Contaminants of emerging concerns (CECs) in a municipal wastewater treatment plant in Indonesia.

This study provides the first set of quantitative data on the occurrence and fate of a wide range of contaminants of emerging concerns (CECs) in Indonesia's largest wastewater treatment plant (WWTP). The WWTP employs waste stabilization ponds (WSPs) as the secondary treatment before discharging the effluent to the Citarum River. Fourteen out of twenty-two monitored CECs were detected in the wastewater influent, and seven were present in the effluent, with a total concentration of 29.8 ± 0.4 µg/L and 0.5 ± 0.0 µg/L, respectively. The occurrence of the CECs in this study was found to be well correlated with their possible use and known detection in surface waters in Indonesia. Caffeine (CAF) at 12.2 ± 0.1 µg/L, acetaminophen (ACT) at 9.1 ± 0.1 µg/L, N,N-diethyl-m-toluamide (DEET) at 5.0 ± 0.1 µg/L, ibuprofen (IBU) at 2.3 ± 0.0 µg/L, and triclosan (TCS) at 470 ± 64 ng/L were discovered as the five most prevalent CECs, followed by bisphenol A (BPA), trimethoprim (TMP), Tris(2-chloroethyl) phosphate (TCEP), sulfamethazine (SMZ), carbamazepine (CBZ), fluoxetine (FLX), benzotriazole (BTA), sulfamethoxazole (SMX), and metformin (METF). Biodegradable CECs (SMX, SMZ, ACT, IBU, TCS, BPA, CAF, DEET, and TMP) were efficiently removed (83-100%) by the WSP. In contrast, recalcitrant CECs achieved poor removal efficiencies (e.g., FLX at 24%), and for others, treatment processes even resulted in elevated concentrations in the effluent (CBZ by 85%, TCEP by 149%, and BTA by 92%). The CECs' influent concentrations were determined to pose a moderate aquatic cumulative risk, while no such risk was associated with their effluent concentrations. The study demonstrates the importance of conventional WWTPs in reducing the concentrations of CECs to minimize their aquatic contamination risk. The findings are relevant for countries, such as Indonesia, with limited resources for advanced centralized wastewater treatments, and which are exploring the efficacy of centralized WSP against the existing decentralized treatments.

Unique microbiome in organic matter-polluted urban rivers.

Approximately half of the global annual production of wastewater is released untreated into aquatic environments, which results in worldwide organic matter pollution in urban rivers, especially in highly populated developing countries. Nonetheless, information on microbial community assembly and assembly-driving processes in organic matter-polluted urban rivers remains elusive. In this study, a field study based on water and sediment samples collected from 200 organic matter-polluted urban rivers of 82 cities in China and Indonesia is combined with laboratory water-sediment column experiments. Our findings demonstrate a unique microbiome in these urban rivers. Among the community assembly-regulating factors, both organic matter and geographic conditions play major roles in determining prokaryotic and eukaryotic community assemblies, especially regarding the critical role of organic matter in regulating taxonomic composition. Using a dissimilarity-overlap approach, we found universality in the dynamics of water and sediment community assembly in organic matter-polluted urban rivers, which is distinctively different from patterns in eutrophic and oligotrophic waters. The prokaryotic and eukaryotic communities are dominated by deterministic and stochastic processes, respectively. Interestingly, water prokaryotic communities showed a three-phase cyclic succession of the community assembly process before, during, and after organic matter pollution. Our study provides the first large-scale and comprehensive insight into the prokaryotic and eukaryotic community assembly in organic matter-polluted urban rivers and supports their future sustainable management.

Effect of size variation on microbubble mass transfer coefficient in flotation and aeration processes.

Microbubble technology dramatically raises the efficiency of the flotation and aeration processes of water treatment plants (WTPs), which see extensive use in developed countries. A local institution, Indonesia Water Institute, has tried to investigate microbubble technology intended for lab-scale WTP. However, the current reactor system does not yet meet the microbubble criteria, especially as it has had few investigations of its abilities in flotation and aeration. This study aims to analyze the effect of size variations that affect the rising velocity and mass transfer coefficient (kLa) of aeration contact time. Three local spargers were used to produce microbubbles. Bubble diameters were measured optically and analyzed using ImageJ software. The dissolved oxygen (DO) concentration was measured every minute using an automated sensor so that the kLa could be determined. Of the three spargers, the smallest bubble size was produced by the vortex type with an average bubble diameter of 89 µm and the slowest rising velocity of 17.67 m/h. It also yielded the highest kLa of 0.297/min, which gave an aeration contact time of 3.64 minutes. The experimental uses of three local spargers revealed that the smaller the microbubble diameter, the higher the mass transfer coefficient in flotation and aeration processes. This research can be the basis for developing microbubble technology for WTP in Indonesia.

Sources and drivers of contamination along an urban tropical river (Ciliwung, Indonesia): Insights from microbial DNA, isotopes and water chemistry.

Wastewater treatment infrastructure is lacking in many developing countries, often resulting in high loads of contaminants discharged to urban rivers. In these countries, targeted pollution mitigation requires an understanding of where, how and when contaminants enter water bodies. Here we report on contamination of the Ciliwung River, a dynamic, tropical system flowing through the Jakarta metropolitan area (Indonesia). We measured a set of isotopic, chemical and microbial tracers in representative water and contamination sources, as well as longitudinally within the river, to assess the spatial and temporal variations in contaminant levels in and pathways to the river. In the dry season, we observed a tight coupling between locally recharged groundwater sources and the river, whereas in the wet season, one single water source originating from the fractured headwaters predominantly contributed to river flow. Yet, the flushing of upstream waters in the wet season did not always lead to the dilution of contaminants downstream. We delineated several contamination hotspots along the river, particularly active during the wet season due to higher hydrological connectivity between sources and the river. These hotspots may originate from septic tank leakage, as supported by metal ratios and dominant microbial communities, although we could not rule out other potential sources such as urban runoff or sediment resuspension. Bayesian source tracking on the whole microbial community proved useful in outlining processes that conventional tracers did not capture, such as the occurrence of a localised domestic contamination in the upper catchment, and the inflow of agricultural runoff all along the river profile during the wet season. Our study emphasises the role of rivers as biogeochemical reactors that constantly process and transform contaminants and microbial communities. We also demonstrate the value of using isotopic, chemical and microbial tools together to trace the movement of water and contaminants through urban rivers.

The nitrogen cycle in highly urbanized tropical regions and the effect of river-aquifer interactions: The case of Jakarta and the Ciliwung River.

Groundwater is extensively used in Jakarta to compensate for the limited public water supply network. Recent observations show a rise in nitrate (NO3(-)) levels in the shallow aquifer, thus pointing at a potential risk for public health. The detected levels are still below national and international regulatory limits for drinking water but a strategy is necessary to contain the growing problem. We combine 3years of available data in the Ciliwung River, the major river flowing through Jakarta, with a distributed river-aquifer interaction model to characterise the impact of urbanisation on the N-cycle of both surface and groundwater systems. Results show that the N-cycle in the river-aquifer system is heterogeneous in space, seasonal dependent (i.e. flow regime) and strongly affected by urban pollution. Results suggest also that although the main sources of N related groundwater pollution are leaking septic tanks, the aquifer interaction with the Ciliwung River may locally have a strong effect on the concentrations. In the general context of pollution control in urban areas, this study demonstrates how advanced process-based models can be efficiently used in combination with field measurements to bring new insights into complex contamination problems. These are essential for more effective and integrated management of water quality in river-aquifer systems.

X-ray absorption fine structure evidence for amorphous zinc sulfide as a major zinc species in suspended matter from the Seine River downstream of Paris, Ile-de-France, France.

Zinc is one of the most widespread trace metals (TMs) in Earth surface environments and is the most concentrated TM in the downstream section of the Seine River (France) due to significant anthropogenic input from the Paris conurbation. In order to better identify the sources and cycling processes of Zn in this River basin, we investigated seasonal and spatial variations of Zn speciation in suspended particulate matter (SPM) in the oxic water column of the Seine River from upstream to downstream of Paris using synchrotron-based extend X-ray absorption fine structure (EXAFS) spectroscopy at the Zn K-edge. First-neighbor contributions to the EXAFS were analyzed in SPM samples, dried and stored under a dry nitrogen atmosphere or under an ambient oxygenated atmosphere. We found a sulfur first coordination environment around Zn (in the form of amorphous zinc sulfide) in the raw SPM samples stored under dry nitrogen vs an oxygen first coordination environment around Zn in the samples stored in an oxygenated atmosphere. These findings are supported by scanning electron microscopy and energy dispersive X-ray spectrometry observations. Linear combination fitting of the EXAFS data for SPM samples, using a large set of EXAFS spectra of Zn model compounds, indicates dramatic changes in the Zn speciation from upstream to downstream of Paris, with amorphous ZnS particles becoming dominant dowstream. In contrast, Zn species associated with calcite (either adsorbed or incorporated in the structure) are dominant upstream. Other Zn species representing about half of the Zn pool in the SPM consist of Zn-sorbed on iron oxyhydroxides (ferrihydrite and goethite) and, to a lesser extent, Zn-Al layered double hydroxides, Zn incorporated in dioctahedral layers of clay minerals and Zn sorbed to amorphous silica. Our results highlight the importance of preserving the oxidation state in TM speciation studies when sampling suspended matter, even in an oxic water column.

Lead contamination of the Seine River, France: geochemical implications of a historical perspective.

Four sediment cores collected in the Seine River basin and dated between 1916 and 2003 were analyzed for lead concentrations and isotopic composition. In all four cores, the measured Pb concentration (up to 460 mg kg(-1)) lies significantly above the natural background (27-40 mg kg(-1)), although a significant decrease (down to 75 mg kg(-1)) was observed during the second half of the 20th century which can be explained by the reduction of lead emissions. The (206)Pb/(207)Pb ratio measured in these samples indicates that the main source of Pb used in the Paris conurbation is characterized by a "Rio Tinto" signature (defined as (206)Pb/(207)Pb=1.1634 ± 0.0001). A high contribution, up to 25%, from the leaded gasoline (characterized by (206)Pb/(207)Pb=1.08 ± 0.02) is revealed in the Seine River downstream Paris, indicating that lead from the leaded gasoline is preferentially released to the river. The dominating Pb signature in the Paris conurbation that is currently sampled through incinerators fumes ((206)Pb/(207)Pb=1.1550 ± 0.0005) and waste water treatment plant ((206)Pb/(207)Pb=1.154 ± 0.002), represents a mixture of highly recycled lead from the Rio Tinto mine and lead from leaded gasoline (imprinted by the low (206)Pb/(207)Pb of the Broken Hill mine). This signature is called "urban" rather than "industrial", because it is clearly distinct from the Pb that is found in areas contaminated by heavy industry, i.e. the heavy industries located on the Oise River which used lead from European ores characterized by high (206)Pb/(207)Pb ratios (~1.18-1.19) and possibly a minor amount of North American lead ((206)Pb/(207)Pb ratios>1.20). The "urban" signature is also found in a rural area upstream of Paris in the 1970's. At the Seine River mouth in 2003, Pb with an urban signature represents 70% of the total Pb sediment content, with the 30% remaining corresponding to natural Pb.

Bioavailability of particulate metal to zebra mussels: biodynamic modelling shows that assimilation efficiencies are site-specific.

This study investigates the ability of the biodynamic model to predict the trophic bioaccumulation of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and zinc (Zn) in a freshwater bivalve. Zebra mussels were transplanted to three sites along the Seine River (France) and collected monthly for 11 months. Measurements of the metal body burdens in mussels were compared with the predictions from the biodynamic model. The exchangeable fraction of metal particles did not account for the bioavailability of particulate metals, since it did not capture the differences between sites. The assimilation efficiency (AE) parameter is necessary to take into account biotic factors influencing particulate metal bioavailability. The biodynamic model, applied with AEs from the literature, overestimated the measured concentrations in zebra mussels, the extent of overestimation being site-specific. Therefore, an original methodology was proposed for in situ AE measurements for each site and metal.

Spatio-temporal variability of solid, total dissolved and labile metal: passive vs. discrete sampling evaluation in river metal monitoring.

In order to obtain representative dissolved and solid samples from the aquatic environment, a spectrum of sampling methods are available, each one with different advantages and drawbacks. This article evaluates the use of discrete sampling and time-integrated sampling in illustrating medium-term spatial and temporal variation. Discrete concentration index (CI) calculated as the ratio between dissolved and solid metal concentrations in grab samples are compared with time-integrated concentration index (CI) calculated from suspended particulate matter (SPM) collected in sediment traps and labile metals measured by the diffusive gel in thin films (DGT) method, collected once a month during one year at the Seine River, upstream and downstream of the Greater Paris Region. Discrete CI at Bougival was found to be significantly higher than at Triel for Co, Cu, Mn, Ni and Zn, while discrete metal partitioning at Marnay was found to be similar to Bougival and Triel. However, when using time-integrated CI, not only was Bougival CI significantly higher than Triel CI, CI at Marnay was also found to be significantly higher than CI at Triel which was not observed for discrete CI values. Since values are time-averaged, dramatic fluctuations were smoothed out and significant medium-term trends were enhanced. As a result, time-integrated concentration index (CI) was able to better illustrate urbanization impact between sites when compared to discrete CI. The impact of significant seasonal phenomenon such as winter flood, low flow and redox cycles was also, to a certain extent, visible in time-integrated CI values at the upstream site. The use of time-integrated concentration index may be useful for medium- to long-term metal studies in the aquatic environment.

Silver and thallium historical trends in the Seine River basin.

Records on pollution by metals of minor economic importance (e.g. silver and thallium) but which prove to be toxic are rarely documented in river sediment. This study used two sediment cores collected downstream of the Seine River to describe the temporal evolution of Ag and Tl concentrations in an urban catchment. Radionuclide analysis (i.e. Cs-137 and Pb-210) allowed dating sediment deposition within the cores (1933-2003). Ag concentration reached maximum values of 14.3-24.6 mg kg(-1) in the 1960s and 1970s, before gradually decreasing up to values which approximated 4 mg kg(-1) in 2003. In contrast, Tl concentrations remained roughly constant throughout the core (median value of 0.86 mg kg(-1)). Suspended solids was collected at upstream locations in the catchment to derive the background concentrations in Ag and Tl. Very high Ag concentrations were measured in the upstream Seine River sites (0.33-0.59 mg kg(-1)), compared to the values reported in the literature (0.055 mg kg(-1)). This suggests the presence of a widespread and ancient Ag pollution in the Seine River basin, as demonstrated by the very high Ag enrichment ratios recorded in the cores. Annual flux of particulate Ag in the Seine River was estimated at 1.7 t yr(-1) in 2003. In contrast, Tl concentrations remained in the same order of magnitude as the natural background signal (0.3-0.5 mg kg(-1)). This study suggests that the Seine River basin is free of Tl contamination. Future concerns should hence mostly rely on Ag contamination, in a context of increasing Ag uses and possible releases to the environment.