D. Brdjanovic - Academia.edu (original) (raw)

Papers by D. Brdjanovic

Water Intelligence Online, 2016

Water Intelligence Online, 2015

Over the past twenty years, the knowledge and understanding of wastewater treatment have advanced... more Over the past twenty years, the knowledge and understanding of wastewater treatment have advanced extensively and moved away from empirically-based approaches to a first principles approach embracing chemistry, microbiology, physical and bioprocess engineering, and ...

Journal of Hydroinformatics, 2015

Water Research, 2015

The anaerobic acetate (HAc) uptake stoichiometry of phosphorus-accumulating organisms (PAO) in en... more The anaerobic acetate (HAc) uptake stoichiometry of phosphorus-accumulating organisms (PAO) in enhanced biological phosphorus removal (EBPR) systems has been an extensive subject of study due to the highly variable reported stoichiometric values (e.g. anaerobic P-release/HAc-uptake ratios ranging from 0.01 up to 0.93 P-mol/C-mol). Often, such differences have been explained by the different applied operating conditions (e.g. pH) or occurrence of glycogen-accumulating organisms (GAO). The present study investigated the ability of biomass highly enriched with specific PAO clades ('Candidatus Accumulibacter phosphatis' Clade I and II, hereafter PAO I and PAO II) to adopt a GAO metabolism. Based on long-term experiments, when Poly-P is not stoichiometrically limiting for the anaerobic VFA uptake, PAO I performed the typical PAO metabolism (with a P/HAc ratio of 0.64 P-mol/C-mol); whereas PAO II performed a mixed PAO-GAO metabolism (showing a P/HAc ratio of 0.22 P-mol/C-mol). In short-term batch tests, both PAO I and II gradually shifted their metabolism to a GAO metabolism when the Poly-P content decreased, but the HAc-uptake rate of PAO I was 4 times lower than that of PAO II, indicating that PAO II has a strong competitive advantage over PAO I when Poly-P is stoichiometrically limiting the VFA uptake. Thus, metabolic flexibility of PAO clades as well as their intrinsic differences are additional factors leading to the controversial anaerobic stoichiometry and kinetic rates observed in previous studies. From a practical perspective, the dominant type of PAO prevailing in full-scale EBPR systems may affect the P-release processes for biological or combined biological and chemical P-removal and recovery and consequently the process performance. .eg (S. Saad), b.a.abbas@tudelft.nl (B. Abbas), c.lopezvazquez@unesco-ihe.org (C.M. Lopez-Vazquez), t.hooijmans@unesco-ihe.org (C.M. Hooijmans), m.c.m. vanloosdrecht@tudelft.nl (M.C.M. van Loosdrecht), d.brdjanovic@unesco-ihe.org (D. Brdjanovic).

Proceedings of the Water Environment Federation, 2013

World journal of microbiology & biotechnology, 2015

In the sewage or wastewater treatment plant, biological sulphate reduction can occur spontaneousl... more In the sewage or wastewater treatment plant, biological sulphate reduction can occur spontaneously or be applied beneficially for its treatment. The results of this study can be applied to control SRB in the sewage and WWTP. Therefore, population diversity analyses of SRB for nine activated sludge wastewater treatment plants (WWTP) in the Netherlands and the effect of long-term (months) oxygen exposures on the SRB activity were carried out. T-RFLP and clone sequencing analyses of winter and summer samples revealed that (1) all WWTP have a similar SRB population, (2) there is no seasonal impact (10-20 °C) on the SRB population present in the WWTP and (3) Desulfobacter postgatei, Desulfovibrio desulfuricans and Desulfovibrio intestinalis were the most common and dominant SRB species observed in these samples, and origin from the sewage. Short term activity tests demonstrated that SRB were not active in the aerobic WWTP, but while flushed with N2-gas SRB became slightly active after 3 ...

Water Science and Technology, 1999

Science of The Total Environment, 2015

We developed a DSS to select and plan for faecal sludge management in emergencies • The DSS is us... more We developed a DSS to select and plan for faecal sludge management in emergencies • The DSS is useful for planners to make decisions in relatively short time • The DSS is designed as a computer-based program that can easily be modified • The DSSis user-friendly and can be operated offline • Preliminary validation of the DSS shows that it can provide realistic results a b s t r a c t Proper provision of sanitation in emergencies is considered a life-saving intervention. Without access to sanitation, refugees at emergency camps are at a high risk of contracting diseases. Even the most knowledgeable relief agencies have experienced difficulties providing sanitation alternatives in such challenging scenarios. This study developed a computer-based decision support system (DSS) to plan a sanitation response in emergencies. The sanitation alternatives suggested by the DSS are based on a sanitation chain concept that considers different steps in the faecal sludge management, from the toilet or latrine to the safe disposal of faecal matters. The DSS first screens individual sanitation technologies using the user's given input. Remaining sanitation options are then built into a feasible sanitation chain. Subsequently, each technology in the chain is evaluated on a scoring system. Different sanitation chains can later be ranked based on the total evaluation scores. The DSS addresses several deficiencies encountered in the provision of sanitation in emergencies including: the application of standard practices and intuition, the omission of site specific conditions, the limited knowledge exhibited by emergency planners, and the provision of sanitation focused exclusively on the collection step (i.e., just the provision of toilets).

Applied Microbiology and Biotechnology, 2014

The use of saline water as secondary quality water in urban environments for sanitation is a prom... more The use of saline water as secondary quality water in urban environments for sanitation is a promising alternative towards mitigating fresh water scarcity. However, this alternative will increase the salinity in the wastewater generated that may affect the biological wastewater treatment processes, such as biological phosphorus removal. In addition to the production of saline wastewater by the direct use of saline water in urban environments, saline wastewater is also generated by some industries. Intrusion of saline water into the sewers is another source of salinity entering the wastewater treatment plant. In this study, the short-term effects of salinity on the anaerobic metabolism of phosphate-accumulating organisms (PAO) and glycogen-accumulating organisms (GAO) were investigated to assess the impact of salinity on enhanced biological phosphorus removal. Hereto, PAO and GAO cultures enriched at a relatively low salinity level (0.02 % W/V) were exposed to salinity concentrations of up to 6 % (as NaCl) in anaerobic batch tests. It was demonstrated that both PAO and GAO are affected by higher salinity levels, with PAO being the more sensitive organisms to the increasing salinity. The maximum acetate uptake rate of PAO decreased by 71 % when the salinity increased from 0 to 1 %, while that of GAO decreased by 41 % for the same salinity increase. Regarding the stoichiometry of PAO, a decrease in the P-release/HAc uptake ratio accompanied with an increase in the glycogen consumption/HAc uptake ratio was observed for PAO when the salinity increased from 0 to 2 % salinity, indicating a metabolic shift from a poly-P-dependent to a glycogen-dependent metabolism. The anaerobic maintenance requirements of PAO and GAO increased as the salinity concentrations risen up to 4 % salinity.

Water Science and Technology, 1998

Water Science & Technology, 2007

This paper presents results of a novel application of coupling the Activated Sludge Model No. 3 (... more This paper presents results of a novel application of coupling the Activated Sludge Model No. 3 (ASM3) and the Anaerobic Digestion Model No.1 (ADM1) to assess a tropical wastewater treatment plant in a developing country (Surat, India). In general, the coupled model was very capable of predicting current plant operation. The model proved to be a useful tool in investigating various scenarios for optimising treatment performance under present conditions and examination of upgrade options to meet stricter and upcoming effluent discharge criteria regarding N removal. It appears that use of plant-wide modelling of wastewater treatment plants is a promising approach towards addressing often complex interactions within the plant itself. It can also create an enabling environment for the implementations of the novel side processes for treatment of nutrient-rich, side-streams (reject water) from sludge treatment.

Water Research, 1998

AbstractÐThis paper describes the impact of long-term (weeks) temperature changes on stoichiometr... more AbstractÐThis paper describes the impact of long-term (weeks) temperature changes on stoichiometry and kinetics of the anaerobic and aerobic phases of the biological phosphorus removal process. Steady state conversion of relevant compounds for biological phosphorus removal was studied at 20, 30, 20, 10 and 58C, following chronological order. Integrated in the process study, two methods (electron-microscopy and dry denaturing gradient gel electrophoresis) were applied to investigate the complexity of the bacterial community of biological phosphorus removing sludge cultivated at dierent temperatures. The coecient for metabolic conversions obtained from long-term temperature tests was similar to the temperature coecient observed in short-term (hours) tests (y = 1.085 versus y = 1.078, respectively).-Temperature had a moderate impact on the aerobic P-uptake process rate (y = 1.031) during long-term tests. However, a strong temperature eect on other metabolic processes of the aerobic phase, such as polyhydroxyalkanoate consumption (y = 1.163), oxygen uptake (y = 1.090) and growth (y>1.110), was observed. Dierent temperature coecients were obtained for the aerobic phase from long-term and short-term tests, probably due to a change in population structure. This change was also visible from molecular ecological studies.

Water Research, 2009

Polyphosphate-accumulating organisms (PAO) Temperature Minimum aerobic solids retention time Comp... more Polyphosphate-accumulating organisms (PAO) Temperature Minimum aerobic solids retention time Competition Metabolism Stoichiometry Kinetics a b s t r a c t Glycogen accumulating organisms (GAO) compete for substrate with polyphosphateaccumulating organisms (PAO), which are the microorganisms responsible for the enhanced biological phosphorus removal (EBPR) in activated sludge wastewater treatment systems. This can lead to the deterioration of the EBPR process. In this paper, the long-term temperature effects on the anaerobic and aerobic stoichiometry and conversion rates on adapted enriched cultures of Competibacter (a known GAO) were evaluated from 10 to 40 C. The anaerobic stoichiometry of Competibacter was constant from 15 to 35 C, whereas the aerobic stoichiometry was insensitive to temperature changes from 10 to 30 C. At 10 C, likely due to the inhibition of the anaerobic conversions of Competibacter, a switch in the dominant bacterial population to an enriched Accumulibacter culture (a known PAO) was observed. At higher temperatures (35 and 40 C), the aerobic processes limited the growth of Competibacter. Due to the inhibition or different steady-state (equilibrium) conditions reached at long-term by the metabolic conversions, the short-and long-term temperature dependencies of the anaerobic acetate uptake rate of Competibacter differed considerably between each other. Temperature coefficients for the various metabolic processes are derived, which can be used in activated sludge modeling. Like for PAO cultures: (i) the GAO metabolism appears oriented at restoring storage pools rather than fast microbial growth, and (ii) the aerobic growth rate of GAO seems to be a result of the difference between PHA consumption and PHA utilization for glycogen synthesis and maintenance. It appears that the proliferation of Competibacter in EBPR systems could be suppressed by adjusting the aerobic solids retention time while, aiming at obtaining highly enriched PAO cultures, EBPR lab-scale reactors could be operated at low temperature (e.g. 10 C). (C.M. Lopez-Vazquez), m.c.m.vanLoosdrecht@tudelft.nl (M.C.M. van Loosdrecht). 1 Present address: UNESCO Office, Jakarta, UNESCO House, Jl. Galuh (II) No. 5, Kebayoran Baru, Jakarta 12110, Indonesia.

Water Research, 2011

Hydraulic loading rate Mass loading rate Removal efficiency Soil aquifer treatment a b s t r a c ... more Hydraulic loading rate Mass loading rate Removal efficiency Soil aquifer treatment a b s t r a c t A 2000 mm long saturated laboratory soil column was used to simulate soil aquifer treatment under saturated conditions to assess the removal of chemical and biochemical oxygen demand (COD and BOD), dissolved organic carbon (DOC), nitrogen and phosphate, using high strength artificial wastewater. The removal rates were determined under a combination of constant hydraulic loading rates (HLR) and variable COD concentrations as well as variable HLR under a constant COD. Within the range of COD concentrations considered (42 mg L À1 e135 mg L À1 ) it was found that at fixed hydraulic loading rate, a decrease in the influent concentrations of dissolved organic carbon (DOC), biochemical oxygen demand (BOD), total nitrogen and phosphate improved their removal efficiencies. At the high COD concentrations applied residence times influenced the redox conditions in the soil column. Long residence times were detrimental to the removal process for COD, BOD and DOC as anoxic processes and sulphate reduction

Water Research, 2004

In biological nitrogen removal processes, nitrite can be formed and accumulated through both nitr... more In biological nitrogen removal processes, nitrite can be formed and accumulated through both nitrification and denitrification. Despite the fact that, in practice, biological phosphate removal (BPR) is often combined with biological nitrogen removal, there are only a few publications reporting the effect of nitrite on BPR. In this study, phosphateaccumulating organisms (PAO) were cultivated in an anaerobic-anoxic-aerobic sequencing batch reactor (SBR). The effect of nitrite on the enrichment of the sludge with PAO, the phosphate uptake rates and the sludge respiration was investigated. The results indicate that (1) presence of nitrite inhibits both aerobic and anoxic (denitrifying) phosphate uptake, (2) aerobic phosphate uptake was more affected than anoxic phosphate uptake, (3) presence of nitrite could be one of the factors enhancing the presence of glycogen accumulating organisms (GAO)-competitors to PAO for substrate in the anaerobic phase, and (4) it is required to monitor and control nitrite accumulation in a full-scale wastewater treatment plants. r