Roles of Silver-Chloride Complexations in Sunlight-Driven Formation of Silver Nanoparticles.

In aerobic natural surface water, a silver ion (Ag+) exists in various Ag+-Cl- complexes because of a strong affinity for a chloride ion (Cl-); however, little information is available about the role of the Ag+-Cl- complex in the formation of silver nanoparticles (AgNPs). This study demonstrates that soluble AgClx(x-1)- species act as a precursor of AgNPs under simulated sunlight irradiation. The AgNP photoproduction increases with Cl- levels up to 0.0025 M ([Ag+] = 5 × 10-7 M) and decreases with continued Cl- level increase (0.09 to 0.5 M). At [Cl-] ≤ 0.0025 M (freshwater systems), photoproduction of AgNP correlates with the formation of AgCl(aq), suggesting that it is the most photoactive species in those systems. Matching the ionic strength of experiments containing various Cl- levels indicates that the trend in AgNP photoproduction correlates with Cl- concentrations rather than ionic strength-induced effects. The photoproduction of AgNPs is highly pH-dependent, especially at pH > 8.3. The UV and visible light portions of the solar light spectrum are equally important in photoreduction of Ag+. Overall, we show evidence that AgClx(x-1)- species irradiated under sunlight conditions contributes to the formation of nanosized silver (Ag) in the environment.

Optimization of the Determination Method for Dissolved Cyanobacterial Toxin BMAA in Natural Water.

There is a serious dispute on the existence of ß-N-methylamino-l-alanine (BMAA) in water, which is a neurotoxin that may cause amyotrophic lateral sclerosis/Parkinson's disease (ALS/PDC) and Alzheimer' disease. It is believed that a reliable and sensitive analytical method for the determination of BMAA is urgently required to resolve this dispute. In the present study, the solid phase extraction (SPE) procedure and the analytical method for dissolved BMAA in water were investigated and optimized. The results showed both derivatized and underivatized methods were qualified for the measurement of BMAA and its isomer in natural water, and the limit of detection and the precision of the two methods were comparable. Cartridge characteristics and SPE conditions could greatly affect the SPE performance, and the competition of natural organic matter is the primary factor causing the low recovery of BMAA, which was reduced from approximately 90% in pure water to 38.11% in natural water. The optimized SPE method for BMAA was a combination of rinsed SPE cartridges, controlled loading/elution rates and elution solution, evaporation at 55 °C, reconstitution of a solution mixture, and filtration by polyvinylidene fluoride membrane. This optimized method achieved > 88% recovery of BMAA in both algal solution and river water. The developed method can provide an efficient way to evaluate the actual concentration levels of BMAA in actual water environments and drinking water systems.

Reaction Pathways and Kinetics of a Cyanobacterial Neurotoxin ß-N-Methylamino-L-Alanine (BMAA) during Chlorination.

ß-N-Methylamino-L-alanine (BMAA), a probable cause of the amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC), or Alzheimer's disease, has been identified in more than 20 cyanobacterial genera. However, its removal and fate in drinking water has never been reported before. In this study, the reaction of BMAA with chlorine, a common drinking-water oxidant/disinfectant, was investigated. A liquid chromatograph coupled with a triple quadrupole mass spectrometer was employed to quantify BMAA and its intermediates. Upon chlorination, four chlorinated intermediates, each with one or two chlorines, were identified. The disappearance of BMAA caused by chlorine follows a second-order reaction, with the rate constant k1 is 5.0 × 104 M-1 s-1 at pH ∼7.0. The chlorinated intermediates were found to further react with free chlorine, exhibiting a second-order rate constant k3 = 16.8 M-1 s-1. After all free chlorine was consumed, the chlorinated intermediates autodecomposed slowly with a first order rate constant k2 = 0.003 min-1; when a reductant was added, these chlorinated intermediates were then reduced back to BMAA. The results as described shed a useful light on the reactivity, appearance, and removal of BMAA in the chlorination process of a drinking-water system.

An alternative method to quantify 2-MIB producing cyanobacteria in drinking water reservoirs: Method development and field applications.

2-Methylisoborneol (2-MIB) is a commonly detected cyanobacterial odorant in drinking water sources in many countries. To provide safe and high-quality water, development of a monitoring method for the detection of 2-MIB-synthesis (mibC) genes is very important. In this study, new primers MIBS02F/R intended specifically for the mibC gene were developed and tested. Experimental results show that the MIBS02F/R primer set was able to capture 13 2-MIB producing cyanobacterial strains grown in the laboratory, and to effectively amplify the targeted DNA region from 17 2-MIB-producing cyanobacterial strains listed in the literature. The primers were further coupled with a TaqMan probe to detect 2-MIB producers in 29 drinking water reservoirs (DWRs). The results showed statistically significant correlations between mibC genes and 2-MIB concentrations for the data from each reservoir (R2=0.413-0.998; p<0.05), from all reservoirs in each of the three islands (R2=0.302-0.796; p<0.01), and from all data of the three islands (R2=0.473-0.479; p<0.01). The results demonstrate that the real-time PCR can be an alternative method to provide information to managers of reservoirs and water utilities facing 2-MIB-related incidents.

Effect of feed starvation on side-stream anammox activity and key microbial populations.

The anaerobic ammonium oxidation (anammox) process is widely acknowledged to be susceptible to a wide range of environmental factors given the slow growth rate of the anammox bacteria. Surprisingly there is limited experimental data regarding the susceptibility of the anammox process to feed starvations which may be encountered in full-scale applications. Therefore, a study was established to investigate the impact of feed starvations on nitritation and anammox activity in a demonstration-scale sequencing batch reactor. Three starvation periods were trialled, lasting one fortnight (15 d), one month (33 d) and two months (62 d). Regardless of the duration of the starvation period, assessment of the ammonia removal performance demonstrated nitritation and anammox activity were reinstated within one day of recovery operation. Characterisation of the community structure using 16S rRNA and functional genes specific for nitrogen-related microbes showed there was no clear impact or shift in the microbial populations between starvation and recovery phases.

Congener profiles of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in sediment, water, and fish at a soil contamination site in Taiwan.

The relationship of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in sediment, water, and fish was studied for 55 fish farms near a contaminated site in Tainan, Taiwan. Samples were collected from the farms and analyzed for seventeen 2,3,7,8-substituted PCDD/Fs congeners. High correlations were found between PCDD/Fs in water and sediment in regard to both concentration and toxicity (R(2) = 0.933 for concentration and R(2) = 0.832 for toxicity). The congener profiles of the 17 PCDD/Fs in water were similar to those in the sediment. However, the PCDD/Fs congener composition in the fish and fish belly samples were different from those in the sediment and water samples obtained from the same fish farm and were also different among the fish samples. It is thus suggested that the biotic PCDD/Fs distribution is more complex than the abiotic PCDD/Fs distribution. Among the seven factors analyzed, only the lipid percentage presented a relationship with the PCDD/Fs congener composition in the fish and fish bellies. A multiple linear regression of the concentration of each congener in the fish was conducted using the concentration of each congener in the site-matched sediment and the lipid content of the fish as independent variables. The results showed that only seven PCDD/Fs congeners with a lower degree of chlorination, which were 4-6 chlorine substitutes, in the fish presented a significant correlation with the lipid content in the fish and their concentration in sediment (r > 0.65, P < 0.005 for both independent variables). In addition, the octanol-water partition coefficients were not significantly related to this distribution behavior.

Resolution of Adsorption and Partition Components of Organic Compounds on Black Carbons.

Black carbons (BCs) may sequester non-ionic organic compounds by adsorption and/or partition to varying extents. Up to now, no experimental method has been developed to accurately resolve the combined adsorption and partition capacity of a compound on a BC. In this study, a unique "adsorptive displacement method" is introduced to reliably resolve the adsorption and partition components for a solute-BC system. It estimates the solute adsorption on a BC by the use of an adsorptive displacer to displace the adsorbed target solute into the solution phase. The method is validated by tests with uses of activated carbon as the model carbonaceous adsorbent, soil organic matter as the model carbonaceous partition phase, o-xylene and 1,2,3-trichlorobenzene as the reference solutes, and p-nitrophenol as the adsorptive displacer. Thereafter, the adsorption-partition resolution was completed for the two solutes on selected model BCs: four biochars and two National Institute of Standards and Technology (NIST) standard soots (SRM-2975 and SRM-1650b). The adsorption and partition components resolved for selected solutes with given BCs and their dependences upon solute properties enable one to cross-check the sorption data of other solutes on the same BCs. The resolved components also provide a theoretical basis for exploring the potential modes and extents of different solute uptakes by given BCs in natural systems.

Exposure of Microcystis aeruginosa to Hydrogen Peroxide under Light: Kinetic Modeling of Cell Rupture and Simultaneous Microcystin Degradation.

The effect of hydrogen peroxide on the cell integrity of a cyanobacterium, Microcystis aeruginosa, and on the release and degradation of microcystins (MCs) under simulated sunlight was investigated. The cyanobacterium was exposed to H2O2 in the range of 0-60 mg·L(-1) for 3.5 h. Production of OH radical in the solution was estimated by a chemical probe method. More than 99% (2 log) of the M. aeruginosa cells were ruptured or damaged by 3 h for all the treatments. Loss of cell integrity over time revealed two distinct phases. Cells retained their integrity during the initial lag phase and rapidly ruptured following first-order reaction afterward. A linear relationship was found between the duration of the lag phase and the steady-state concentration of OH radical. Release of MCs was closely correlated with the loss of cell integrity. Sequential reaction models were developed to simulate the release and degradation of MCs. These models were able to quantitatively describe the kinetics of all reactions under different H2O2 doses and extended exposure time. In particular, the models successfully predicted the concentration change of MCs using independently measured parameters. These models provide a simple and quantitative means to estimate the interaction of oxidants and cells and the consequent release of metabolites during oxidation treatment of cyanobacterium-laden waters.

Kinetics of cell inactivation, toxin release, and degradation during permanganation of Microcystis aeruginosa.

Potassium permanganate (KMnO4) preoxidation is capable of enhancing cyanobacteria cell removal. However, the impacts of KMnO4 on cell viability and potential toxin release have not been comprehensively characterized. In this study, the impacts of KMnO4 on Microcystis aeruginosa inactivation and on the release and degradation of intracellular microcystin-LR (MC-LR) and other featured organic matter were investigated. KMnO4 oxidation of M. aeruginosa exhibited some kinetic patterns that were different from standard chemical reactions. Results indicated that cell viability loss and MC-LR release both followed two-segment second-order kinetics with turning points of KMnO4 exposure (ct) at cty and ctr, respectively. KMnO4 primarily reacted with dissolved and cell-bound extracellular organic matter (mucilage) and resulted in a minor loss of cell viability and MC-LR release before the ct value reached cty. Thereafter, KMnO4 approached the inner layer of the cell wall and resulted in a rapid decrease of cell viability. Further increase of ct to ctr led to cell lysis and massive release of intracellular MC-LR. The MC-LR release rate was generally much slower than its degradation rate during permanganation. However, MC-LR continued to be released even after total depletion of KMnO4, which led to a great increase in MC-LR concentration in the treated water.

First principles modelling of the ion binding capacity of finger millet.

Finger millet, a cereal grain widely consumed in India and Africa, has gained more attention in recent years due to its high dietary fibre (arabinoxylan) and trace mineral content, and its climate resilience. The aim of this study was to understand the interactions between potassium (K+), calcium (Ca2+) and zinc (Zn2+) ions and the arabinoxylan structure and determine its ion-binding capacity. Three variations of a proposed model of the arabinoxylan structure were constructed and first principles Density Functional Theory calculations were carried out to determine the cation-binding capacity of the arabinoxylan complexes. Zn2+-arabinoxylan complexes were highly unstable and thermodynamically unfavourable in all three models. Ca2+ and K+ ions, however, form thermodynamically stable complexes, particularly involving two glucuronic acid residues as a binding pocket. Glucuronic acid residues are found to play a key role in stabilising the cation-arabinoxylan complex, and steric effects are more important to the stability than charge density. Our results highlight the most important structural features of the millet fibre regarding ion-storage capacity, and provide valuable preliminary data for confirmatory experimental studies and for the planning of clinical trials where the bioavailability of bound ions following digestion may be tested.

Performances of full-scale biological nitrogen pre-treatment process for drinking water source: Seasonal variations and microbial community.

This study investigated the performance of the full-scale unit over a two-year period to enhance nitrification efficiency and provide operational strategies. Results indicated that raw water quality from Donggan River was notably influenced by seasonal variations, particularly during dry and wet seasons, impacting the nitrification efficiency of the biological pretreatment process. Factors such as influent concentrations of ammonia and total Kjeldahl nitrogen were found to have significant effects on nitrification, with temperature and conductivity also showing correlations. The specific rate of ammonia removal was calculated to be approximately 0.1 kg-N/m3/d under the existing operational setup. Moreover, elevating dissolved oxygen levels above 4 mg/L was proposed to potentially boost ammonia oxidation based on findings from experiments conducted in lab-scale bioreactors. In times of increased influent ammonia levels, the elimination of about 1-3 mg-N/L of total nitrogen signified the activation of denitrification processes. This observation was corroborated by results from next-generation sequencing techniques, verifying the existence of denitrifying microorganisms. The real-time PCR analysis results indicated that the abundance of comammox amoA gene was comparable with the abundance of the AOB amoA gene, indicating the presence of comammox Nitrospira and their potential role on nitrification in the system.

Characterization of typical taste and odor compounds formed by Microcystis aeruginosa.

Production and characteristics of typical taste and odor (T&O) compounds by Microcystis aeruginosa were investigated. A few terpenoid chemicals, including 2-MIB, beta-cyclocitral, and beta-ionone, and a few sulfur compounds, such as dimethyl sulfide and dimethyl trisulfide, were detected. beta-Cyclocitral and beta-carotene concentrations were observed to be relevant to the growth phases of Microcystis. During the stable growth phase, 41-865 fg/cell of beta-cyclocitral were found in the laboratory culture. beta-Cyclocitral concentrations correlated closely with beta-carotene concentrations, with the correlation coefficient R2 = 0.96, as it is formed from the cleavage reaction of beta-carotene. For dead cell cases, a high concentration of dimethyl trisulfide was detected at 3.48-6.37 fg/cell. Four T&O compounds, including beta-cyclocitral, beta-ionone, heptanal and dimethyl trisulfide, were tested and found to be able to inhibit and damage Microcystis cells to varying degrees. Among these chemicals, beta-cyclocitral has the strongest ability to quickly rupture cells.

Detection and quantification of major toxigenic Microcystis genotypes in Moo-Tan reservoir and associated water treatment plant.

Two molecular methods, denaturing gradient gel electrophoresis (DGGE) and quantitative real-time polymerase chain reaction (qPCR) with the Universal ProbeLibrary (UPL) probe, were developed and used for the characterization and quantification of several microcystin producers in Moo-Tan Reservoir (MTR), Taiwan and its associated water treatment plant (Shih-Men Water Treatment Plant, SMWTP). Internal transcribed spacer (ITS) sequence, a highly diversified region between the 16S rRNA and 23S rRNA genes, was used to further identify the isolated strains from MTR and also used in DGGE for the detection of the specific DNA fragments and biomarkers for 11 strains observed in MTR. These ITS-DGGE biomarkers were successfully applied to monitor the community changes of potential toxigenic Microcystis sp. over a period of five years. Two highly specific primers were combined with UPL probes to measure microcystins synthesis gene (mcyB) and phycocyanin intergenic spacer region (cpcB) concentrations in water samples. The copy concentrations of UPL-mcyB and UPL-cpcB correlated well with MC-RR concentrations/water temperature and Microcystis sp. cell numbers in the water samples, respectively. For SMWTP, toxin concentrations were low, but the DGGE bands clearly demonstrated the presence of potential microcystin producers in both water treatment plants and finished water samples. It was demonstrated that toxigenic Microcystis sp. may penetrate through the treatment processes and pose a potential risk to human health in the drinking water systems.

Challenges in Environmental Science/Engineering and fate and innovative treatment/remediation of emerging pollutants.

Solid waste Management: There are two articles in this section. Shi et al. (2021) investigated the unbalanced status and multidimensional influences of municipal solid waste management in Africa. It was identified that economic growth, urbanization and geographical location are the most critical factors influencing the unbalanced statue of MSW management in Africa.

Degradation of bisphenol-A using ultrasonic irradiation assisted by low-concentration hydrogen peroxide.

This study investigated the degradation of bisphenol-A (BPA) by ultrasonic irradiation in the presence of different additives (H2O2, air bubbles and humic acid) under various operating conditions, i.e., ultrasonic frequency, power intensity and power density. The results demonstrated that the BPA degradation followed pseudo first-order kinetics under different experimental conditions. The optimum power intensities were 0.9, 1.8, and 3.0 W/cm2 at the frequencies of 400, 670, and 800 kHz, respectively. At the fixed frequency (800 kHz), the degradation rate of BPA was shown proportional to the increase of power density applied. With this manner, the BPA sonolysis could be facilitated at H2O2 dosage being lower than 0.1 mmol/L; while BPA degradation was hindered at H2O2 concentration in excess of 1 mmol/L. Additionally, BPA removal was shown to be inhibited by the presence of aeration and humic acid during ultrasonic irradiation. The present study suggested that the degradation rate of BPA assisted by ultrasonic irradiation was influenced by a variety of factors, and high BPA removal rate could be achieved under appropriate conditions.

Combined impact of silver nanoparticles and chlorine on the cell integrity and toxin release of Microcystis aeruginosa.

Silver nanoparticles (AgNPs) have shown to be toxic to freshwater cyanobacterial species, and sodium hypochlorite (NaOCl) is a common oxidant for the treatment of cyanobacterial cells. AgNPs have a high possibility of co-existing with the cyanobacterial cells in the aqueous environments leading to its exposure to NaOCl during water treatment; however, their combined effects on the cyanobacterial cells are largely undocumented. This work compares the individual and combined effect of AgNP and NaOCl on the integrity and toxin (microcystins) release of Microcystis aeruginosa at varying levels. The results show that the AgNP (0.2-0.6 mg/L) alone has negligible effects on the cell lysis, while NaOCl alone shows concentration-dependent (0.2 < 0.4 < 0.6 mg/L) rupturing of cells. In contrast, the AgNP + NaOCl (0.2-0.6 mg/L) samples show increasing loss in cell integrity at higher AgNP (0.4 and 0.6 mg/L) levels than the NaOCl only samples. NaOCl exposure results in increasing dissolution of AgNPs with time, releasing silver ions (Ag+), affecting its size and morphology. The cell-associated total Ag declines over time with an increase in NaOCl levels, maybe due to increasing cell-lysis or NaOCl induced oxidative dissolution of AgNPs. The cell-associated total Ag and released Ag+ possibly weaken the cellular membrane, thus assisting NaOCl in faster cell-lysis. The combined exposure of AgNP and NaOCl also results in a higher release of toxin from the cells. This work collectively reveals that the AgNPs combined with NaOCl can enhance the cell lysis and release of toxins.

Quantitative PCR based detection system for cyanobacterial geosmin/2-methylisoborneol (2-MIB) events in drinking water sources: Current status and challenges.

Taste and odor (T&O) are an important issue in drinking water, aquaculture, recreation and a few other associated industries, and cyanobacteria-relevant geosmin and 2-methylisoborneol (2-MIB) are the two most commonly detected T&O compounds worldwide. A rise in the cyanobacterial blooms and associated geosmin/2-MIB episodes due to anthropogenic activities as well as climate change has led to global concerns for drinking water quality. The increasing awareness for the safe drinking, aquaculture or recreational water systems has boost the demand for rapid, robust, on-site early detection and monitoring system for cyanobacterial geosmin/2-MIB events. In past years, research has indicated quantitative PCR (qPCR) as one of the promising tools for detection of geosmin/2-MIB episodes. It offers advantages of detecting the source organism even at very low concentrations, distinction of odor-producing cyanobacterial strains from non-producers and evaluation of odor producing potential of the cyanobacteria at much faster rates compared to conventional techniques.The present review aims at examining the current status of developed qPCR primers and probes in identifying and detecting the cyanobacterial blooms along with geosmin/2-MIB events. Among the more than 100 articles about cyanobacteria associated geosmin/2-MIB in drinking water systems published after 1990, limited reports (approx. 10 each for geosmin and 2-MIB) focused on qPCR detection and its application in the field. Based on the review of literature, a comprehensive open access global cyanobacterial geosmin/2-MIB events database (CyanoGM Explorer) is curated. It acts as a single platform to access updated information related to origin and geographical distribution of geosmin/2-MIB events, cyanobacterial producers, frequency, and techniques associated with the monitoring of the events. Although a total of 132 cyanobacterial strains from 21 genera and 72 cyanobacterial strains from 13 genera have been reported for geosmin and 2-MIB production, respectively, only 58 geosmin and 28 2-MIB synthesis regions have been assembled in the NCBI database. Based on the identity, geosmin sequences were found to be more diverse in the geosmin synthase conserved/primer design region, compared to 2-MIB synthesis region, hindering the design of universal primers/probes. Emerging technologies such as the bioelectronic nose, Surface Enhanced Raman Scattering (SERS), and nanopore sequencing are discussed for future applications in early on-site detection of geosmin/2-MIB and producers. In the end, the paper also highlights various challenges in applying qPCR as a universal system of monitoring and development of response system for geosmin/2-MIB episodes.

Precision early detection of invasive and toxic cyanobacteria: A case study of Raphidiopsis raciborskii.

Blooms of the toxic cyanobacterium, Raphidiopsis raciborskii (basionym Cylindrospermopsis raciborskii), are becoming a major environmental issue in freshwater ecosystems globally. Our precision prevention and early detection of R. raciborskii blooms rely upon the accuracy and speed of the monitoring method. A duplex digital PCR (dPCR) monitoring approach was developed and validated to detect the abundance and toxin-producing potential of R. raciborskii simultaneously in both laboratory spiked and environmental samples. Results of dPCR were strongly correlated with traditional real time quantitative PCR (qPCR) and microscopy for both laboratory and environmental samples. However, discrepancies between methods were observed when measuring R. raciborskii at low abundance (1 - 105 cells L - 1), with dPCR showing a higher precision compared to qPCR at low cell concentration. Furthermore, the dPCR assay had the highest detection rate for over two hundred environmental samples especially under low abundance conditions, followed by microscopy and qPCR. dPCR assay had the advantages of simple operation, time-saving, high sensitivity and excellent reproducibility. Therefore, dPCR would be a fast and precise monitoring method for the early warning of toxic bloom-forming cyanobacterial species and assessment of water quality risks, which can improve prediction and prevention of the impacts of harmful cyanobacterial bloom events in inland waters.

In situ measurement of odor compound production by benthic cyanobacteria.

A simple technique was developed to make in situ measurements of emission rates of two common odorants, 2-MIB and geosmin, and was validated with different natural communities of benthic cyanobacterial mats in Hope Valley Reservoir (HVR), South Australia, and Kin-Men Water Treatment Plant (TLR-WTP), Taiwan. A pair of parallel columns was used to differentiate between emission and loss rates caused by biodegradation, volatilization, and other mechanisms. Experimental results indicated that the loss rates followed a first-order relationship for all cases tested, with biodegradation and volatilization being the key mechanisms. The loss rates were comparable to those reported in the literature for biodegradation and those calculated from two-film theory for volatilization. After accounting for the loss rates, the net emission of geosmin and 2-MIB was estimated from experimental data. Odorant emission rates on the basis of column surface area, cyanobacterial cell number, and chlorophyll a (chl-a) were 4.2-4.4 ng h(-1) cm(-2), 1.0-5.5 x 10(-6) ng h(-1) cell(-1), and 3.2-3.5 ng h(-1)microg-chl(-1), respectively for 2-MIB released from benthic mats in TLR-WTP, and, 18-190 ng h(-1) cm(-2), 0.053-1.8 x 10(-3) ng h(-1) cell(-1), and 48-435 ng h(-1)microg-chl(-1) respectively for geosmin from benthic mats in HVR. The method developed provides a simple means to estimate the emission rates of odorants and possibly other algal metabolites from benthic cyanobacterial mats.

Biodegradation of MIB and geosmin with slow sand filters.

This study evaluated the biodegradation of MIB (2-methylisoborneol) and geosmin (trans-1,10-dimethyl-trans- 9-decalol) in simulated slow sand filtration (SSF) columns and in batch reactors. The results showed that both MIB and geosmin were biodegradable in the two systems. In batch experiments, the overall removals for MIB and geosmin were 50% and 78%, respectively, after 7 days of contact time. Volatilization loss plays an important role for geosmin in batch systems. Simulated SSF column studies also showed that more than 50% of geosmin and MIB were degraded by the microbial on the sand surface of a slow sand filter. With a filtration rate of 5 m/day, the simulated SSF degraded MIB from 48% to 69% and geosmin from 87% to 96%. The rapid biodegradation of MIB and geosmin in SSF column tests was attributed to the use of filter sands from the SSF unit in the Kinmen water treatment plant, where the microbial had been acclimated to both MIB and geosmin. The results also showed that more than 70% of the geosmin was removed in the top portion of the filter ( approximately 10 cm); while the removal of MIB occurred throughout the entire column depth. The results of this study demonstrated that slow flow through preacclimated sand was effective for control of MIB and geosmin in drinking water.