Wastewater treatment plants (WWTPs) are considered an entrance pathways for microplastic (MP) pollution in aquatic environments. This study reveals the removal and characteristics of MPs in wastewater from two municipal WWTPs in Indonesia. The influent contained 17.1 ± 5.65 particles L-1 (WWTP A) and 15.45 ± 4.31 particles L-1 (WWTP B), whereas the effluent contained 1.41 ± 0.01 and 1.5 ± 0.16 particles L-1. The removal efficiency was 91.75% for WWTP A and 90.32% for WWTP B, with no statistically significant difference (p > 0.05). WWTP A employed advanced treatment units, whereas WWTP B used a conventional pond-based system. MPs were characterized via light microscopy, with most particles ranging from 100–300 μm and 1000–5,000 μm. Fibers and fragments were the dominant shapes, with transparent and black being the most common colors. ATR-FTIR analysis identified polymers such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyester, and polystyrene (PS). These findings emphasize the important role of WWTPs in reducing MP pollution and highlight the need to improve treatment technologies to better protect aquatic ecosystems.

Ferruginous conditions in the Precambrian oceans gave rise to ancient iron formations that contain the oldest recognized traces of life in the form of mineral biosignatures and isotope imprints. However, these biogeochemical archives lack clear constraints on microbial diagenesis prior to lithification as metabolic functions of the primeval subsurface biosphere remain elusive. Integrating metagenomics with mineralogy, we show that microbial populations in ferruginous Lake Towuti mediate authigenic minerals (magnetite, millerite, siderite, vivianite) consistent with dissimilatory respiration types predicted from marker genes in the shallow subsurface. Syntrophic fermentation sustained long-term mineralization of reactive iron and organic carbon substrates in the deep biosphere. Ferric to ferrous diagenetic redistribution via pore water promoted isotope fractionation during burial, producing negative and positive δ56Fe signatures in end-members siderite and vivianite, and poorly reactive phases, respectively. Trophic fractionation of organic carbon during remineralization produced differential δ13C signatures in siderites, following mass balance between methane and biogenic dissolved inorganic carbon. Persistent archaea exhibited means of survival on minimal organic carbon, namely an enhanced C1 backbone metabolism grafted onto a mixotrophic Wood-Ljungdahl pathway. Metagenomic predictions thereby elucidated mineralization metabolic pathways and their target substrates responsible for biosignatures imprinted during early (20 ka) and long-term (100 ka) diagenesis. Authigenic minerals reflect specific respiration and fermentation pathways leading to diagenetic redistribution of iron and carbon isotopes during burial, according to an in-depth characterization of the deep biosphere to assess long-term evolution of pore water chemistry and iron mineralogy in a ferruginous analogue. Primary Handling Editors: D’Arcy Meyer-Dombard and Alireza Bahadori.

Ferruginous conditions prevailed in the oceans through much of Earth’s history. However, past biogeochemical cycling inferred from mineral components in ancient iron formations remain poorly constrained in terms of microbial processes prior to lithification. In Lake Towuti, Indonesia, ferruginous sediments are deposited under stratified conditions that mimic the Earth’s early oceans. Over geologic time, Lake Towuti experienced dynamic redox conditions, resulting in variable ferric and organic matter fluxes feeding microbial life at the lake floor. Although environmental conditions exert control over microbial assemblages at the time of deposition, geochemical evolution of these substrates select for specific groups of microorganisms capable of maintaining metabolic activity during entombment. The 100 m long core retrieved by the ICDP Towuti Drilling Project allowed for investigations of the subsurface biosphere, pore water geochemistry and diagenesis of iron minerals. We established the abundance and phylogenetic distribution of microorganisms along the 1 Ma stratigraphic record, and created integrated environmental and geochemical datasets in order to identify the main taxa and metabolic features involved in sediment mineralization. Ferruginous conditions predominantly selected for Bathyarchaeia. Relevant metabolisms identified from metagenome-assembled genomes indicated sulfur transformation and (homo)acetogenesis, suggesting that heterotrophic dark carbon fixation and cryptic sulfur cycling linked to iron minerals may be prominent features of microbial life in this ferruginous system. Changes in environmental processes and conditions lead to variability in metal and organic substrate concentrations with depth, while sustaining different microbial processes in various depth intervals. Geochemical profiles reflect microbial activity after deposition and demonstrated mineral precipitation induced by microbial mineralization. Precipitation of magnetite (Fe3O4), millerite (NiS), siderite (FeCO3), and vivianite (Fe3[PO4]2 · 8H2O) from pore water constitute biosignatures of microbial iron and sulfate reduction, fermentation and methanogenesis. For example, oxygen, iron, and carbon isotopes measured on siderites enabled us to differentiate between depositional and diagenetic signals. Siderite δ18O signatures reflected in-lake hydrological fluctuations. Low negative δ56Fe values recorded periods of water column stratification and oxygenation events, with minor diagenetic redistribution. Negative δ13C signatures reflected incorporation of biogenic HCO3- during organic matter fermentation, whereas positive δ13C excursions indicated mass balance due to increased production of biogenic methane.

Lake Towuti, Sulawesi, Indonesia is an ancient tectonic lake, exhibiting iron-rich, sulfate-poor anoxic deep waters. Temporal variations in water column stratification led to sediment accumulation under variable redox conditions. Such ferruginous settings make Lake Towuti an ideal study site to evaluate how a cryptic sulfur cycle could possibly operate under a scarcity of sulfate and abundance of iron minerals, similar to Earth’s primitive oceans. Here, we integrate downcore profiles for pore water geochemistry, reactive iron mineralogy, and bulk sediment elemental composition with microbial cell counts, sulfate reduction rates, 16S rRNA genes and metagenomes to resolve microbial sulfur transformations down to 15 m below lake floor (mblf). Sulfate concentrations and reduction rates dropped within the upper mblf, while pore water ferrous iron increased to its highest concentration down to 3 mblf. Any microbially-produced sulfide precipitated as reduced inorganic sulfur in the sediment, apparently forming authigenic millerite (NiS) during burial. The decrease in cell densities tracked the decline in electron acceptors in pore waters with depth. From 3 to 10 mblf, low but sustained sulfate reduction rates were observed with intermittent presence of nitrate in pore water and increased goethite in the sediment, both acting as potential oxidants of sulfur intermediates. A subsequent re-increase in pore water sulfate occurred in parallel with syntrophic fermentation of volatile fatty acids. Consistent with geochemical evolution, the taxonomic diversity of microbial populations shifted from a bacterial assemblage near the surface to selective but prevailing Bathyarchaeia down to 15 mblf. The corresponding metagenome-assembled genomes predicted metabolic potential for complete sulfate reduction (aprAB, dsrAB) in Thermodesulfovibrionia, whereas Desulfobacterota (incl. Geobacterales, Desulfuromonadales, Syntrophales) and Aminicenantia exhibited versatility in reducing iron, nitrate (narG, napA), nitrite (nirS, nrfA) and sulfate (dsrAB, asrA). By contrast, Bathyarchaeia were predicted to disproportionate sulfur to polysulfides and reduce ferredoxin via electron bifurcation (hyd I-II, sudA, dsrC, dsrE) to fuel a Wood-Ljungdahl pathway, defining homoacetogenesis as terminal electron sink. Together, these mineralogical, geochemical, and metagenomic features provide evidence for a spatially confined but active cryptic sulfur cycle with tight coupling between reduction of mineral ferric iron and intermittent pore water nitrate to syntrophic and lithotrophic (homo)acetogenesis.

Lake Rawa Pening in Central Java, Indonesia, has long been threatened by recurring water hyacinth (Eichhornia crassipes) invasion and declining water quality, both driven by intensive anthropogenic pressures in the catchment. Excessive nutrient loading from agriculture, aquaculture, domestic sewage, and land-use change accelerates sedimentation and eutrophication, creating favorable conditions for the rapid spread of water hyacinth that now covers over 70 % of the lake's surface. Using a geospatial forensic approach, this review reconstructs environmental changes from 1845 to 2025 and links them to the persistence of ecological stressors. The findings show that water hyacinth invasion has disrupted hydrological balance, reduced biodiversity, hindered fisheries, and undermined ecosystem services, while efforts to manage the weed since 2011 have remained largely ineffective. Weak governance, limited coordination among stakeholders, and insufficient funding have hampered the implementation of restoration programs and long-term management strategies. Despite these challenges, water hyacinth also provides potential benefits, including nutrient uptake for phytoremediation and utilization as raw material for compost, bioenergy, handicrafts, and livestock feed. This dual role highlights the need for integrated management that balances ecological control with socioeconomic opportunities. To secure the sustainability of its socioecological functions, Lake Rawa Pening requires a unified management authority, reduction of external nutrient inputs, adaptive use of eco-technologies, and active community participation. Strengthening preventive measures and valorizing water hyacinth biomass are key strategies for shifting from costly eradication toward sustainable restoration.

Lake Towuti, Indonesia, is an ancient stratified lake with ferruginous (iron-rich, sulfate-poor) anoxic bottom water conditions and a long depositional record affected by redox changes in the water column and sediments. As modern analogue of Earth's early ferruginous oceans, it enables the study of an active microbial subsurface biosphere and its role in organic matter and iron mineralization. Combining 16S rRNA genes, cell counts, pore water geochemistry, and bulk sediment profiles from a 100-m-long core, we present the first comprehensive characterization of the deep subsurface biosphere along a one-million-year lacustrine archive. Electron acceptors in the pore water became depleted at shallow depths, resulting in a drastic decrease in cell densities in the fermentative zone, where Bathyarchaeia dominate the microbial community composition. Although alpha and beta diversity reflected initial depletion of substrates during burial, they also varied across successive lithologies, indicating that sediment composition subsequent to deposition also affects diversity. The upper sediments (0-20 mblf) sheltered a dense and diverse microbial community involved in organic matter remineralization, actively producing and converting volatile fatty acids into carbon dioxide and methane. Deeper sediments (20-70 mblf) contained low-diversity microbial communities adapted to nutrient scarcity. In contrast, deepest lacustrine sediments (70-100 mblf) contained an increased microbial diversity reflecting greater availability of organic matter of terrestrial origin. Despite Bathyarchaeia being prime constituents of the deep subsurface biosphere, increased diversity in 16S rRNA gene composition was observed in discrete sediment layers (tephra, diatom ooze, peat). This demonstrated that depositional conditions remained traceable, while stratified microbial communities drove reductive diagenesis.

Wastewater Treatment Plants (WWTPs) are significant sources of microplastics (MPs) released into aquatic environments, highlighting the need for improved removal strategies. Constructed wetlands (CWs) have emerged as a promising nature-based solution for effectively removing MPs from wastewater. This study investigates the efficiency and underlying mechanisms of MP removal in wastewater using a horizontal subsurface flow constructed wetland (HSSF CW). Laboratory-scale experiments were conducted using six HSSF CW reactors, and the synthetic wastewater was artificially polluted with MPs. The setup was designed to examine the effects of substrate size, hydraulic retention time (HRT), and the presence of vegetation on removal performance. Results demonstrated removal efficiencies of up to 100 %, with no MPs detected in the effluent across all tested conditions. Statistical analysis showed no significant differences among the tested variables (p > 0.05), indicating comparable performance across configurations. Horizontal distribution analysis revealed a consistent decline in MPs concentration along the reactor. Contributing factors to MPs removal included plant root structures, appropriate filter media, and biofilm development. These findings highlight the potential of HSSF CW as an efficient and robust solution for reducing MP contamination in wastewater.

Most research on plastic waste has focused on lotic environments, with limited knowledge of still-water (lentic) ecosystems, especially small urban lakes. This study aimed to identify benthic macroinvertebrate communities associated with plastic waste and examine key factors regulating their structure. Conducted over 3 months in five small urban lakes, the research employed transects to collect benthic macroinvertebrates across 1 m2 areas. A total of three sampling repetitions were performed at each site in inlet and outlet. The result showed that diversity based on the Shannon-Weiner index ranged from 0.3 to 3.07 bits, correlating with high plastic waste mass and organic matter enrichment. Plastic waste disrupted ideal habitats for collector-gatherers, although other benthic groups like scrapers persisted. Despite the adverse conditions, these species adapted and dominated the sediments of small urban lakes, heavily contaminated by plastic waste and organic matter. This research highlights the significant impact of plastic pollution on benthic macroinvertebrate diversity and community structure in urban lentic environments, emphasising the need for targeted conservation and pollution mitigation strategies.

Lake Sentani is a tropical lake in Indonesia, consisting of four interconnected sub-basins of different water depths. While previous work has highlighted the impact of catchment composition on biogeochemical processes in Lake Sentani, little is currently known about the microbiological characteristics across this unique ecosystem. With recent population growth in this historically rural area, the anthropogenic impact on Lake Sentani and hence its microbial life is also increasing. Therefore, we aimed to explore the influence of environmental and anthropogenic factors on the microbial diversity of Lake Sentani. Here, we present a detailed microbiological evaluation of Lake Sentani, analyzing 49 different sites across the lake, its tributary rivers and their river mouths to assess diversity and community structure using 16S rRNA gene sequencing. Our results reveal distinct communities in lake and river sediments, supporting the observed geochemical differences. Taxonomic assessment showed the potential impact of anthropogenic pressure along the northern, urbanized shore, as river and river mouth samples revealed high abundances of Bacteroidota, Firmicutes, and Cyanobacteria, which could be attributed to pollution and eutrophication. In contrast, lake sediment communities were dominated by Thermodesulfovibrionia, Methanomethylicia, Bathyarchaeia, and Thermoplasmata, suggesting sulfate reducing, thermophilic, acidophilic bacteria and methanogenic archaea to play an important role in tropical lake systems. This study provides novel insights into ecological functions of tropical lakes and contributes to the optimization of management strategies of Lake Sentani, ensuring its holistic preservation in the future. This study evaluates microbial populations across Lake Sentani, revealing distinct communities in river and lake sediments, suggesting anthropogenic pressure effects, and offers insights for tropical lake management and preservation.

Sulfide is a crucial parameter in volcanic lakes, as its levels and fluctuations in the lake determine the origin of sulfide and the extent of its impact on the lake ecosystem. In stratified lakes, the sulfide produced tends to be retained beneath the oxic layer. The sulfides rise towards the surface as the oxic layer thins triggered by decreased water column thermal stratification. Meanwhile, the strength or weakness of thermal stratification is greatly influenced by weather conditions. Lake Maninjau is a volcanic lake with a relatively high sulfide content. Its vertical distribution in the water column is highly dependent on the stratification of the water column. When stratification disappears, sulfide rises to the surface (locally known as tubo belerang) and has a negative impact on surface biota. The objective of this study is to examine the distribution of sulfides in the water column of Lake Maninjau under two different weather conditions. We perform two surveys to measure physicochemical parameters and sulfide concentration on 26‒29 November 2022 and 25‒26 August 2023 considering the seasonal pattern. We found that air temperatures and sunshine duration combined with precipitation and wind speed drive the thermal stratification of the water column. The lower air temperature, shorter sunshine duration, higher precipitation, and stronger wind speed in the first survey (west monsoon) compared with the second survey (east monsoon) resulted in lower stratification and triggered the elevated sulfide to the surface. In the middle of the lake, the surface sulfide measured during the first survey was 4.16 µg/L. Meanwhile, in the second survey, it was only observed at 1.16 µg/L. The distribution of sulfides within the water column of Lake Maninjau is regulated by the stratification of the water column, a process directly impacted by weather conditions.

Abstract This research was carried out on the distribution and abundance of periphyton on several types of plastic in the waters of Singkarak Lake in September 2022 at three main inlets, namely the Sumpur, Paninggahan, and Sumani Rivers, as well as one outlet, namely Batang Ombilin. Periphyton was taken from several types of plastic waste submerged in the water of Singkarak Lake with an area of 16 cm2 in 3 repetitions. The surface of the plastic sample was scrubbed using a brush, then placed in a plankton bottle, then preserved using Lugol’s solution, and two drops of 4% formalin were added. Water quality, such as temperature, dissolved oxygen, pH, conductivity, nitrate, orthophosphate, total dissolve solid, turbidity, and chlorophyll, are also taken to determine environmental conditions. The composition and abundance of periphyton found in samples of several types of plastic consisted of the Bacillariophyta class ranging from 56-59.2%, then the Chlorophyta class had an abundance of between 28.5 - 34.3%, the Cyanophyta class ranged from 7.2 - 10.5% meanwhile, the Chrysophyta class is only found in 4.6% of plastic drinking glasses. The Xanthophyta class is only found in clear white plastic at 4.4%. The results of CCA ordination with MVSP software show that the periphyton abundance is distributed centrally. This indicates that the abundance of periphyton found in several types of plastic waste in the waters of Lake Singkarak is similar and there is no dominance of certain types of periphyton.

The adaptation of the phylum Chloroflexota to various geochemical conditions is thought to have originated in primitive microbial ecosystems, involving hydrogenotrophic energy conservation under ferruginous anoxia. Oligotrophic deep waters displaying anoxic ferruginous conditions, such as those of Lake Towuti, and their sediments may thus constitute a preferential ecological niche for investigating metabolic versatility in modern Chloroflexota. Combining pore water geochemistry, cell counts, sulfate reduction rates, and 16S rRNA genes with in-depth analysis of metagenome-assembled genomes, we show that Chloroflexota benefit from cross-feeding on metabolites derived from canonical respiration chains and fermentation. Detailing their genetic contents, we provide molecular evidence that Anaerolineae have metabolic potential to use unconventional electron acceptors, different cytochromes, and multiple redox metalloproteins to cope with oxygen fluctuations, and thereby effectively colonizing the ferruginous sediment-water interface. In sediments, Dehalococcoidia evolved to be acetogens, scavenging fatty acids, haloacids, and aromatic acids, apparently bypassing specific steps in carbon assimilation pathways to perform energy-conserving secondary fermentations combined with CO2 fixation via the Wood-Ljungdahl pathway. Our study highlights the partitioning of Chloroflexota populations according to alternative electron acceptors and donors available at the sediment-water interface and below. Chloroflexota would have developed analogous primeval features due to oxygen fluctuations in ancient ferruginous ecosystems. Chloroflexota populations are partitioned according to alternative electron acceptors (Anaerolineae) and donors (Dehalococcoidia) among respiratory and fermentative metabolites.

Mikroplastik dapat masuk ke Instalasi Pengolahan Air Limbah (IPAL) melalui jaringan perpipaan air limbah. Keberadaan IPAL berpotensi mengurangi jumlah mikroplastik yang masuk sebagai influen. Meski demikian, efluen IPAL masih mengandung mikroplastik dengan rentang konsentrasi yang bervariasi. Penelitian ini bertujuan untuk mengidentifikasi keberadaan mikroplastik serta karakterisasinya pada air limbah yang berasal dari IPAL perkotaan di Bojongsoang Kota Bandung. Metode pengambilan sampel, ekstraksi, kuantifikasi, dan karakterisasi dilakukan berdasarkan penelitian sebelumnya. Hasil penelitian menunjukkan bahwa mikroplastik terdeteksi di influen IPAL Bojongsoang dengan konsentrasi sebesar 15,45 partikel/liter dan berkurang menjadi sebesar rata-rata 1,49 partikel/liter di efluen. Berdasarkan bentuknya, fiber ditemukan paling dominan berada baik di influen maupun efluen, dengan kisaran 60,51-79,01%. Bentuk lainnya yang mendominasi adalah fragmen dengan rentang persentase 19,41-36,89%. Sementara, bentuk mikroplastik film, foam, dan microbead tidak banyak terdeteksi pada air limbah, dengan persentase rata-rata di bawah 5%. Mikroplastik berukuran 1000-5000 μm paling banyak ditemukan di inlet dibandingkan ukuran yang lebih kecil, dengan persentase sebesar 31,71%. Di titik outlet, mikroplastik banyak ditemukan yang berukuran di bawah 500 μm, dengan kisaran 7,27 - 24,95%. Warna mikroplastik di influen dan efluen yang ditemukan paling banyak adalah putih atau transparan (34,87 - 40,13%) dan hitam (14,54 - 23,14%). Hasil penelitian ini menunjukkan bahwa keberadaan IPAL Bojongsoang dapat menyisihkan mikroplastik yang terdapat pada air limbah secara efektif, dengan efisiensi penyisihan sebesar 89,97%.

Ferruginous conditions prevailed through Earth’s early oceans history, yet our understanding of biogeochemical cycles in anoxic iron-rich, sulfate-poor sediments remains elusive in terms of redox processes and organic matter remineralization. Using comprehensive geochemistry, cell counts and metagenomic data, we investigated the taxonomic and functional distribution of the microbial subsurface biosphere in Lake Towuti, a stratified ferruginous analogue. Below the zone in which pore water becomes depleted in electron acceptors, cell densities exponentially decreased while microbial assemblages shifted from iron- and sulfate-reducing bacterial populations to fermentative anaerobes and methanogens, mostly selecting Bathyarchaeia below the sulfate reduction zone. Bathyarchaeia encode metabolic machinery to cycle and assimilate polysulfides via sulfhydrogenase, sulfide dehydrogenase and heterodisulfide reductase, using dissimilatory sulfite reductase subunit E and rubredoxin as carriers. Their metagenome-assembled genomes showed that carbon fixation could proceed through the complete methyl-branch Wood-Ljungdahl pathway, conducting (homo)acetogenesis in the absence of methyl coenzyme M reductase. Further, their partial carbonyl-branch, assumed to act in tetrahydrofolate interconversions of C1 and C2 compounds, could support close interactions with methylotrophic methanogens in the fermentation zone. Thus, Bathyarchaeia appeared capable of coupling sulfur-redox reactions with fermentative processes, using electron bifurcation in a redox-conserving (homo)acetogenic Wood-Ljungdahl pathway, and revealing geochemical ferruginous conditions at the transition between the sulfate reduction and fermentation zone as their preferential niche.

Ancient iron formations hold important records of environmental conditions during the Precambrian Eons. Reconstructions of past oceanic systems require investigating modern ferruginous analogs to disentangle water column and diagenetic signals recorded in iron-bearing minerals. We analyzed oxygen, iron, and carbon isotopes in siderite, a ferrous carbonate phase commonly used as an environmental proxy, from a 100-m-long record spanning a one-million-year depositional history in ferruginous Lake Towuti, Indonesia. Combining bulk sediment and pore water geochemistry, we traced processes controlling siderite isotope signatures. We show that siderite oxygen isotope compositions (δ18O) reflect in-lake hydrological and depositional conditions. Low iron isotope values (δ56Fe) record water column oxygenation events over geological timescales, with minor diagenetic partitioning of Fe isotopes by microbial iron reduction after deposition. The carbon isotope compositions (δ13C) reflect incorporation of biogenic HCO3- consistent with sediment organic matter remineralization lasting over ~200 ka years after burial. Positive δ13C excursions indicate increased biogenic production of methane that escaped the sediment during low lake levels. Diffusion across the sediment-water interface during initial formations of siderite tends to align the isotope signatures of bottom waters to those of pore waters. As microbial reduction of ferric iron and oxidation of organic matter proceed and saturate pore water conditions with respect to siderite, overgrowth on nuclei partially mutes the environmental signal inherited from past bottom waters over ~1 Ma. Because high depositional fluxes of ferric iron and organic matter in early oceans would have promoted similar microbial processes in ferruginous deposits prior to lithification, the environmental record contained in siderite grains can successively integrate depositional and early diagenetic signals over short geological timescales.

A mass fish kill is often occurring in Lake Maninjau. A lack of oxygen has reportedly resulted in numerous fish kills, including the recent lake Maninjau condition. Deoxygenation of lake water is a natural phenomenon that often occurs after heavy rain events and low sunlight intensity. Additionally, during the strong wind for a long period, the decrease in oxygen could be chemically triggered by the diffusion of sulfide from the bottom layer of the water column. Furthermore, this study examines water quality parameters after the mass fish mortality occurred across locations in Lake Maninjau. Field surveys were conducted by measuring physiochemical parameters and total sulfide at the Fifteen sampling points (five points in the middle and ten points around the lake) from November 26 to December 2, 2022. They were measured directly using the Horriba©U 52 water quality checker (WQC), DO meter YSI ProDO© International and the HACH spectrophotometer DR3900 method. The results show that the average DO levels at each observation point were close to 0 mg/L while the average sulfide level on the surface was 9.5 micro g/L. The average Oxidation Reduction Potential (ORP) of -79.26 mV indicates that the lake is in a reduced state and signifies that much of the dead and decaying material in the water would be slowly broken down and decomposed. Low ORP values indicate that the compound in the water is available in reduced form, which is more toxic. Our diel DO measurement show that sunlight intensity was effective in increasing oxygen concentration in the lake.

Manufacturing activities release an extensive quantity of wastes containing hazardous materials like hexavalent chromium [Chromium VI, Cr(VI)] into the surroundings, threatening human health and the ecosystem. Fungi can be utilized as an efficient Cr(VI) remediation implement. The six isolates of dark septate endophytic (DSE) fungi (KSP, CPP, PP, DD, K.III.3.4, TKC) were evaluated for their tolerance and removal ability of various Cr(VI) concentrations (10, 30, and 50 mg/L). The quantification of Cr(VI) removal was analyzed using the 1,5-diphenylcarbazide method by UV-Visible spectrophotometer (Hitachi-U 2900). The results showed that all the DSE isolates were highly tolerant to Cr(VI) concentrations up to 50 mg/L with a tolerance index (TI) of 0.89-1.22. These fungal strains showed no significant growth (p > 0.05) from the controls. Furthermore, all test fungi exhibited an efficient removal capacity of up to 99% of 50 mg/L Cr(VI). The results indicated that DSE fungi are potential agents for bioremediation of Cr(VI) polluted surroundings like manufacturing wastewater. It is the first report on the ability of DSE fungi to remove Cr(VI).

Microplastic pollution in the marine and freshwater environment has been a global concern. The pollution in densely populated urban areas may be more severe than in any other environment, especially in areas lacking plastic waste management. Urban lakes in the Megacity of Jakarta, the capital city of Indonesia, and neighboring areas, which is the most populated city in the world, have been severely polluted by plastic waste. The urban lakes studied were located downstream of watershed areas of major rivers that outflow into Jakarta Bay, the Java Sea, and finally the ocean. To our knowledge, no studies have been reported on microplastic pollution in urban lakes in the Megacity of Jakarta. This study investigated the first occurrence of microplastics in the surface water of six urban lakes in the Megacity of Jakarta. Grab water samples were collected in either inlet or outlet areas of lakes. The water samples were pretreated and sieved to separate the microplastics. The quantification and the identification of microplastics were made using a Stereo Microscope. The most downstream urban lakes in the densely populated area close to Jakarta Bay, which is the final disposal of plastic wastes from the river canal and runoff from the surrounding area, had more microplastics than the urban lakes in the area with less population and further from the Bay. The most abundant microplastics found in the lake’s surface water was about 30,000 particles/m 3 , whereas 300 - 500 µm and the foam were the dominant size and type of microplastics discovered. The concern is that the smallest size of particles of microplastics found in the lake’s water could potentially contaminate aquatic biota, especially fish, not only in the lakes but also in Jakarta Bay, where fishing activities are substantial.

Wastewater treatment plants (WWTPs) can act as both a barrier but also as an entrance route for microplastics (MPs) into aquatic environment. This study investigated the first occurrence and characteristics of MPs in Setiabudi Jakarta WWTP. Sampling technique, extraction methods, and quantification as well as characterization of MPs was carried out based on some related previous studies. The results showed that MPs concentration detected in the influent was 17.1 (± 5.65) items/L, and it was reduced to 1.41 (± 0.01) items/L in the effluent, indicating that approximately 91.29% of MPs in raw wastewater was removed during the treatment. Based on the daily effluent discharge, it is estimated that around 352.5 of MPs are released from the WWTP each day. The light microscopic method used for quantification and characterization revealed that MPs was widely distributed in the 100–5000 μm range. The color of MPs in both influent and effluent was mainly composed of white or transparent (35%) and black (17–25.4%). Based on shape category, fibers (68–70.17%) are the dominantly found in two sampling points, followed by fragments (23.68–26.24%), films (0.71–2.9%), microbeads (0.4–1.4%) and foams (1.4–2.8%). Our findings demonstrates that the presence of Setiabudi WWTP can significantly reduce the MPs pollution from raw wastewater, however, MPs discharged into the environment was still considerably high.