Algae Removal Efficiency Research Articles

Effective flocculation of harmful algae Microcystis aeruginosa by nanoscale metal–organic framework NH2-MIL-101(Cr)

Harmful algal bloom outbreak in lakes drives water-quality deterioration worldwide. Here, we recognized metal–organic frameworks (MOFs) as a potentially powerful weapon for the elimination of cyanobacterial blooms. We demonstrated that the water-stable Cr(III)-based MOFs, structured as NH2-MIL-101, could be used for removal of cyanobacterium Microcystis aeruginosa by coagulation/flocculation. The NH2-MIL-101(Cr) MOFs exhibited remarkable algal removal performance, with > 95% flocculation efficiency against M. aeruginosa within 1.5 h at 30 mg/L dosage or 3 h at 20 mg/L dosage. NH2-MIL-101(Cr) exhibited an excellent algal flocculation capacity over a wide range of pH conditions and cell densities. Especially, the algal removal capacity of NH2-MIL-101(Cr) was superior to commercial flocculants such as ferric chloride and chitosan. Furthermore, NH2-MIL-101(Cr) exhibited algal removal efficiencies of 97% after 24 h in real creek water, confirming the excellent performance of the prepared MOFs under natural conditions. The outstanding algal removal capacity of the prepared MOFs could likely be attributed to the adhesion of aggregated MOFs to the algal surface and co-precipitation with algae from the water solution. NH2-MIL-101(Cr) showed much higher algal removal efficiency compared with MIL-101(Cr), emphasizing the contribution of amine groups in algae-MOFs attachment and co-aggregation. This study presents the first account of using a water-stable MOFs as a mean of flocculant to achieve harmful algal removal, shedding new light on the potentials of MOFs in water treatment applications.

Analysis on the Effects of 3D-Printed Bio-Propeller in Algal Nutrient Removal Efficiency and Biomass Production in a Laboratory-Scale Algal-Based Wastewater Treatment

Additive Manufacturing is an emerging technology used in wide applications including, wastewater treatment. This paper presents applied techniques of Additive Manufacturing in producing a 3D-printed prototype model of a laboratory-scale wastewater treatment process. This paper aims to show the efficiency of bioremediation of freshwater algae in reducing traces of phosphate and nitrates - both known pollutants responsible for eutrophication. The study also comparatively reviews two different set-ups: stagnant and aerated. 3D printed bio-propeller, a polylactic acid-based aerator, was applied to the latter aforementioned set-up and was designed to be durable, environmental oriented, and cost-efficient. Moreover, the features and details of the 3D-printed bio-propeller emphasized its ability to promote algae harvesting by acting as a sustainable biofilm for algal growth. It is found that both set-ups show significant algae bioremediation efficiency for the synthetic nutrients. Also, the aerated set-up indicated a favorable result with the highest efficiency of 92.857% for nitrates and 41.667% for phosphate. It is concluded that the potentials of 3D printed bio-propeller as a prime component of Rotating Biological Contractor (RBC) can promote sustainable wastewater treatment.

Multi-objective optimization of ultrasonic algae removal technology by using response surface method and non-dominated sorting genetic algorithm-II

Ultrasonic technology is an environment-friendly method in algae-laden water treatment with the advantages of wonderful efficiency and no chemical additions. However, ultrasonic technology is costly and can lead to the release of algae organic matter (AOM). Few studies considered algae removal efficiency, water safety, and economy. In this study, a Response Surface Methodology (RSM) and Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) integrated method was used to investigate the influence of ultrasound parameters on algal removal efficiency band AOM release and conduct the multi-objective optimization of ultrasonic technology for satisfactory algal removal, environment protection, and improved economy. The maximum algae removal rate (ρ), minimal energy consumption, and minimal UV254 value of algal solution were calculated. Quadratic polynomial models were obtained to illustrate the relationship between ultrasonic parameters and the responses. Ultrasonic frequency was the most important factor affecting algal removal efficiency, and high frequency was beneficial for algal removal because of its contribution to the break of air bubbles. High power density significantly increased the UV254 value, and the concentration of soluble microbial metabolites and humic acid-like substances significantly increased after ultrasound. The optimization solutions calculated by NSGA-II showed low deviation from single-objective optimization solution by RSM, demonstrating that the multi-objective optimization results were reliable. This study presents a novel RSM and NSGA-II combined method in optimizing ultrasonic technology for effective, safe, and economic algal removal. The optimization results can provide references for ultrasonic parameters to be selected in practical applications.

Diatomite-enhanced coagulation for algal removal in polluted raw water: performance optimization and pilot-scale study.

Algae blooms have seriously threatened the health of aquatic ecosystems and the safety of drinking water. In this study, diatomite-enhanced coagulation technology was developed to improve the removal of algae and other pollutants. The dosage and ratio of diatomite and aluminum salts were optimized to 40mg/L and 1:1 which achieved algal removal efficiency of 98.8±0.65%. The effect of environmental factors was studied and it shows that cell density, pH, and temperature had a significant impact on algal removal. The mechanism of diatomite-enhanced coagulation was speculated to be adsorption bridging and sweep flocculation. Pilot-scale equipment was set up to verify the performance of diatomite-enhanced coagulation in engineering applications on algae polluted raw water. Results showed a better removal efficiency of algae, NH4+-N, NO2--N, and CODMn and lower operation cost than the actual operation in the Waterwork Corporation were achieved with good application prospects and promotion value.

Anti-algal activity of a fluorine-doped titanium oxide photocatalyst against Microcystis aeruginosa and its photocatalytic degradation

Fluorine-doped TiO2 was successfully synthesised and applied as algaecide. Studies on algae removal efficiencies and mechanisms illustrated that F-TiO2 was suitable for algae elimination in natural water bodies.

Using flocculation and subsequent biomanipulation to control microcystis blooms: A laboratory study

The frequent occurrence and long-term duration of Microcystis harmful algal blooms (HABs) are of great concern. Chemical flocculation is thought to be an effective way to deal with the HABs, while the application of the flocculants at a high dosage pose potential adverse impacts to the aquatic ecosystems. In this study, an alternative approach is proposed that involves the employment of polyaluminum chloride (PAC) combined with the Daphnia magna (D. magna) to achieve sustainable HABs removal efficiency with an acceptable ecological risk. It was found that under a dense Microcystis HABs (algal density of 1.5 × 107 cells/ml), a PAC dosage of 30 mg/l triggered >95% algae removal, but the released Al3+ caused 90% mortality of planktonic D. magna. Reducing the PAC dosage to 15 mg/l resulted in a slightly lower algal removal efficiency (>90%). In addition the reduced PAC dosage benefited the proliferation of the remaining unicellular algal cells, which tended to form a large colony during the 25-day experiment. Incubation of D. magna following flocculation with 15 mg/l PAC effectively grazed the remaining algal cells, meanwhile increasing the D. magna density by approximately 40-folds, and enlarging the body size by 1.37–1.50 times. This result implied that the released Al3+ was not detrimental to the D. magna. Flocculation with a reduced dosage is sufficient for colonial and large algal cells mitigation, which creates a window time for the biomanipulation of the residual tiny algae. Hence, the subsequent addition of D. magna triggered the sustainable removal of the HABs cells. The present study provides an environmentally friendly strategy for cleaning up the green tides without obvious detrimental effects on the aquatic ecosystem.

Control of Nuisance Cyanobacteria in Drinking Water Resources Using Alternative Algae-Blocking Mats

The water intake facility of Paldangho Lake (PIF), constructed in 1988, supplies drinking water to the Seoul metropolitan area and satellite city (ca. 20 million inhabitants) in South Korea. A nuisance cyanobacterial bloom (CB) has been observed every year in the PIF. Thus, related governments have been funding the control of CBs and algal-originated materials (AOMs). In this study, an algae-blocking mat (ABM) was developed to protect against CBs and AOMs considering temperature and water depth. We evaluated the daily and monthly performance of the ABM on phytoplankton, pH, dissolved oxygen, chlorophyll-a, and light intensity between April and October 2015. Although the average cell abundance of cyanobacteria between July and September approached the warning level of the Korea alert system, the highest algal removal efficiency was recorded as 92% in August when the cyanobacterial cells were over 66,000 cells/mL. On average, the ABM showed a low removal efficiency of 26% on both geosmin and 2-methylisoborneol, whereas total phytoplankton was more than 30%. In conclusion, our results indicate that the ABM may be an economical blocking tool for nuisance cyanobacteria in drinking water resources, considering AOMs and total phytoplankton.

Removal of harmful algal blooms in freshwater by buoyant-bead flotation using chitosan-coated fly ash cenospheres.

Harmful algal blooms (HABs) are a growing problem worldwide, damaging human and ecosystem health. In this study, a novel buoyant-bead flotation (BBF) method using chitosan-coated fly ash cenospheres (CFACs) was developed to remove HABs in freshwater. To achieve a high removal efficiency of harmful algae (Chlorella vulgaris, Scenedesmus quadricauda, and Microcystis aeruginosa), this study investigated the effects of chitosan/fly ash ratios in CFAC composite, CFAC concentration, flotation time, and pH values on the microalgae removal. The optimized ratio of CFACs is 0.1:12, and the optimized CFAC concentration is 0.3-0.7gL-1. However, the lower or higher ratios (0.1:4, 0.1:8, 0.1:16) result in microalgae reaching a zero-point charge too late or early, which failed to effectively remove HABs with an appropriate coal fly ash dosage. An optimized removal efficiency of 98.50% for Microcystis aeruginosa was reached at pH of 6.0. The optimized efficiency of Scenedesmus quadricauda and Chlorella vulgaris was 99.37% and 91.63%, respectively, at pH of 8.0. At neutral pH conditions, the surface charge of microalgae cells and CFACs are different, promoting aggregate formation. When CFACs were used to remove microalgae, aggregate size significantly influenced removal efficiency. Meanwhile, at the optimized pH and concentration, the removal efficiency of all three algal species exceeded 90.00% in 5min. The study highlights an efficient and inexpensive method for removing HABs and obtains the optimized operational conditions.

The effectiveness of bisulfite-activated permanganate technology to enhance the coagulation efficiency of Microcystis aeruginosa

The effects of bisulfite-activated permanganate technology (PM/BS) as a pre-oxidation process on enhancing Microcystis aeruginosa (M. aeruginosa) removal by post coagulation were investigated. The results demonstrated that pretreatment with PM/BS process effectively promoted the algae removal by coagulation with Al2(SO4)3 as the coagulant and this phenomenon was more obvious with the increase of water hardness. Compared to the sole coagulation, PM/BS pre-oxidation combing with coagulation could neutralize the zeta potential of algal cells effectively, decrease the algal cell size, and lead to the formation of more compact flocs due to the in-situ generated MnO2. The effect of oxidant dosages on algal organic matter (AOM) was also studied and no obvious release of macromolecular substances was observed with the dosage of KMnO4 increasing from 3.0 mg/L to 7.0 mg/L, suggesting the integrity of algal cells at a high KMnO4 dosage. Moreover, PM/BS pre-oxidation could lead to the decrease of most analyzed disinfection by-products (DBPs) at a Al2(SO4)3 dosage of 40.0 mg/L. The algae removal efficiency was also significantly enhanced by PM/BS pre-oxidation in the test using real algae-laden water. This study indicated that PM/BS process might be a potential assistant technology for algae removal by subsequent coagulation.

Efficient Microcystis aeruginosa removal by moderate photocatalysis-enhanced coagulation with magnetic Zn-doped Fe3O4 particles

Photocatalysis is becoming a popular method for the inactivation of algae cells. However, the previous research has mainly focused on the destruction of algae cells by photocatalysis for control of harmful blooms in natural waters. This study aims to investigate the effect of photocatalytic pretreatment on the coagulation process for Microcystis aeruginosa removal. Photocatalytic pretreatment by recyclable magnetic Zn-doped Fe3O4 particles under visible-light was indicated to enhance the algae removal efficiency from 10% to 96% with the catalyst dose of 0.05 g/L. The possible mechanism involved in the enhancement was explored by analyzing variations in the algal suspension from the aspects of cell integrity, superoxide dismutase (SOD) activity, cell morphology, and dissolved organic matter (DOM). The photocatalytic process was proved to realize moderate pretreatment of algae cells by destabilization of the algae cells without damaging cell integrity. The damaged cell ratios were all below 6% even after 360-min photocatalytic pretreatment, which could avoid the undesirable release of intracellular organic matter (IOM). The increase in SOD activity with prolonged photocatalytic time indicated that algae cells were stimulated to extensively activate SOD to resist the oxidative damage induced by the photocatalysis. Electron paramagnetic resonance (EPR) measurements further revealed that superoxide radicals were generated and involved in the photocatalytic pretreatment process. Additionally, increased DOC values in the algal suspension were induced by the desorption of mucilage from algae cells. The desorbed mucilage was proved to be mainly composed of large or medium MW rather than small MW compounds, which could further enhance the coagulation. Therefore, the efficient coagulation of algal suspensions can be realized by moderate pretreatment of M. aeruginosa via the magnetic Zn-doped Fe3O4 particle photocatalysis process.

Characteristics of wastewater treatment by Chlorella sorokiniana and comparison with activated sludge.

Characteristics of Chlorella sorokiniana treating wastewater with consideration of HRT (6 d, 16 h, 8 h), hydraulic conditions, light or dark culture were evaluated and compared with activated sludge. Results showed that optimal HRT was 8 h; if longer, effluent chemical oxygen demand (COD) and NH4 +-N in the dark began to rebound. Mixing was beneficial to COD removal of algae, while aeration was suitable for nutrient removal. Growth of C. sorokiniana in the light was mixotrophic growth and 1.3-1.7 times more than that of dark heterotrophic growth. The maximum specific growth rate (µmax), productivity, and biomass yields on COD (YCOD), N (YNH4), P (YP) of algae were higher in the light than that in the dark. COD assimilation capacity of algae was similar to activated sludge but with different dynamics. N and P assimilation capacity of algae was 1.4, 1.2-2.5 times more than activated sludge; N and P removal efficiency of algae was 5%-10%, 10%-55% respectively higher than activated sludge. This study confirmed the advantage of algae over activated sludge and reveal why algae could assist the activated sludge process.

Photocatalytic Removal of Harmful Algae in Natural Waters by Ag/AgCl@ZIF-8 Coating under Sunlight

In order to control the cyanobacterial blooms in eutrophic water, an Ag/AgCl@ZIF-8 floating coating was prepared by a dip-coating method with a sponge, innovatively employed as a carrier for the removal of algae in natural water samples. The as-prepared photocatalyst was characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). The effects of this Ag/AgCl@ZIF-8 coating on algal removal and phytoplankton community structure in natural water samples with cyanobacterial blooms were investigated under sunlight. Results showed that Ag/AgCl@ZIF-8 distributed uniformly on the surface of the coating with good stability and algae removal efficiency in water bodies. After 6 h of exposure under sunlight, the chlorophyll a in the natural water samples was degraded by 99.9%, the densities of Microcystis aeruginosa were reduced by 92.6% and the densities and biomass of the other algae decreased by about 80%. Meanwhile, the content of colored dissolved organic matter (CDOM) in the samples was decreased, effectively controlling the cyanobacterial blooms. It was found that O2•− played the main role in the photocatalytic inactivation. In conclusion, the Ag/AgCl@ZIF-8 coating has a promising application potential for the removal of harmful cyanobacteria, and provides a new idea for the control of cyanobacterial blooms in water bodies.

Ultra-sonication for controlling the formation of disinfection by-products in the ClO2 pre-oxidation of water containing high concentrations of algae.

Eutrophication has become great concern in recent years due to the fact that rivers, lakes, and reservoirs are the main drinking water source. Studies have been performed to enhance the removal of algae with ClO2 pre-oxidation, but there was high potential in the formation of chlorite and chlorate. In this study, ultra-sonication was employed to assist algae removal and control disinfection by-products formation in ClO2 pre-oxidation processes. It was found that solo ultra-sonication for 10min (algae removal 86.11 ± 2.16%) could achieve similar algae removal efficiency as that with solo ClO2 (0.5mg/L) pre-oxidation for 10min (algae removal 87.10 ± 3.50%). In addition, no formations of chlorite and chlorate were detected in solo ultra-sonication process. Five-minutes ultra-sonication followed by 5-min 0.5mg/L ClO2 treatment (total treatment time 10min; algae removal 93.55 ± 3.22%) provided a better performance on algae removal compared to the solo ClO2 (0.5mg/L) pre-oxidation for 10min. Moreover, chlorite was undetectable. It suggests that the utilization of ultra-sonication in ClO2 pretreatment for algae removal has highly prevented the formations of chlorite and chlorate.

Advantages of a ClO2/NaClO combination process for controlling the disinfection by-products (DBPs) for high algae-laden water.

Chlorine dioxide (ClO2) has been widely used in the process of preoxidation and disinfection as an excellent water treatment reagent. However, the inorganic by-products produced by ClO2, such as chlorite (ClO2-) and chlorate (ClO3-) are harmful to human health, and this has become a potential problem when using ClO2 in drinking water treatment. In this study, ClO2 alone and a ClO2/NaClO combination process were carried out to evaluate the algae removal efficiency of the treatment and the formation of disinfection by-products (DBPs: chlorite, chlorate, trihalomethanes and haloacetic acids) for high algae-laden water with 124.16µgL-1 chlorophyll a (Chl.a) content. The results show that disinfection with 1.5mgL-1 ClO2 alone results in a ClO2- concentration exceeding 0.7mgL-1. ClO2 preoxidation/ClO2 disinfection is applicable for the control of effluent quality, but the ClO2- concentration still has an excessive risk when using 0.8mgL-1 and 0.6mgL-1 ClO2 for the two process, respectively. In the ClO2/NaClO combination process, the ClO2- concentration is below 0.6mgL-1, and trihalomethane (THM) and haloacetic acid (HAA) concentrations are lower than 60% of the maximum contaminant levels (MCLs) set by the World Health Organization (WHO). Further, the formation of ClO2- is more effectively controlled by NaClO preoxidation/ClO2 disinfection than ClO2 preoxidation/NaClO disinfection.

Removal of Algae, and Taste and Odor Compounds by a Combination of Plant-Mineral Composite (PMC) Coagulant with UV-AOPs: Laboratory and Pilot Scale Studies

The seasonal occurrence of algae blooms in surface waters remains a common problem, such as taste and odor (T&Os), the risk of disinfection by-products (DBPs), and disturbance to water treatment systems. The coagulation efficiency of plant-mineral composite (PMC) coagulant followed by UV-based advanced oxidation processes (UV-AOPs; UV/H2O2 and UV/Cl2) was evaluated for removal of algae, turbidity, dissolved organic matters, and taste and odor compounds in lab-scale and pilot-scale tests. In the lab-scale test, coagulation process with 20 mg/L of PMC shows high removal efficiency of turbidity (94%) and algae (99%) and moderate removal efficiency of UV254 (51%) and geosmin (46%). The pilot test results also show good removal efficiency of turbidity (64%), chlorophyll-a (96%). After PMC coagulation process, the major water factors, which affected the performance of UV-AOPs (i.e., UV transmittance (85–94%), and scavenging factor (64,998–28,516 s−1)), were notably improved, and further degradation of geosmin and 2-methylisoborneol (2-MIB) was achieved in both lab-and pilot-scale tests of the UV-AOPs. The UV/H2O2 process shows higher removal efficiency of geosmin and 2-MIB than the UV/Cl2 process because of the pH effect. The results confirmed that the PMC-based coagulation followed by UV/H2O2 process could be an effective process for the removal of algae, geosmin, and 2-MIB.

The performance of sludge blanket clarifier against conventional settler under high water turbidity conditions

Abstract The performance of a sludge blanket clarifier was evaluated and compared to conventional settlers under high levels of turbidity and algae in the field and experimentally. Field data of sludge blanket and conventional clarifier operation were observed simultaneously for the treatment of highly turbid water. In addition, a comparison was carried out on turbidity removal efficiency, algae removal, and sludge accumulation pattern. Finally, these systems were simulated in the laboratory and operated to treat turbid water with high levels of turbidity and algae up to 80 NTU and 109cells/l respectively. Field data confirmed that the sludge blanket clarifier equipped with upper sludge cones has a high removal efficiency of turbidity and algae, ease of use and has insignificant sludge accumulation compared to the conventional settler. Further, laboratory experiments have confirmed that sludge blanket clarifier is also very effective for the treatment of high algae concentrations up to 109cells/l, with a short retention time, compared to a conventional settler, which was not effective under these conditions.

Removal Efficiency of Different Gemini Surfactants and Related Modified Clay to Chattonella marina.

To obtain new modified clays with excellent algae removal efficiency, three gemini surfactants including ethylene bis (dodecyl dimethyl ammonium chloride), ethylene bis (octadecyl dimethyl ammonium chloride) and ethylene bis (dodecyl dimethyl ammonium bromide) (EDAB), and a poly quaternary ammonium salt, poly dimethyl diallyl ammonium chloride, were screened with Chattonella marina. The four chemicals all exhibited high removal efficiencies against C. marina, with EDAB achieving the highest. A series of organ-clays with different ratios of EDAB were prepared, and the associated removal efficiencies were evaluated. The removal efficiencies of the organ-clays were improved by the EDAB intercalation and the organ-clay with 15% EDAB had the highest removal efficiency. The LC50 of EDAB intercalated clay for zebrafish and shrimp was much higher than the values of intercalated clay required to obtain a desirable removal efficiency of algae. Taken together, EDAB intercalated clay might be a potential alternative to control harmful algal blooms (HABs).

Using quartz sand to enhance the removal efficiency of M. aeruginosa by inorganic coagulant and achieve satisfactory settling efficiency

In this study, low-cost and non-polluting quartz sand was respectively mixed with AlCl3, FeCl3 and PAFC to synergistically remove Microcystis aeruginosa. Results showed that quartz sand could markedly increase the algae removal efficiency and decrease the coagulant doses. The increase of removal efficiency with AlCl3 and FeCl3 was only due to the enhancement of floc density by the quartz sand. However, the removal efficiency with PAFC was increased not only by the enhanced floc density, but also by the enlarged floc size. Flocs from 50 mg/L sand addition were larger than that with other sand doses, which was on account of the appropriate enhancement of collision efficiency at this dose. After coagulation, the extracellular organic matter (EOM) and microcystins (MCs) in system with quartz sand was remarkably reduced. That’s because quartz sand can enhance the coagulation so as to improve capping the EOM and MCs in flocs during coagulation process. Owing to 200 mg/L quartz sand could damage the cell’s membrane during coagulation proces, algal cells in the system lysed two days earlier than with 50 mg/L sand during flocs storage. In addition, cells with PAFC incurred relatively moderate cellular oxidative damage and could remain intact for longer time.

Prediction and Optimization for Wall-Flow Structure Porous Ceramic Filter on Ballast Water Treatment

In light of urgent requirement of onboard ballast water treatment, a novel wall-flow structure porous ceramic filter (PCF) has been applied with combination of UV light in our laboratory works. According to the strict criteria of International Maritime Organization (IMO) on ballast water treatment, removal efficiencies on indicator planktons should be almost 100% even at high initial densities. However, the treatment efficiencies of PCF may be greatly affected by operational conditions of the system. Hence response surface methodology (RSM) was used to evaluate the significance of the operational factors on algal removal efficiencies. Based on our previous works, flow rate, algal density and algal size were considered as three key conditional factors during PCF treatment. These three individual factors and interactive effects between each two facts were studied statistically by Minitab 15. Also, experimental studies were arranged according to full factorial design of a 6L PCF on simulated ballast water treatment at different flow rates, algal densities and algal sizes. By computational prediction and mathematical analysis, the operational conditions were optimized with first order derivation of predicted model. And by doing so, the utmost optimization was estimated to achieve higher performance of PCF system.

Peroxidation of High Algae-laden Water by Ozone: Algae Organic Matter Transformation and Disinfection By-products Formation

Formation characteristics and transferring feature of nitrogenous/carbonaceous disinfection by-products have been observed under different ozone dosages and pH conditions, and essential nature conversion of Algae organic matters has been also studied concurrently, based on high algae-laden water. The results showed as follows:reduction of Microcystis aeruginosa could reach 36% at the ozonation concentration of 28.92 mg·L-1. Humic acid-like compounds first increased and then decreased with continuing addition of ozone dosage, whereas soluble microbial products, fulvic acids and aromatic protein substance all diminished. Low dosage of ozone had certain effect on control of dichloroacetonitrile(DCAN) and trichloroacetonitrile (TCAN) formation potential, yet augmented the yield of trichloronitromethane (TCNM) and 1,1,1-trichloroacetone(1,1,1-TCP) precursors, and N-DBPs formation potential was promoted with the increase of ozone dosage. Algae removal efficiency was relatively the best under the acidic condition, meanwhile, UV254 and DOC increased with the rise of pH, though the change was not outstanding. Humic acid-like compounds decreased with the rise of pH; ozonation could degrade the soluble microbial products and the consequence was affected little by the change of pH. DCAN and TCAN formation potential decreased with the rise of pH; TCNM formation potential appeared to be the highest when the pH was 10, whereas the highest 1,1,1-TCP formation potential was found at pH 7.