HA Removal Research Articles

Two-stage injection of polymer and microsand during ballasted flocculation for treating kaolin waters with or without humic acid: Floc evolutional characteristics, performance and mechanisms

Ballasted flocculation is regarded as a most promising water treatment technology in aspects of retrofit and high-rate applications. To deep understand the incorporation behaviors of ballasting agent into ballasted floc growth, two distinct injection modes (namely a two-stage injection of polyacrylamide (PAM) alone, and a two-stage injection of both PAM and microsand) were developed in this study. Then, ballasted flocculation tests of kaolin and kaolin-HA (humic acid) waters were conducted at varying split ratios for fixed total dosages of both PAM and microsand. The experimental results showed that for either two-stage injection mode, the higher the second percentage of each split ratio, the greater the average size of maturated flocs at the second sub-stage of maturation. Meanwhile, the turbidity and UV254 values of settled water became lower at 30 and 180 s of sedimentation, suggesting that varying split ratios significantly affected the kinetics of ballasted floc growth. Moreover, it was suggested that the selection of either two-stage injection mode or corresponding split ratios played a more pronounced role in the HA removal than the total dosage of PAM. This suggestion was supported by SEM, FTIR and XPS analyses for surface morphological details, functional groups and chemical states of maturated flocs eventually formed in the kaolin-HA water through both two-stage injection modes. Accordingly, newly-established conceptual models of ballasted floc growth were proposed to explore the potential influencing mechanisms of varying split ratios on the ballasted flocculation performance. At each sub-stage of maturation, an appropriate dosage ratio between PAM and microsand was of great importance to effectively incorporate microsand particles into ballasted floc formation, besides the hydrolyzed produces of AS coagulant formed at the coagulation stage of ballasted flocculation. This study is expected to provide valuable insights for making ballasted flocculation more effective, economical and sustainable in water treatment engineering.

Unveiling the role of cake layer in coagulation-ultrafiltration on membrane fouling and emerging application as dynamic membrane before ultrafiltration

Cake layer is considered to play a crucial role in membrane fouling during the coagulation-ultrafiltration process. However, the contribution of the cake layer on membrane fouling and probable natural organic matter (NOM) removal in this process is unclear, leading to a limited understanding of cake layer and potential secondary utilization. Here, ultrafiltration (UF) membrane fouling contribution, NOM removal, and dynamic membrane application of the cake layer were investigated. Results showed reversible fouling was dominated by cake layer, whereas irreversible fouling was determined by both cake layer and residual NOM in coagulation effluent. Compared with direct UF, the cake layer improved approximately by 15 % of HA removal with molecular weight (MW) of 2000–4000 Da. By optimizing membrane material, HA removal and membrane fouling alleviation were synchronously achieved by cake layer deposition-UF. According to mechanisms analysis, HA removal was attributed to the adsorption or interception of HA with larger MW by the cake layer. Zeta potential and fractal dimension of flocs, and contact angle of the cake layer were closely related to HA removal by cake layer, whereas reversible and irreversible fouling were positively correlated with cake layer thickness and floc fractal dimension respectively. Compared with other dynamic membranes, the cake layer had the best economic performance, which provided application potential on NOM removal in micro-polluted surface water.

Enhanced simultaneous phosphate recovery and organics removal by a nucleation crystallization pelleting process

Naturally co-occurring phosphate (P) and dissolved organic matter (DOM) in raised livestock wastewater have caused increasing public concerns. This study fabricated a novel nucleation crystallization pelleting process (NCP) showing orientated P recovery and HA (as a major fraction of DOM) removal from wastewater. Results showed that after 120 h of continuous operation, the total removal efficiency of P and HA stabilized at 97.5 % and 92 %, respectively, by using a three-stage NCP process. The NCP results further demonstrated that the main recovery mechanism of P involves surface-induced precipitation of P in the form of hydroxyapatite (HAP) on the seed surface by modulating the supersaturation of HAP in the system. The FTIR, SEM-EDS, and XPS analysis combined with DFT calculations revealed the molecular-level mechanisms for removing HA, which were mainly controlled by Calcium ions bridging, H-bonding, and π-π stacking. More importantly, the attached HAP on the seed surface would enhance the mutual interaction with HA, further enhancing the removal efficiency of HA. This contribution not only opens a high potential avenue for further research on the simultaneous capture of P and organic matter but also sheds light on the development of the practical application of the NCP remediation strategies.

Hydrophilic membranes for effective removal of PFAS from water: Anti-fouling, durability, and reusability

Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants in natural water. The polyacrylonitrile ultrafiltration membrane with an average pore size of 10.9 nm, grafted with tertiary amino groups, and subsequently quaternized, was developed to effectively adsorb PFAS in the presence of co-existing competitors. It achieved over 98 % removal of perfluorooctane sulfonic acid (PFOS) at neutral pH. Over 90 % removal efficiency was recovered within four cycles through eluent regeneration. The removal mechanism was determined, through advanced characterization and theoretical analysis, as a synergistic process of electrostatic, hydrophobic, and dipole-dipole interactions. To address potential competition in adsorption caused by natural organic matter (NOM), membrane pores were regulated to achieve selective interception of humic acid (HA, a representative NOM). Effective PFOS removal (98.4 %) maintained in the presence of abundant competitors. Furthermore, the mild regeneration method led to a flux recovery rate of 99.0 %, underscoring its resistance to contamination. The effects of versatile NOM and surfactants were also evaluated, that insignificant reduction in removal efficiency was observed. After 144th regeneration cycles (equivalent), <15 % changed in grafting moieties and <13.5 % decreased in HA removal were observed, suggesting the durability on chemical composition and interception ability. Overall, the adsorptive membranes, with reusability, anti-fouling, and durability, showed great potential for remediation of PFAS from natural water.

Salt tide affecting algae-laden micropolluted surface water treatment and membrane performance based on BDD electro-oxidation coupled with ceramic membrane process

Harmful algal blooms pose an emerging threat to freshwater ecological security and human health, necessitating further study in offshore areas. In this work, boron-doped diamond electro-oxidation (BDD/EO) coupled with a ceramic membrane filtration was employed aiming to assess the salt tide affecting algae-laden water treatment involving with various natural organic matters (e.g., HA, SA, and BSA). The results have demonstrated that BDD/EO remove chlorophyll from the algae-laden water effectively due to the inactivation of algal cells. Moreover, considering the influence of salt tide, NH3–N would be mainly oxidized through the in-situ generated active chlorine at the electrode-liquid interface. In addition, in three kinds of salt tide affecting algae-laden water, TOC content in BSA group was decreasing remarkably after BDD/EO with TOC removal efficiency above 80%; while those in HA and SA groups had no obvious reducing due to the more algae cells breakage synchronous with HA and SA removal. Based on the fluorescent characteristics and particle size distribution, the generated small molecular organics after electro-oxidation might raise the pore blockage probability and the hydrophobic organic and fluorescent substances were preferentially oxidized in BDD/EO process being beneficial to reducing membrane fouling. Besides, the membrane special flux in three groups were decreasing significantly and the irreversible fouling resistance in SA group accounted for a larger proportion of the total resistance than those of HA and BSA. At last, in BDD/EO-CM process, macromolecular substances degradation rate was greater than that of small molecules based on the molecular weight distribution in three groups of salt tide affected algae-laden water treatment. In a word, this work provides effective and innovative strategies for the harmful algal bloom control and contributes interesting insights of membrane fouling performance of electrochemical coupled ultrafiltration membrane process.

Electroactive membrane with the electroactive layer beneath the separation layer to eliminate the interference of humic acid in the oxidation of antibiotics

Removing harmful antibiotics is essential to reclaiming water from municipal secondary effluent. Electroactive membranes are effective in the removal of antibiotics but challenged by the abundant coexisting macromolecular organic pollutants in municipal secondary effluent. To eliminate the interference of macromolecular organic pollutants in the removal of antibiotics, we propose a novel electroactive membrane with a top polyacrylonitrile (PAN) ultrafiltration layer and a bottom electroactive layer composed of carbon nanotubes (CNTs) and polyaniline (PANi). When filtering the mixture of tetracycline (TC, a typical antibiotic) and humic acid (HA, a typical macromolecular organic pollutant), the PAN-CNT/PANi membrane performed sequential removal. It retained HA at the PAN layer (by ∼96%) and allowed TC to reach the electroactive layer where it was electrochemically oxidized (e.g., by ∼92% at 1.5 V). The TC removal of the PAN-CNT/PANi membrane was marginally affected by HA, unlike that of the control membrane with the electroactive layer on the top that showed decreased TC removal after the addition of HA (e.g., decreased by 13.2% at 1 V). The decreased TC removal of the control membrane was attributed to the attachment (but not competitive oxidation) of HA on the electroactive layer that impaired the electrochemical reactivity. The HA removal prior to TC degradation realized by the PAN-CNT/PANi membrane avoided the attachment of HA and guaranteed TC removal on the electroactive layer. Long-term filtration for 9 h revealed the stability of the PAN-CNT/PANi membrane, and its advantageous structural design was conformed in the context of real secondary effluents.

Black Water Purification by Activated Carbon from Ilalang Weeds (Imperata cylindrica) Adsorbent in Peatland Rural Area

The black water containing humic acid, HA in peat land rural area is a serious issue. This study aims to synthesis of activated carbon, AC from Ilalang Weeds, IW (Imperata cylindrica) as low-cost adsorbent for HA. The success AC synthesis by H3PO4 activator from IW was evidently characterized by Fourier Transform Infra-Red, FTIR and Scanning Electron Microscopy, SEM. The effects of pH solution, initial HA concentration, and contact time were systematically studied to investigate the performance of Activated Carbon from Ilalang Weeds, ACIW. The results showed the increasing of Langmuir monolayer capacity of HA adsorption on carbon from IW before (49.75 mg g-1) and after (56.82 mg g-1) activation process at the pH optimum 6.0. The equilibrium adsorption data fitted with the isotherm model was shifted from multilayer Freundlich model (CIW) into monolayer Langmuir model as the consequences of increasing pore diameter size and active sites intensity. Calculation of adsorption energy by Dubinin-Radushkevich (EDR) model, 0.50 and 2.24 kJ mol-1 for CIW and ACIW, respectively, showed the increasing of physical affinity of HA with the active sites of adsorbent. Adsorption kinetics showed that the adsorption behavior followed the Ho pseudo-second-order kinetic model. The experimental results of this work demonstrate that the ACIW can be used as a promising low-cost adsorbent for HA removal for clean water production in peat land rural area.Â

Properties of Polyethersulfone Ultrafiltration Membrane by Incorporating Ionic Liquid for Humic Acid Removal

The present study was conducted to investigate the properties of fabricated polythersulfone ultrafiltration membrane by incorporating ionic liquid (IL) (Aliquat 336) in the casting solution towards HA removal. IL namely Aliquat 336 is used with varied composition of polyethersulfone (PES) as polymer and and Dimethyl acetamide (DMAC) as a solvent. All the fabricated membranes were characterized by Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), ganiometer and Thermogravimetric analysis (TGA) analysis. The fabricated membranes were also analyzed through its performance based on water flux, HA flux and HA rejection. The experimental results show that the incorporation of ionic liquid in different composition of polymer resulted in different characteristic of membrane and provided in improvement of HA removal. The P4 membrane gave the best performance with the water flux of 373.25 L/m2.h, the HA flux of 262.68 L/m2.h and the highest removal of HA up to 90%.

Metal organic framework UiO-66 incorporated ultrafiltration membranes for simultaneous natural organic matter and heavy metal ions removal

In this work, a new type of UiO-66 incorporated polysulfone (PSf) ultrafiltration (UF) membranes was fabricated to enhance antifouling properties and heavy metal ions removal efficiency. The UF membranes incorporating different loadings of the UiO-66 filler were prepared via the classical phase inversion process. These membranes unveiled enhanced hydrophilicity, porosity, water uptake, zeta potential, mechanical strength, permeability, and HA removal ratios due to the incorporation of hydrophilic UiO-66 fillers. Particularly, HA rejection ratios were observed to be approximately 93% for all the modified membranes, which was attributed to electrostatic repulsion interactions between the hydrophilic groups of HA and UiO-66. Moreover, the antifouling abilities of the modified membranes were evaluated and found to be much better with a high flux recovery ratio (FRR) of about 88% when compared to the blank PSf membrane (only around 34%). Moreover, the UiO-66 incorporated membranes were highly-effective in the removal of contaminants like heavy metal ions (Sr2+, Pb2+, Cd2+, and Cr6+) and HA at the same time. Overall, the PSf UF membranes incorporating UiO-66 opened up a new avenue to enhance the membrane hydrophilicity, permeability, antifouling properties as well as heavy metal ions removal abilities.

UV sensitive ZnO and TiO2‐ZnO nanocrystalline transparent glass‐ceramic materials for photocatalytic decontamination of surface water and textile industry wastewater

AbstractThe dispersion of pollutants in the aquatic environment is an emerging health concern worldwide. In this sense, it is essential to develop new materials that can improve the treatment quality of both water and wastewater. The present study has demonstrated evidence of the applicability of recyclable glass‐ceramic materials for the efficient photocatalytic treatment of real surface water and textile industry wastewater. Two glass compositions containing TiO2 or ZnO‐TiO2 have been investigated. The studied materials exhibited good performance in terms of humic acid and COD removal from raw surface water and textile industry wastewater, respectively. However, ZnO‐TiO2 glass‐ceramic photocatalyst was the best photocatalyst with maximum efficiency of 53% HA removal from surface water and 75% decolorization (or 60% COD removal) of wastewater. What is more, the reusability tests confirmed a minor variation (&lt;4%) in the photocatalytic efficacy for three consecutive usages. Therefore, the prepared materials are suitable for the applications in which reusability is an important key factor such as water and wastewater decontamination.

Preparation, characterization and coagulation performance of a composite coagulant: Polymeric aluminum ferric sulfate

Polymeric aluminum ferric sulfate (PAFS) was a novel inorganic composite coagulant, prepared by direct oxidation process using aluminum oxide (Al2O3) and ferrous sulfate heptahydrate (FeSO4⋅7H2O) as typical materials. In order to obtain the optimal removal rate of the turbidity and humic acid, the optimum preparation conditions of PAFS was investigated as follows: SO4 2-/Fe, NO3 −/Fe, PO4 3-/Fe, Al/Fe molar ratio and reaction temperature. The resultant polymer was characterized by scanning electron microscopytrans (SEM). The results showed that the optimum preparation conditions were SO42-/Fe of 0.35, Al/Fe of 0.11, NO3 −/Fe of 0.45, PO4 3-/Fe of 0.09 and reaction temperature of 80°C, and the maximum turbidity and HA removal efficiency could reach 98.4%, 93.5%, respectively.

The Preparation of Double Layers Low Pressure Carbon Nanotubes Membrane

Double layers low pressure carbon nanotubes (CNTs) membrane was prepared by pre-depositing CNTs on the Polyethersulfone (PES) flat membrane by pressure-assisted membrane filtration technology. Ethanol and Triton X-100 (TX-100) were used as dispersant to disperse two kinds of CNTs. By filtering two kind of CNTs dispersions in sequence, double layers CNTs were distributed on the surface of a PES membrane. With the proportion of the CNTs using TX-100 as dispersant increasing, the pure water flux of the double layers CNTs membrane will decrease. Normally, a membrane’s upper layer using ethanol as CNTs’ dispersant have higher pure water flux. Overall, almost all the double layers low pressure CNTs membrane realized the higher HA removal rate than single layer. By using CNTs with a diameter of 10-20 nm and length of 10-30 μm, the membrane with upper layer of 70% CNTs using ethanol as dispersant and 30% CNTs using TX-100 as dispersant can removal over 95% HA.

Removal of humic acid from aqueous solution by Fe3O4@L-arginine magnetic nanoparticle: kinetic and equilibrium studies

ABSTRACT Natural organic materials, principally humic acids cause serious problems in water treatment plants due to combination with chlorine and the formation of carcinogenic disinfection by-products. In the present study, the Fe3O4@L-arginine magnetic nanoparticle was synthesised and used to adsorbhumic acid (HA) from the aqueous solution. Fe3O4@L-arginine nanoparticles were prepared withthe co-precipitation method and characterised by FE-SEM, FTIR, XRD, and zeta potential analysis. The effect of different parameters on the HA removal by Fe3O4@L-arginine was investigated. The results showed that by increasing the adsorbent dose, contact time and temperature, the efficiency of HA removal increased, but by increasing theinitial concentration of HA, ionic strength, and pH, the efficiency of HA elimination decreased. Under optimal conditions, the highest HA removal efficiency in 0.5 g/L and 2 g/L adsorbent doses was found to be 67.23% and 96.4%, respectively. Also, the study of isotherm and kinetic of adsorption showed that the adsorption of HA on Fe3O4@L-arginine followed Langmuir isotherm and pseudo-second-order kinetic.Adsorption experiments demonstrated that Fe3O4@L-arginine as an effective and reusable adsorbent has a good capacity for the removal of HA from aqueous solution.

Improving the efficacy of PES-based mixed matrix membranes incorporated with citric acid–amylose-modified MWCNTs for HA removal from water

Either difficulty of dispersion of carbon nanotubes (CNTs) in the solvent or low compatibility between polymeric chains of membrane and CNTs results in major drawbacks to using CNTs in the structure of mixed matrix membranes. CNTs’ functionalization has already gained increasing attention to overcome such problems. Herein, polyethersulfone-based mixed matrix membranes incorporated with citric acid–amylose-decorated multiwall carbon nanotubes (Am–MWCNTs–CA) were fabricated. These new synthesized nanoparticles and nanocomposite membranes were characterized by spectroscopic measurement methods such as IR spectroscopy, UV–Vis spectroscopy, 1H NMR spectroscopy, 13C NMR spectroscopy, water contact angle, attenuated total reflection-infrared, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The pure water flux of the modified membrane incorporated with 0.5 w/v% Am–MWCNTs–CA increased over 130% in comparison with the unmodified membrane. Flux recovery ratio results illustrated that the membrane modified with 0.5 w/v% Am–MWCNTs–CA showed superior antifouling capacity of over 95.2%. SEM and AFM images showed significant and observable changes in surface morphology along with the formation of large finger-like macrovoids in the presence of Am–MWCNTs–CA. The presence of more COOH and OH functional groups on the surface of the modified membranes enforced the Donnan exclusion theory to reject rather divalent ions due to the migration of Am–MWCNTs–CA nanocomposite to the surface of membranes. In addition, humic acid removal capability of the prepared membranes was also calculated to be as high as 97.4% for the membrane embedded with 0.5 w/v% Am–MWCNTs–CA (M3).

NOM (HA and FA) Reduction in Water Using Nano Titanium Dioxide Photocatalysts (P25 and P90) and Membranes

This study examined the removal of natural organic substances (humic acids-HA, and fulvic acids-FA) from model solutions using photocatalysis and ultrafiltration. The effect of two nano titanium dioxide types (P25 and P90) with different active surface areas and two UV lamps (low-pressure and medium-pressure) on the effectiveness of FA and HA removal during photocatalysis was tested. An integrated photocatalytic + ultrafiltration system was also analyzed to determine the effectiveness of FA and HA removal and the changes in the relative permeate flux (Ultrafiltration Membrane Fouling-UF). We observed that photocatalysis using the P90 nano titanium dioxide was more efficient than the P25 due to the larger surface area (2×). The decomposition of organic substances proceeded efficiently up to 30 min of solution exposure, and the use of a medium-pressure lamp accelerated compound decomposition relative to the low-pressure lamp. The applied photocatalysis + ultrafiltration system was characterized by a high degree of FA removal while improved hydraulic efficiency was observed during ultrafiltration.

Application of amine-functioned Fe3O4 nanoparticles with HPEI for effective humic acid removal from aqueous solution: Modeling and optimization

Humic acids are one type of natural organic matter and precursors of chloro organic compounds that cause a major problematic issue for water treatment plants. In the present study, Hyperbranched polyethylenimine (HPEI) was grafted onto Fe3O4 nanoparticles for HA adsorption from aqueous solution. Fe3O4@HPEI nanoparticles were characterized via TEM, SEM, FTIR, XRD, VSM, and BET analysis. The effects of various operational parameters including initial HA concentration, pH, adsorbent dose, contact time and ionic strength on the HA removal were assessed. According to the obtained statistical model, the optimal condition was acquired at the initial HA concentration 79 mg/L, adsorbent dose 0.128 g/L, pH 3 and contact time 29 min, which up to 97.27% HA were adsorbed by Fe3O4@HPEI that was close to the predicted result by the model (95.6%) that confirmed the validity of the selected model. The adsorption data were fitted to the pseudo-second-order kinetic and Freundlich isotherm. Thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic. The fabricated Fe3O4@HPEI nanoparticles could be repeatedly utilized as a suitable adsorbent to remove HA from the aqueous environment.

Elimination of humic acid in water: comparison of UV/PDS and UV/PMS.

Humic substances are polyelectrolytic macromolecules; their presence in water leads to many environmental problems without effective treatment. In this work, the elimination of humic acid (HA), a typical humic substance, has been examined through ultraviolet (UV) activation systems in the presence of peroxydisulfate (PDS) and peroxymonosulfate (PMS), respectively. The results indicated that 92.9% and 97.1% of HA were eliminated with rate constants of 0.0328 ± 0.0006 and 0.0436 ± 0.0011 min−1 with 180 and 60 min treatment times at pH 6 and 3 when adding 3 and 1 mmol L−1 oxidant during UV/PDS and UV/PMS, respectively; the corresponding electric energies per order were 0.0287 and 0.0131 kW h m−3. The HA removal was systematically investigated by varying different reaction parameters, including radical scavengers, persulphate dose, solution pH, and initial HA concentration, and by addition of various common ions. Moreover, the decomposition details were identified through the changes in the dissolved organic carbon, unique UV absorbances, and UV spectroscopic ratios. Furthermore, the destruction mechanism was verified by fluorescence spectroscopy, demonstrating that the HA structure was decomposed to small molecular fractions in the two UV/persulphate systems. In addition, the purification of HA by the two UV/persulphate processes was assessed in actual water matrices.

High-poly-aluminum chloride sulfate coagulants and their coagulation performances for removal of humic acid.

High-poly-aluminum chloride sulfate (HPACS) coagulants with different [SO42−]/[Al3+] molar ratio (S) were prepared and proved to have high coagulation efficiency for the removal of humic acid and strong stability for storage and application. The results showed that the higher the SO42− addition, the bigger the aluminum polymerization particles and the more the polymerization Alc existed in the prepared HPACS coagulants. The HPACS exhibited higher coagulation efficiency, a better aging stability and stronger resistance to the change of pH and Ca2+ concentration of raw water than the polyaluminum chloride (PAC) and poly-aluminum chloride sulfate (PACS) reported before. The Sips adsorption neutralization model was established to illustrate the relationship between coagulant dosage and zeta potential of the water system. The adsorption neutralization capacity was proved to be HPACS (S = 0) > HPACS (S = 0.02) > HPACS (S = 0.06) > HPACS (S = 0.10), which was not completely consistent with the coagulation effect of HPACS with different S values and indicated that in addition to adsorption neutralization, actions like bridge-aggregation, precipitation, and sweep-flocculation also played an important role during HPACS coagulation. Moreover, the negative Gibbs free energy indicated that the coagulant adsorption neutralization reaction was a spontaneous process.

Purification Efficiency and Mechanism of Integrated Al Salt Floc-ultrafiltration Membrane Process

Owing to the small land use and high pollutant removal efficiency, the integrated ultrafiltration (UF) membrane process has been gradually applied in water treatment. However, not only would the membrane surface be damaged by the commonly used granular adsorbents over time, but these types of adsorbents are expensive, such as nano zerovalent iron, carbon nanotubes, etc. To overcome these disadvantages, the loose Al-based flocs were directly injected into the membrane tank in the presence of humic acid and Miyun reservoir water. Results showed that severe membrane fouling was induced by HA alone, and the transmembrane pressure (TMP) significantly increased to 76.4 kPa after 12 d of operation. However, it dramatically decreased to 10.1 kPa after washing with tap water on day 13, indicating that the cake layer was the main fouling mechanism. The average HA removal efficiency was only 23.3% during filtration. In addition, the performance of the integrated flocs-membrane process could be influenced by floc dosage, injection frequency, and solution pH. The integrated membrane performed well with flocs (43.2 mmol·L-1) continuously injected at pH 6.0 (aeration rate at 0.3 L·min-1). The corresponding TMP only increased to 19.5 kPa after running for 12 d, which decreased to 5.6 kPa after washing with tap water on day 13. The average HA removal efficiency increased to 61.2%. Additionally, serious membrane fouling was also induced by Miyun reservoir alone. The TMP increased to 38.0 kPa on day 12, while it decreased to 3.8 kPa after washing with tap water on day 13. The cake layer was also the main fouling mechanism, and the average pollutant removal efficiency was only 7.5%. With floc continuously injected, however, the TMP only increased to 6.1 kPa on day 12. After washing with tap water, the TMP decreased to 2.3 kPa on day 13, and the average pollutant removal efficiency was as high as 58.6%. Based on the excellent membrane performance, the integrated membrane process exhibited potential application in drinking water treatment.

Abstract 2740: PEGylated recombinant hyaluronidase PH20 (pegvorhyaluronidase alfa PEGPH20) converts HA-rich tumors from resistant to sensitive to anti-PD-L1 immunotherapy in murine syngeneic breast cancer models

Abstract Hyaluronan (HA) is an extracellular glycosaminoglycan that accumulates in the tumor microenvironment (TME) of many solid tumors. In preclinical studies, enzymatic degradation of TME HA by intravenous PEGylated recombinant human hyaluronidase PH20 (PEGPH20) remodels the TME, reduces tumor interstitial fluid pressure, decompresses tumor blood vessels, and facilitates delivery of chemotherapeutics. PEGPH20-mediated HA degradation increases anti-PD-L1 efficacy in HA-rich EMT-6 tumors and enhances CD8+ T-cell infiltration in tumors. Cancer patients can be resistant to anti-PD-L1; strategies to increase T cell infiltration may lead to anti-PD-L1 effectiveness in nonresponders. We hypothesized that PEGPH20 may convert HA-rich tumors with low T cell infiltration from resistant to sensitive to anti-PD-L1 immunotherapy. 4T1 breast cancer cells transduced with HAS3 to generate HA-rich 4T1/HAS3 cells averaged ~2.9×104 CD8+ T cell/g tumor on day 18 post-tumor inoculation and were resistant to anti-PD-L1 monotherapy. PEGPH20 treatment of 4T1/HAS3 tumors significantly increased CD8+ T cell infiltration to ~7.2×104/g tumor (p=0.0007) and 4T1/HAS3 tumors became sensitive to anti-PD-L1 treatment. PEGPH20 + anti-PD-L1 led to 64.0% tumor growth inhibition (TGI; p&amp;lt;0.0001 vs vehicle + isotype antibody [IgG2b]) vs PEGPH20 alone (10.7% TGI) or anti-PD-L1 alone (-5.1% TGI). PEGPH20 significantly increased infiltration of CD4+ T cells and NK cells, and decreased the percentage of CD11b+GR1+ myeloid derived suppressive cells among CD45+ cells, vs vehicle + IgG2b in 4T1/HAS3 tumors. EMT-6 tumors were sensitive to anti-PD-L1 when starting tumor size was small (~133 mm3) but became resistant with larger starting tumor size (~325 mm3). PEGPH20 + anti-PD-L1 converted larger EMT-6 tumors to sensitive to anti-PD-L1 with 64.9% TGI (p=0.049 vs vehicle + IgG2b), whereas neither PEGPH20 alone nor anti-PD-L1 alone significantly inhibited tumor growth. Small EMT-6 tumors (~136 mm3) were resistant to a lower dose of anti-PD-L1; however, PEGPH20 + low-dose anti-PD-L1 converted EMT-6 tumors from resistant to sensitive to low-dose anti-PD-L1 (65.4% TGI, p&amp;lt;0.0001 vs vehicle + IgG2b). Imaging studies using fluorescence-labeled anti-PD-L1 antibody showed PEGPH20 enhanced the accumulation of anti-PD-L1 in TME. Our data suggest that PEGPH20-mediated HA removal increases infiltration of lymphocytes and immunotherapeutic antibody accumulation in HA-rich tumors. PEGPH20 converts HA-rich tumors from resistant to sensitive to anti-PD-L1. Clinical trials are ongoing to evaluate PEGPH20 + anti-PD-L1 in patients with cholangiocarcinoma/gallbladder cancer (NCT03267940) and gastric cancer (NCT03281369), and to evaluate PEGPH20 + anti-PD-1 in patients with non-small cell lung cancer and gastric cancer (NCT02563548). Citation Format: Renee Clift, Xiaoming Li, Barbara Blouw, Curtis B. Thompson, Yujun Huang. PEGylated recombinant hyaluronidase PH20 (pegvorhyaluronidase alfa PEGPH20) converts HA-rich tumors from resistant to sensitive to anti-PD-L1 immunotherapy in murine syngeneic breast cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2740.