investigated in the pH range of 8.5–12.5. Optimum conditions were found at pH 11.0. High reductions of chemical oxygen demand—COD (40%), turbidity—T (91%), total suspended solids—TSS (69%), sulphates (93%), phosphorus (53%), total hardness (40%), calcium (50%), magnesium (27%), chlorides (12%), Kjeldahl nitrogen (23%), etc. were achieved. Treated CWW by the aforementioned process has been used for agricultural irrigation of two tomato cultivars (Roma and Rio Grande) after dilution with fresh water, which was used as control experiment (1.44 dS m−1). Five different irrigation treatments, with salinity level in the range of 1.75–10.02 dS m−1, were implemented with treated wastewater. Treatment did not show a significant effect on the total and marketable yield, production losses and tomato yield with physiological disorder of blossom-end rot. Nevertheless, the cultivar Rio Grande presented an increase up to 21% in the marketable yield, for salinity levels of 1.75–3.22 dS m−1, owing to an increment of the fruit fresh weight. Furthermore, treatment significantly influenced the tomato yield with epidermis deformations by solar exposure, unit fruit fresh weight and tomato number per kilogram. Fruit epidermis deformations due to solar exposition were minimized in about 27–93% when using treated wastewater. Raw sludge generated in the NaOH precipitation presented an average content of organic matter, phosphorus and nitrogen of (g kg−1 on a dry basis) 512, 5.8 and 11.2, respectively. Additionally, this sludge was treated by means of several processes. Centrifugation was quite efficient in the sludge volume reduction. The integrated sequence: aerobic digestion + sedimentation + centrifugation constituted a suitable treatment line, achieving a sludge volume reduction of 80% and simultaneously producing an effluent with organic matter depletion around 40%. Infiltrated water from sand filters was more contaminated organic and inorganically than the effluent obtained in the sequence: aerobic digestion + sedimentation + centrifugation.

Naglim porastom ljudske populacije na Zemlji u zadnjih nekoliko desetljeća te razvojem urbanizacije i industrijalizacije, dolazi do sve većeg onečišćenja vodnih sustava. Jedan od gorućih problema su otpadne vode. Velike količine otpadne vode ispušta se u mora, rijeke ili jezera bez prethodne obrade te ugrožavaju okoliš i ljudsko zdravlje. U diplomskom radu su opisani izvori otpadne vode, procesi obrade otpadnih voda, te zakonska regulativa Republike Hrvatske vezano uz ispuštanje otpadnih voda u okoliš., The rapid growth of the human population on Earth in recent decades, along with urban development and industrialization has resulted in ever increasing pollution of water systems. One of the main problems related to water systems pollution is wastewater discharge. Large quantities of wastewater are discharged into the sea, rivers or lakes without prior treatment, endangering the environment and human health. In this master’s thesis the sources of wastewater, wastewater treatment procedures and national legal regulations on discharge of waste water are described.

The article describes a new bio-inspired method for the Advanced Treatment of Industrial Sludge with a Closed Cycle Drying Process. This process represents an innovative way of treating sludge and other shovelable residues deriving from sludge treatment with centrifuges and other industrial processes taking place in large installations, such as refineries, steel mills, chemical plants, glass processing installations, cosmetics manufacturing facilities, pharmaceutical plants. The process is under development within the research project TAFIPACC funded by Horizon 2020. In particular, the process allows retraining Industrial Sludge into construction materials using the new Closed Cycle Drying Process. The study deals with sludge produced by an industrial treatment plant/industrial discharges and civil waste water in the industrial area of Priolo Gargallo (SR) Esso-Erg-Enichem petrochemical plants and by the municipalities of Priolo Gargallo, and Melilli. The plants produce about 30 cubic meters of sludge per day, disposed of 50% in underground dumps and for the other 50% in hazardous and non hazardous waste recovery plants. The difficulty in the treatment is mainly due to the nature of these muds, as pasty and difficult to mix with additives (cement, limestone, H2O, granulometric mix). The presence of bad odours derives from light and heavy hydrocarbons, aromatics, and organic solvents (benzene, toluene, styrene, xylene, etc), causing some problems to operators and inhabitants living in the areas surrounding the plants.

Recovery of phosphorus from wastewater as calcium phosphate could diminish the need for mining of scarce phosphate rock resources. This study introduces a novel approach to phosphorus recovery by precipitation of calcium phosphate granules in anaerobic treatment of black water. The granules formed in the Upflow Anaerobic Sludge Blanket (UASB) reactor at lab- and demonstration-scale were analyzed for chemical composition and mineralogy by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Electron microprobe (EMP), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and micro X-ray Diffraction (XRD). The granules had a diameter of 1–2 mm, organic content of 33 wt%, and phosphorus content of 11–13 wt%. Three calcium phosphate phases were identified in the granules: hydroxyapatite, calcium phosphate hydrate and carbonated hydroxyapatite. Without any addition of chemicals, 7 gP/person/year can be recovered with the calcium phosphate granules, representing 2% of the incoming phosphorus in the UASB reactor. As the heavy metal content was lower compared to other phosphorus recovery products, phosphate rock and phosphorus fertilizer, the calcium phosphate granules could be considered as a new phosphorus product.

Meat processing wastewater sludge has high organic content but it is very slow to degrade in biological processes. Anaerobic digestion may be a good alternative for this type of sludge when the hydrolysis, known to be the rate-limiting step of biological sludge anaerobic degradation, could be eliminated by disintegration. This investigation deals with disintegration of meat processing wastewater sludge. Microwave (MW) irradiation and combined alkaline pretreatment and MW irradiation were applied to sludge for disintegration purposes. Disintegration performance of the methods was evaluated with disintegration degree based on total and dissolved organic carbon calculations (DD TOC), and the solubilization of volatile solids (S VS) in the pretreated sludge. Optimum conditions were found to be 140°C and 30 min for MW irradiation using response surface methodology (RSM) and pH=13 for combined pretreatment. While DD TOC was observed as 24.6% and 54.9, S VS was determined as 8.54% and 42.5% for MW pretreated and combined pretreated sludge, respectively. The results clearly show that pre-conditioning of sludge with alkaline pretreatment played an important role in enhancing the disintegration efficiency of subsequent MW irradiation. Disintegration methods also affected the anaerobic biodegradability and dewaterability of sludge. An increase of 23.6% in biogas production in MW irradiated sludge was obtained, comparing to the raw sludge at the end of the 35 days of incubation. This increase was observed as 44.5% combined pretreatment application. While MW pretreatment led to a little improvement of the dewatering performance of sludge, in combined pretreatment NaOH deteriorates the sludge dewaterability. © 2013 Copyright Taylor and Francis Group, LLC.

International audience; This article provides data on the contamination of different kinds of sludge (raw, centrifuged, digested, thermally dried sludge and sludge cake) from Paris conurbation by 71 various pollutants including pharmaceutical products (PHPs), hormones, perfluorinated acids (PFAs), linear alkylbenzene sulfonate (LAS), alkylphenols (APs), phthalates (PAEs), polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs).Very high contents of LAS (0.1–10g/kg dry matter - DM) compared to other compounds were found in all types of sludge followed by DEHP (10–100 mg/kg DM) and fluoroquinolones (1–100 mg/kg DM). APs were measured at intermediary contents in Parisian sludge, lying in the 2–20 mg/kg DM range. Finally, hormones, PAHs, PCBs, PAEs, PFAs and the remaining PHPs were all found at contents lower than 1 mg/kg DM.For most compounds (PHPs, PFOS, DEHP, PAHs), no significant differences in the micropollutant contents were found for similar types of sludge from different WWTP in Paris, highlighting the homogeneity of sludge contamination in downstream Paris catchment.The variability of concentration is rather high (coefficient of variation >100%) for several PHPs, PFAs or PCBs while it is moderate (

This report is a synthesis of the technical assistance (TA) and recommendations, carried out by the World Bank water and sanitation program (WSP) since September 2014. To achieve the target of 100 percent improved sanitation, there is a national drive to improve fecal sludge management (FSM). This TA recognizes that to achieve the goals it is necessary to support the development of national FSM policies, regulations, and guidelines, while also improving capacity at the local level by supporting the implementation of improved FSM models in target cities. The objective of the TA was to provide government with tested advice on how to scale up improved septage management nationwide through: (i) improvement of septage management in three cities through the application of new management models (local level); and (ii) assistance to national government in training and capacity building and the formulation of policies and regulations to improve septage management at scale (national level). This report is structured as follows: chapter one is the executive summary; chapter two gives the background to sanitation in Indonesia and to fecal sludge management in particular; chapter three provides an overview of the TA approach; chapter four gives details of the implementation of the TA; chapter five summarizes the lessons learned; and chapter six outlines the recommendations and next steps.

This work aims to evaluate the hydrodynamic properties of the sludge bed of Upflow Anaerobic Sludge Blanket (UASB) reactors based on its settleability and expansion characteristics. The methodologies used for the evaluation of the settleability of aerobic activated sludge, and for the expansibility of a sludge bed of Expanded Granular Sludge Bed reactors and Fluidised Bed Reactors were adapted and applied to the particular characteristics of the sludge of UASB reactors. An easy-to-build experimental set-up was developed to assess the parameters necessary for the equations of settleability and of expansibility. The results obtained from the sludges of seven differently operated reactors show that, for the treatment of low strength wastewater, settleability increased and expansibility decreased at decreased hydraulic retention time, from 6 to 1 h, and/or increased influent concentrations, from 136 to approximately 800 mg chemical oxygen demand/L. The results also show that it is useless to design an UASB reactor with a longer hydraulic retention time to cope with hydraulic shock loads, as a more expansible sludge will develop at such condition.

Reduction and compaction of biological waste sludge from waste water treatment plants (WWTPs) can be achieved with the aquatic worm Lumbriculus variegatus . In our reactor concept for a worm reactor, the worms are immobilised in a carrier material. The size of a worm reactor will therefore mainly be determined by the sludge consumption rate per unit of surface area. This design parameter was determined in sequencing batch experiments using sludge from a municipal WWTP. Long-term experiments using carrier materials with 300 and 350 μm mesh sizes showed surface specific consumption rates of 45 and 58 g TSS/(m 2 d), respectively. Using a 350 μm mesh will therefore result in a 29% smaller reactor compared to using a 300 μm mesh. Large differences in consumption rates were found between different sludge types, although it was not clear what caused these differences. Worm biomass growth and decay rate were determined in sequencing batch experiments. The decay rate of 0.023 d −1 for worms in a carrier material was considerably higher than the decay rate of 0.018 d −1 for free worms. As a result, the net worm biomass growth rate for free worms of 0.026 d −1 was much higher than the 0.009–0.011 d −1 for immobilised worms. Finally, the specific oxygen uptake rate of the worms was determined at 4.9 mg O 2 /(g ww d), which needs to be supplied to the worms by aeration of the water compartment in the worm reactor.

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Sve veći nedostatak vode za piće i sve stroži zakonski zahtjevi za njenu kakvoću, ali i kakvoćom pročišćenih otpadnih voda uvjetuju brži razvoj i primjenu suvremenih tehnologija za obradu voda. Otpadna voda sadrži različita organska i anorganska onečišćenja koje je prije ispuštanja u vodne resurse potrebno svesti na što manju količinu. U posljednjih desetak godina sve značajniju ulogu u obradi otpadnih voda imaju membranski bioreaktori (MBR) koji predstavljaju kombinaciju biološke obrade s aktivnim muljem i membranske filtracije. Iako biološka obrada otpadne vode može biti aerobna ili anaerobna, u praksi se najčešće koristi aerobni postupak obrade aktivnim muljem. Aerobnom obradom otpadne vode nastaju velike količine aktivnog mulja kojeg je potrebno obraditi i zbrinuti na odgovarajući način. Postupci obrade mulja uključuju kondicioniranje, zgušnjavanje, odvodnjavanje, stabilizaciju, kompostiranje te toplinsku obradu, a za cilj imaju smanjenje volumena mulja radi smanjenja troškova daljnje obrade i prijevoza obrađenog mulja te radi sprječavanja neželjenih utjecaja na okoliš pri konačnom odlaganju. U konačnici, obrađeni mulj je moguće odložiti na zemljište te iskoristiti u poljoprivredi, energetici ili građevinskoj industriji, a u skladu sa zakonskom regulativom. A growing shortage of drinking water and increasingly strict legal requirements for it's quality, but also the treated wastewater, cause quicker development and deployment of technologies for wastewater treatment. The wastewater contains various organic and inorganic contaminants, and prior to discharge into streams needs to be processed. In the last decade MBR technology, has increasingly important role in the treatment of waste water, which present combination of biological treatment with activated sludge and membrane filtration. Although the biological treatment of wastewater can be aerobic or anaerobic, in practice, the most commonly used aerobic method for wastewater treatment is activated sludge. Aerobic treatment of wastewater produced a high quantity of active sludge which must be processed and disposed of properly. The procedures include sludge conditioning, thickening, dewatering, stabilization, composting and heat treatment, and their aim is reducing the volume of sludge for costs reduction of further processing and transportation of treated sludge and for the prevention of adverse environmental impact in the final disposal. Finally, the treated sludge can be disposed of on land, used in agriculture, energy and construction industry, in accordance with the legislation.

A finalidade deste trabalho é apresentar uma avaliação da etapa de tratamento de lodos da Estação de Tratamento de Esgotos do Arrudas (Belo Horizonte), em especial os teores de sólidos ao longo do sistema, as principais variáveis de projeto e operação. O processo de tratamento é o de lodos ativados convencional com adensamento por gravidade, digestão anaeróbia e desidratação mecânica. Desde sua entrada em operação até o momento, a estação passou por três fases operacionais quanto ao adensamento dos lodos. A maior concentração média do lodo primário (4,8%) foi atingida no adensador por gravidade quando esse recebia apenas lodo primário. O lodo misto alcançou uma concentração média de 2,7% enquanto o valor esperado de projeto era 5,0%. O lodo secundário excedente, concentrado no adensador por gravidade não ultrapassou 1,8%. A maior concentração média da torta do lodo desidratado (28,3%) foi obtida quando o lodo digerido era proveniente do tratamento primário.This paper aims to evaluate the sludge treatment stage at the Arrudas Wastewater Treatment Plant (Belo Horizonte, Brazil), especially the solids contents throughout the sludge treatment line, as well as the main design and operating variables. The conventional activated sludge plant has a typical solids-line flowsheet: gravity thickening, anaerobic digestion and mechanical dewatering. Three main operational phases have been identified, whose implications in the plant behaviour are analysed in the paper. The highest concentration of primary sludge (mean value of 4.8%) was reached in the gravitational thickening when it was fed with primary sludge only. The mixed sludge concentrated in the gravitational thickening reached only a mean concentration of 2.7%, whereas the expected result was 5.0%. The excess secondary sludge concentrated in the gravitational thickener did not reach 1.8%. The largest concentration of the dewatered sludge cake (means value of 28.3%) was obtained when the digested sludge came from the primary treatment.

Otpadnu vodu potrebno je obraditi prije ispuštanja u vodotokove. Proces obrade otpadnih voda obuhvaća provedbu prethodnih, primarnih, sekundarnih (bioloških) te tercijarnih postupaka. Iako biološka obrada otpadne vode može biti aerobna ili anaerobna, u praksi se češće susreće aerobna tehnologija obrade aktivnim muljem. Aerobnom obradom otpadne vode nastaju velike količine aktivnog mulja kojeg je potrebno zbrinuti na odgovarajući način. Postupci obrade mulja uključuju kondicioniranje, zgušnjavanje, odvodnjavanje, stabilizaciju, kompostiranje te toplinsku obradu. Obrađeni mulj moguće je konačno odložiti na zemljištu (lagune, ozemljavenjem), iskoristiti u poljoprivredi ili upotrijebiti kao sirovinu za dobivanje proizvoda termičkom oksidacijom (bioplin, solidifikacija). Izbor načina konačnog odlaganja mulja odraz je lokalnih, nacionalnih, kulturnih, povjesnih, geografskih, pravnih, političkih i ekonomskih okolnosti. Tako je najšire primjenjivana opcija konačnog odlaganja mulja u EU iskorištavanje mulja u poljoprivredi te odlaganje na odlagalištima, reklamacija i restauracija zemlje te spaljivanje. Obradu mulja treba smatrati sastavnim djelom postupka obrade otadnih voda. U radu su opisani navedeni postupci obrade i konačnog odlaganja mulja s naglaskom na anaerobnoj stabilizaciji. Before discharging into recipient, wastewater must be treated. Wastewater treatment includes previous, primary, secondary (biological) and tertiary treatment. Although biological treatment can be aerobic and anaerobic, the aerobic activated sludge technology is more commonly used. Downside of this technology is that large amounts of active sludge are produced, which should be managed properly. Excess sludge treatment processes include conditioning, concentration, drainage, stabilization, composting and heat treatment. Treated sludge can be disposed on landfills or in lagoons, used in agriculture or in thermal oxidation process for production of new products (solidification). Selection of final sludge disposal mode is reflection of local, national, cultural, historical, geographical, political and economic circumstances. In the EU, the most common disposal mode is exploitation of sludge in agriculture, its disposal on landfills, reclamation and restoration of ground or incineration. Sewage sludge treatment should be considered as a constituent part of wastewater treatment procedure. This paper describes different wastewater sludge treatments and its final disposal, with an accent on the anaerobic stabilization.

This study was carried out to investigate the concentrations and potential sources of the polycyclic aromatic hydrocarbons (PAHs) in sludge of 14 wastewater treatment plants (WWTPs). Sludge samples were collected from 2 municipal WWTPs, 11 industrial WWTPs, and 1 sanitary landfill leachate treatment plant within the city of Bursa, Turkey during the summer of 2008. Ultrasonication was applied for extraction and gas chromatography-mass spectrometry was used to analyze the PAH contents of the samples. Twelve of the 16 EPA-listed PAH compounds were determined. Total PAH concentrations (Sigma(12) PAHs) determined in all of the sludge samples ranged from 1,781 to 19,866 microg/kg dry matter (dm). The sum of 8 of the 11 EU PAHs varied between 1,481 and 17,314 microg/kg dm, and 3 of the samples exceeded the proposed EU limit for land application. One of the automotive industry sludges contained the highest level of PAHs, followed by one of the municipal sludges. The average sum of 5- and 6-ring PAH compounds in all of the sludge samples amounted to almost 65% of the total PAHs. The diagnostic ratios of specific PAHs were calculated to determine the dominant sources for the PAHs in the sludge samples.

Along with economic growth and improved living standards, waste from households, industries, and commercial or service establishments is expected to increase rapidly over the next years. Managing this waste is a hard challenge for the Government of Vietnam because of its substantial cost and lack of awareness and participation of people and businesses. Wastes can be classified according to: their form (wastewater, solid waste); their origin (industrial wastes, agricultural wastes, urban (municipal) wastes); and their hazardous nature (non-hazardous or hazardous).

A finalidade deste trabalho é apresentar uma avaliação da etapa de tratamento de lodos da Estação de Tratamento de Esgotos do Arrudas (Belo Horizonte), em especial os teores de sólidos ao longo do sistema, as principais variáveis de projeto e operação. O processo de tratamento é o de lodos ativados convencional com adensamento por gravidade, digestão anaeróbia e desidratação mecânica. Desde sua entrada em operação até o momento, a estação passou por três fases operacionais quanto ao adensamento dos lodos. A maior concentração média do lodo primário (4,8%) foi atingida no adensador por gravidade quando esse recebia apenas lodo primário. O lodo misto alcançou uma concentração média de 2,7% enquanto o valor esperado de projeto era 5,0%. O lodo secundário excedente, concentrado no adensador por gravidade não ultrapassou 1,8%. A maior concentração média da torta do lodo desidratado (28,3%) foi obtida quando o lodo digerido era proveniente do tratamento primário. This paper aims to evaluate the sludge treatment stage at the Arrudas Wastewater Treatment Plant (Belo Horizonte, Brazil), especially the solids contents throughout the sludge treatment line, as well as the main design and operating variables. The conventional activated sludge plant has a typical solids-line flowsheet: gravity thickening, anaerobic digestion and mechanical dewatering. Three main operational phases have been identified, whose implications in the plant behaviour are analysed in the paper. The highest concentration of primary sludge (mean value of 4.8%) was reached in the gravitational thickening when it was fed with primary sludge only. The mixed sludge concentrated in the gravitational thickening reached only a mean concentration of 2.7%, whereas the expected result was 5.0%. The excess secondary sludge concentrated in the gravitational thickener did not reach 1.8%. The largest concentration of the dewatered sludge cake (means value of 28.3%) was obtained when the digested sludge came from the primary treatment.

The effect of northern European seasonal temperature changes and low temperature on the performance of upflow anaerobic sludge blanket (UASB)-septic tanks treating black water was studied. Three UASB-septic tanks were monitored with different operational parameters and at different temperatures. The results indicated the feasibility of the UASB-septic tank for (pre)treatment of black water at low temperatures with respect to removal of suspended solids and dissolved organic material. Inoculum sludge had little effect on COD(ss) removal, though in the start-up phase some poorly adapted inoculum disintegrated and washed out, thus requiring consideration when designing the process. Removal of COD(dis) was at first negative, but improved as the sludge adapted to low temperature. The UASB-septic tank alone did not comply with Finnish or Dutch treatment requirements and should therefore be considered mainly as a pre-treatment method. However, measuring the requirements as mgCOD l(-1) may not always be the best method, as the volume of the effluent discharged is also an important factor in the final amount of COD entering the receiving water bodies.

The article describes the process of deep aerobic mineralization of activated sludge in municipal wastewater treatment plants using a complex of aerobic heterotrophic and autotrophic microorganisms, including denitrifiers.