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To effectively evaluate the level of economic security of water resources (WES) in China and analyze its influencing factors, a comprehensive evaluation model of WES and a regression analysis model of influencing factors are established based on the panel data of 30 provinces in China from 2011 to 2017. It is found that, first, WES in China presents a fluctuating upward trend. Second, different regions have different economic security levels for their water resources in China, among which WES in the central region is the highest. Third, there is a U-shaped correlation between economic development and WES, and the population, pollution control level, technological innovation have negative impacts on WES. Moreover, this study also finds that with upgrades to the industrial structure and level of human capital, there will be improvements to WES. However, the external coefficient and the investment scale of fixed assets have a negative impact on the economic security of water resources. This is helpful to utilize the water resources, and improve the water resources safety management.

With the development of industrial technology, heat transfer at the microscale has attracted more and more attention. In this work, 200 µm platinum wire and 150 µm nickel-chromium wire were used as experimental objects, which the power was provided by DC power with the range of 15.6 W to 56.2 W. Distilled water was used as the experimental liquid. Various bubbles on the micro wire were observed and the heat mechanism was analyzed. A variety of bubble attachment phenomena were captured on the 200 µm platinum wire, including the adhesion during bubble detachment, the rotation of small attached bubbles on the surface of large bubble, multiple bubbles circling at the top of the same bubble, and different attached bubble departure phenomena. Marangoni force in the vertical direction triggered the formation of bubble attachment. In addition, the effects of surface tension, adhesion force and buoyancy force on the circling of the bubble were also considered. The analysis of the bubble sweeping on the 150 µm nickel-chromium wire was analyzed. The results showed that the static bubble would interact with the sweeping bubbles on the other side, thereby changing the heat transfer mechanism, which was not discussed in detail before. The bubble jet flow generated by thermocapillary convection on the vertical direction of the bubble surface was the main influencing factor, which would change the microlayer encountered in front of the bubble. The effects of bubble diameter and liquid subcooling on the sweeping velocity were also studied. The results showed that the larger the bubble diameter was, the lower the sweeping velocity would be achieved while the liquid subcooling temperature had less impact on the velocity of sweeping bubble.

Technology innovation is the key driving force in achieving economic transformation and development. Financial development and the expansion of higher education can promote technological progress primarily by easing financing constraints and improving the level of human capital. This study examines the impact of financial development and higher education expansion on green technology innovation. It conducts an empirical analysis by constructing a linear panel model and a nonlinear threshold model. The present study sample is based on the urban panel data of China from 2003–2019. (1) Financial development can significantly promote the expansion of higher education. (2) The expansion of higher education can improve energy and environment-based technological progress. (3) Financial development can both directly and indirectly promote green technology evolution by expanding higher education. The joint financial development and higher education expansion can significantly empower green technology innovation. (4) In the process of promoting green technology innovation, financial development has a non-linear influence on it, with higher education as the threshold. The effect of financial development on green technology innovation varies according to the degree of higher education. Based on these findings, we put forward policy proposals for green technology innovation to promote economic transformation and development in China.

Micro (nano)plastics pollution is a noxious menace not only for mankind but also for marine life, as removing microplastics (MPs) is challenging due to their physiochemical properties, composition, and response toward salinity and pH. This review provides a detailed assessment of the MPs pollution in different water types, environmental implications, and corresponding treatment strategies. With the advancement in nanotechnology, mitigation strategies for aqueous pollution are seen, especially due to the fabrication of nanosheets/membranes mostly utilized as a filtration process. Two-dimensional (2D) materials are increasingly used for membranes due to their diverse structure, affinity, cost-effectiveness, and, most importantly, removal efficiency. The popular 2D materials used for membrane-based organic and inorganic pollutants from water mainly include graphene and MXenes however their effectiveness for MPs removal is still in its infancy. Albeit, the available literature asserts a 70- 99% success rate in micro/nano plastics removal achieved through membranes fabricated via graphene oxide (GO), reduced graphene oxide (rGO) and MXene membranes. This review examined existing membrane separation strategies for MPs removal, focusing on the structural properties of 2D materials, composite, and how they adsorb pollutants and underlying physicochemical mechanisms. Since MPs and other contaminants commonly coexist in the natural environment, a brief examination of the response of 2D membranes to MPs removal was also conducted. In addition, the influencing factors regulate MPs removal performance of membranes by impacting their two main operating routes (filtration and adsorption). Finally, significant limitations, research gaps, and future prospects of 2D material-based membranes for effectively removing MPs are also proposed. The conclusion is that the success of 2D material is strongly linked to the types, size of MPs, and characteristics of aqueous media. Future perspectives talk about the problems that need to be solved to get 2D material-based membranes out of the lab and onto the market.

Oxygen-rich combustion is a new type of clean combustion technology with important application prospects. In this work, the effects of oxygen-rich combustion on soot formation in the propane/(O2+N2) laminar flow coaxial jets diffusion flame were numerically investigated by using the detailed gas-phase chemical reaction model with the mechanism of tetracyclic aromatic hydrocarbons and the complex thermodynamic properties and transport characteristics parameters. Soot surface growth follows the hydrogen-abstraction-carbon-addition (HACA) model. A hybrid gas-phase mechanism was adopted, which contains a DLR-based polycyclic aromatic hydrocarbons (PAHs) formation, growth model and a gas-phase model. Results show that the oxygen-rich combustion has a great influence on the flame temperature, especially the high temperature region. With the increase of oxygen concentration, the soot formation region of flame broadens and the maximum of soot volume fraction increase from 3.95 ppm to 10.87 ppm. The extra oxygen makes PAHs increased around the nozzle, leading to larger rate in early soot nucleation and surface growth, eventually more soot yield.

Microplastics (MPs) implications in the atmosphere are of current global concern. Currently, there is a growing interest regarding source appointment, fate, level of toxicity, and exposure intensity of ambient air MPs. Recent data suggest that polyethylene (PE) dominates ambient MPs in China's megacities. Albeit understanding of PE sources is limited and restricted to typical sources polluting terrestrial and marine environments. However, the air is a distinct environmental component and may have some separate pollution sources as well as the relative contribution of different sources could also contrast in different environments. Urbanization and fast construction activity resulting from increased economic growth in these places might be a potential source of ambient PE. Recently, the use of scaffold netting on construction sites and synthetic grass as land covering sheets has been on the rise. Generally, these PE items are often inferior and composed of recycled material, making them more prone to degradation. Also, because these items were continually exposed to open air, there is a considerable risk of fragmentation and atmospheric mixing. Therefore, unchecked and excessive usage of these materials can be risky. Here, PE's physical and chemical characteristics, transport and health risks in urban air are discussed here.

Advances in urban infrastructure, a flourishing polymer sector, and more traffic have all contributed to a rise in micro(nano)plastics in the environment. Researchers are exploring the production, fate, toxicity threshold, and severity of micro(nano)plastic exposure. Albeit, understanding sampling protocols, preservation of samples, and characterization of micro(nano)plastics obtained from the different mediums (e.g., soil, water, air, and living bodies) is still challenging. Particularly identification of micro(nano)plastics, on the other hand, is restricted and limited to the typical generic definition of contaminating sources. In addition, before micro(nano)plastics degrade naturally, many challenges must be overcome, enhancing the need for research on assisted degradation. Thus, a systematic review is presented, which begins by discussing micro(nano)plastic identification, sampling, and handling; then showcases the environmental and health consequences and how to control them; finally, it discusses environmental micro(nano)plastics management options. According to studies, biological and chemical methods to break down micro(nano)plastics have risen in popularity. However, these methods often only cover one type of plastic. Furthermore, these solutions can transform polymers into micro(nano)plastics and may also produce byproducts, increasing environmental contamination risk. Therefore, control, prevention, and management strategies are all investigated to generate more realistic and long-term solutions. The literature suggests a combination of different microorganisms (e.g., different bacterial species) and different approaches (e.g., filtration with degradation) could be more effective in the treatment of micro(nano)plastics. Furthermore, according to the literature, relevant health risks associated with micro(nano)plastics to humans from various exposure routes are currently unclear. Likewise, standardization of methods supported with sophisticated state-of-the-art apparatus for detecting micro(nano)plastics is required. Overall, precision in micro(nano)plastic identification and treatment strategy selection is critical, and their usage should be regulated if their environmental behavior is not properly addressed.

Recently, biodegradable plastics (BPs) as an alternative of conventional plastics have been widely advocated and applied. However, there is still a large research gap between the formation of secondary microplastics (MPs) and colonized microorganisms on their surface under long-term aging in different environments. In this study, the generation of secondary MPs and the formation of surface biofilms on the micro-sized (3-5 mm) biodegradable plastic poly (butyleneadipate-co-terephthalate) (BP-PBAT) and conventional plastic polyvinyl chloride (CP-PVC) under long-term UV aging was investigated. The results showed that hundreds and even thousands of MPs (185.53 ± 85.73 items/g - 1473.27 ± 143.67 items/g) were generated by BP-PBAT and CP-PVC after aged for 90 days, and the abundance of MPs produced by BP-PBAT was significantly higher than that of CP-PVC. Moreover, the α diversities and detected OTU number of biofilm communities formed on MPs increased with MPs-aging. The genes related to the formation of biofilms was significantly expressed on aged MPs and the genes related to human pathogens and diseases were also detected in enriching on MPs surface. Overall, BPs may lead to greater ecological risks as it releases thousands of secondary MPs after being aged, and their environmental behavior needs to be further explored.

The shortage of fossil fuels is actually a major economic issue in the context of increasing energy demand. Renewable energies are thus gaining in importance. For instance, microalgae-based fuels are viewed as an alternative. Microalgae are microscopic unicellular plants, which typically grow in marine and freshwater environments. They are fast growing, have high photosynthetic efficiency, and have relatively small land requirement and water consumption in comparison with conventional land crops biofuels. Nonetheless, selling biofuels is still limited by high cost. Here, we review biofuel production from microalgae, including cultivation, harvesting, drying, extraction and conversion of microalgal lipids. Cost issues may be solved by upstream and downstream measures: (1) upstream measures, in which highly productive strains are obtained by strain selection, genetic engineering and metabolic engineering, and (2) downstream measures, in which high biofuels yields are obtained by enhancing the cellular lipid content and by advanced conversion of microalgal biomass to biofuels. Maximum biomass and high biofuels production can be achieved by two-stage culture strategies, which is a win–win approach because it solves the conflicts between cell growth and biomass accumulation.

The use of biodegradable plastics (BPs) has been widely promoted in recent years, but before their complete degradation, the phase of microplastics (MPs) is inevitable. However, little information concerning the production of MPs from blended polymers is available. This study aimed to explore the characteristics of MPs produced from blended plastics and the development of biofilms on plastic surfaces under long-term aging. Here, three blended materials (i.e., PBAT (53%)+PLA (10%)+Starch (20%), PBAT (80%)+Starch (20%), HDPE (60%)+CaCO

Although microplastics (MPs) are known to be found in global oceans, their influencing factors and abundance in the deep sea remain largely unknown. Twenty-six surface sediment samples were collected in the deep basin of the Eastern Indian Ocean (EIO). This study showed that MPs abundance ranged from 30.30 particles/kg to 701.7 particles/kg, with an average of 170.5 ± 140.2 particles/kg. The MPs found in the sediment of the EIO mainly contain fragments and fibers, which account for 47.5% and 45.6%. The MPs were measured in a size range of 44-5000 μm, and the most frequently detected MPs in size of 200-500 μm. MPs were in various compositions, but most of them were found in rayon (62.2%) and polyester (25.7%). The spatial distribution of MPs in the sediments shows a decreasing trend from nearshore to the open sea. In the Bay of Bengal (BOB) and the coast of Sri Lanka (COSL), the abundance of MPs was relatively high, indicating that the spatial distribution of MPs is affected by land source input, river input, and anthropogenic activities. Principal component analysis indicated daily commodities and packaging applications/fishing accounted for 36.9% and 12.9% of the MPs occurrence in the EIO, respectively. Average MPs diversity indices for the BOB (0.87 ± 0.38), the COSL (0.64 ± 0.56), and the Eastern Indian Ocean Basin (EIOB) (0.60 ± 0.24) revealed the BOB had the most complicated MPs sources. In addition, we found that the abundance of MPs has no significant effect on organic carbon and sediment grain size. This study is the first report of MPs detection in the deep-sea sediment in the EIO and can provide a baseline of MPs pollution in this area.

Laminar diffusion flame was used to study the effect of ethanol on n-heptane flame in terms of the morphology and microstructure of soot under atomization combustion. For the same carbon mass flux at the outlet of the burner, the ratio of ethanol doping in n-heptane was changed, and the soot was collected from the axial positions of the flame at different heights using the thermophoresis probe method. The results showed that the flame height increased significantly with the increasing ratio of ethanol doping. When the ratio of ethanol and n-heptane (CE/CN) was 1.5, the flame height increased by 10 mm compared with that of pure n-heptane flame. Besides, the temperature in the center of the flame decreased with the increasing ratio of ethanol doping, but the temperature in the low position was higher than that in the pure n-heptane flame, and the temperature in the high position was lower than that in the pure n-heptane flame. However, the flame temperature was the highest when the proportion of ethanol in the mixture was greater than that of n-heptane. The temperature at the flame center decreased with the increasing ratio of ethanol doping, while the temperature at the flame edge increased with the ratio. The primary particle size of soot (soot size hereafter) in all working conditions increased with the increase of flame height, which was in line with the general growth law of soot. Moreover, the soot size at the same height decreased with the increasing ratio of ethanol doping, and this trend was most obvious at the flame height of 20 mm and 30 mm. Compared with pure n-heptane, when CE/CN was 1.5, the soot size at 20 mm and 30 mm decreased by an average of 34.83%, indicating that ethanol could inhibit the surface growth of soot particle. Furthermore, the density of soot particles collected by a single copper net decreased significantly, indicating that ethanol could reduce the production amount of soot.

In this study, the distribution, abundance, morphology, and composition of microplastics (MPs) in surface seawater and sediment of Hainan Island were systematically investigated. Seawater and sediment samples were collected from six functional zones, including harbor, industrial district, sparsely populated area, tourist area, residential area, and aquaculture area. The abundance of MPs in seawater was 0.46-19.32 items/L, with an average of 2.59 ± 0.43 items/L, which were similar to those detected in the South China Sea (e.g., Nansha (1.25-3.20 items/L) and Xisha (2.57 ± 1.78 items/L)). The highest level was detected in Qinglan Bay Estuary, and the lowest was in Sanya West Island. The abundance of MPs in sediment was 41.18-750.63 items/kg, with an average of 372.47 ± 62.10 items/kg; the highest concentration was detected at Tanmen Port, and the lowest was in Lingao sea area. It was detected that the MPs with smaller size exhibited a higher concentration in seawater. MPs were commonly black and white, and predominantly linear and fragmented in shape. Polyethylene terephthalate (PET) was the dominant polymer, which might be derived from laundry wastewater. The petroleum concentration was 0.02-0.21 mg/L in the investigated area, with harbors being the most severely polluted areas. Furthermore, this study also found that MPs pollution was positively correlated with petroleum in seawater, indicating similarities between MPs and petroleum-based sources of pollution. This study identifies the contamination and characteristics of MPs and their correlation with petroleum in Hainan Island, the biggest island in the South China Sea, providing important data for further research on protecting marine ecosystems.

Microplastics (MPs;5 mm) and oil pollution have been receiving global attention. To date, the adsorption mechanism of petroleum by MPs is largely unknown. This study investigated the adsorption of petroleum on micro-sized polyethylene (mPE) undergoing aging (days 0, 15, 30, 90 and 180). The petroleum adsorption capacity of mPE was further assessed at varying pH (2, 5, 7.32, 10 and 12), temperature (4, 15, 25, 45 and 65 °C) and in presence of coexisting pollutants (Cu, bisphenol A (BPA) and petroleum). The results indicated that the adsorption capacity of mPE increased with the prolonged aging time and smaller-sized particles, while the adsorption capacity of the 550 and 165 μm mPE undergoing aging increased by 12.7%-50.9% and 22.1%-63.9%, respectively. The adsorption kinetics and isotherm model of mPE on petroleum were well fitted by pseudo-second order, intraparticle diffusion, Freundlich and Langmuir models, showing the sorption behavior was controlled by the diffusion of pores, liquid film diffusion, and surface adsorption. The petroleum adsorption capacity of mPE was predominant affected by surface roughness, specific surface area, hydrophobicity, oxidation functional groups, adsorption sites, hydrogen bonds, while zeta potential and crystallinity may not be the crucial factors. Likewise, temperature and pH may influence the characteristics of petroleum, and further result in a decreasing adsorption capacity of mPE to petroleum. The highest adsorption capacity of mPE to petroleum was reached at pH 7.32 and 25 °C. The coexisting Cu, BPA and petroleum competed for adsorption sites on the surface of mPE. These findings could fundamentally provide new insights for environmental risk assessment of MPs, particularly for the specific location like harbor which is commonly rich in MPs and petroleum simultaneously.

The implementation of Industry 4.0 has had an important impact on the value creation of the manufacturing industry, but there are few studies on its driving mechanisms and effect on total factor productivity. In this study, green technology progress is selected as an important representation of Industry 4.0, and samples of China's A-share resource-based enterprises from 2004 to 2018 are used to examine the relationship between environmental regulation, green technology progress, and total factor productivity to explore the role of social, environmental, and technological factors in manufacturing development. The findings show that green technology progress significantly promotes the total factor productivity of enterprises through the improvement of unit labor productivity and that environmental regulation “forces” the green technology progress of enterprises through external pressure. These conclusions remain valid after replacing the explained variables and measuring methods. The results of heterogeneity analysis show that when an enterprise has strong financial and human resource bases, the “forcing” effect of environmental regulation on green technology progress is more significant.

To date, the degradation of microplastics (MPs;5 mm) in different environments, particularly their adsorption characteristics for coexisted metal pollutants remains to be elucidated. Thus, this study investigated the effects of aging MPs, including polyamide (mPA), polyethylene terephthalate (mPET), polystyrene (mPS), and polyvinyl chloride (mPVC) for 3 months under UVA irradiation in four environmental media (air, seawater, sand, and soil) and adsorption of heavy metals (Cu, Cd) onto seawater-aged mPS and mPVC. The results showed that surface morphological changes, including cracks, oxidized particles, and wrinkles, appeared on aged MPs. The heavy metal adsorption capacity decreased in the order aged mPVCaged mPS unaged mPS unaged mPVC, and the Cu

Microplastics (MPs) pollution has been increasingly investigated in marine and freshwater environments, even in atmosphere in China. Current literatures show that MPs contamination is highly related to human activities and geomorphology. Higher MPs occurrences were detected in freshwaters than those in seawaters in China. Furthermore, the abundance of MPs was influenced by many factors, including sampling method, unit of measurement, characteristics of sampling area, and others. Currently, investigating the condition of MPs occurrences and distribution on a broader scale and developing standardized protocol, along with basic toxicological research, will help to address crucial knowledge gaps regarding MPs pollution, their interaction with other pollutants and ecological consequences on individual, population or ecosystem levels in the environment. Meanwhile, this review calls for more efforts to be made for better and scientifically sound risk management for mitigation of MPs pollution in China.

Plastic litters have become the predominant components of marine debris due to extensive consumption plastics and mismanagement of plastic wastes. As part of the problem, microplastics (MPs) and nanoplastics (NPs) have generated special concerns due to their unique features that make them easy to transfer among oceans in the marine ecosystem, across different trophic levels inside the food web, and even across different tissues inside contaminated animals. Studies have demonstrated the almost omnipresence of MPs in the marine ecosystem, which present serious threats to the health of marine animals, causing symptoms such as malnutrition, inflammation, chemical poisoning, growth thwarting, decrease of fecundity, and death due to damages at individual, organ, tissue, cell, and molecule levels. The information on NPs in the marine ecosystem has been scarce due to the challenges in sampling and detecting these nano-scaled entities. In vitro and in vivo experiments have demonstrated that NPs have the potential to penetrate different biological barriers including the gastrointestinal barrier and the brain blood barrier and have been detected in many important organs such as brains, the circulation system and livers of sampled animals.

This study investigated the deleterious effects of oxygen stress in a range of 100–400 % air saturation and verified the alleviation effects of the addition of bicarbonate and adjustment of culture pH. In the cultures with imposed dissolved oxygen (dO2) stress at 400 % air saturation, the highest dry cell weight (DCWmax) of 1.04 ± 0.17 g L−1, lipid content (LC) of 151.2 ± 4.8 mg g−1 DCW and lipid productivity (LP) of 19.1 ± 0.8 mg L−1 day−1 were obtained in the cultures supplemented with 160 mM NaHCO3, compared to a DCWmax of 0.76 ± 0.018 g L−1, LC of 116.3 ± 0.2 mg g−1 DCW and LP of 9.96 ± 0.02 mg L−1 day−1 in the control (with 0 mM NaHCO3). The results indicate that oxygen stress was hazardous to cell growth and impaired lipid accumulation in Neochloris oleoabundans. The addition of bicarbonate alleviated oxygen stress through increasing the ratio of dCO2 to dO2 to balance the photosynthesis and photorespiration, inhibiting the production of reactive oxygen species (ROS) and activating cellular antioxidant mechanisms such as enhanced lipids as an electron sink and ROS-scavenging antioxidant enzymes. Studies also show that the increase of pH in the range of 7.5–9.5 enhanced cell growth and lipid accumulation, although accompanied by increasing ROS concentration in cultures.

This study evaluated long-term non-sterile cultivation of freshwater green alga Neochloris oleoabundans in a 15-liter bubble column photobioreactor (BCPBR) and the effects of a membrane-based localized oxygen remover (LOR) on deoxygenation, cell growth, and lipid production of N. oleoabundans. Batch and continuous cultivations were carried out under non-sterile conditions for 53 days with no detectable protozoa or other biological contaminants, indicating successful long-term contamination-free cultivation. The results show that the BCPBR equipped with LOR (BCPBR-LOR) has enhanced deoxygenation efficiency and were able to maintain dissolved oxygen at a level of around 120% air saturation, which was 32% lower than that of the conventional BCPBR, which had no LOR. While similar biomass concentration and productivity were obtained in both systems, significantly higher lipid cell content and lipid productivity of microalgae were obtained in the latter, which was attributed to the low dO2 in culture due to enhanced deoxygenation efficiency of BCPBR-LOR.

This study investigated microplastics (MPs) pollution in Haikou Bay in the northern South China Sea (SCS). Eight sampling sites were selected on the basis of their functions as hotel-intensive areas, public beaches, harbors, municipal discharge sites, and public waters. A total of 1053 putative plastic particles of which 1019 were from seawater and 34 from sediment were collected using 333 μm nylon Neuston nets and a bottom collector, respectively. The results showed that the abundance of MPs ranged from 0.26 to 0.84 items/m3 (hereafter defined as n/m3) in the surface water and 0.66 ± 0.58 n/50 g (d.w.)–17.00 ± 6.56 n/50 g (d.w.) in the sediment of Haikou Bay. For the surface seawater samples, the predominant MPs were fibers (83.12%) in rayon (52.73%). For the sediment samples, MPs were predominantly in fibers (67.65%), while PE (28.41%), polyolefin (25.50%), rayon (23.53%) were frequently detected. MPs are widely found in coastal seawater and sediment, but with different abundance in different functional areas. A higher abundance of MPs was found in the seawaters of public beaches and sediments of sewage discharge ditches. Our results highlight the occurrence of MPs in Haikou Bay, and we also offer field study results for the evaluation of environmental risks posed by MPs in the northern SCS.

Large quantity of oxygen evolves as a byproduct of photosynthesis in microalga cultivation. As a result, dissolved oxygen of 100–400% air saturation or even higher is commonly observed in microalgal cultures. High concentration of dissolved oxygen may inhibit photosynthesis, cause photochemical damages to photosynthetic apparatus and other cellular components, result in reduction of cell growth or even culture collapse. Effective deoxygenation mechanisms are required to maintain dissolved oxygen at a level that is not inhibitory. This remains a significant challenge despite of the enormous technical advances in this field and information on large scale photobioreactors are scarce, which warrants systematic future studies, especially with controlled large-scale systems, in this important field. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 982–988, 2013

Coal fly ash is a solid waste generated in large amounts worldwide; therefore, development of new techniques for its productive reuse is important. Two zeolites synthesized from coal fly ashes (ZFAs) were prepared and then modified using hexadecyltrimethylammonium (HDTMA). Both ZFAs and surfactant modified ZFAs (SMZFAs) were investigated for their ability to adsorb humic acid (HA) from water. The results indicated that, while ZFA had little affinity for HA, SMZFA showed greatly enhanced adsorption capacity. The adsorption isotherm was well fitted to the Langmuir model. The uptake of HA was substantially influenced by pH, increasing under acidic pH conditions. The SMZFA, which had a higher BET area and higher amount of loaded HDTMA, showed greater retention of HA. Uptake of HA by SMZFA was improved in the presence of NaCl. The retention of HA by SMZFA was primarily attributed to HDTMA loaded onto the zeolite surface. However, because modification of ZFA by HDTMA resulted in an increase in Zeta potential, iron oxide in SMZFA also contributed to HA adsorption via a ligand exchange mechanism.

Combined effects of pH (i.e., 7.5, 8.5, and 9.5) and bicarbonate (i.e., 0, 80 and 160mM NaHCO3) on lipid accumulation and on biological contaminant viability in a protozoa-contaminated culture of the freshwater microalga Neochloris oleoabundans were studied. Cultures grown in the media containing 160mM NaHCO3 at pH 9.5 obtained the highest biomass concentration (DCWmax=1.32g/L), lipid content (LC=327mg/g), which corresponded to a lipid productivity of 56mg/(L·d), and the culture was protozoa free one day after inoculation. Other cultures, 160mM NaHCO3 at pH 8.5 (DCWmax=1.32g/L, LC=223mg/g), and 80mM NaHCO3 at pH 9.5 (DCWmax=1.25g/L, LC=264mg/g) could delay protozoan growth, but not inhibit it completely. These results suggest 160mM NaHCO3 or slightly above at pH levels of 8.5-9.5 may be used in outdoor cultivation processes of freshwater N. oleoabundans to control protozoa contamination while maintain a high lipid content.