Removal of Pharmaceuticals and Personal Care Products during Water Recycling: Microbial Community Structure and Effects of Substrate Concentration

Many pharmaceuticals and personal care products (PPCPs) have been shown to be biotransformed in water treatment systems. However, little research exists on the effect of initial PPCP concentration on PPCP biotransformation or on the microbial communities treating impacted water. In this study, biological PPCP removal at various concentrations was assessed using laboratory columns inoculated with wastewater treatment plant effluent. Pyrosequencing was used to examine microbial communities in the columns and in soil from a soil aquifer treatment (SAT; a method of water treatment prior to reuse) site. Laboratory columns were supplied with different concentrations (0.25, 10, 100, or 1,000 μg liter⁻¹) of each of 15 PPCPs. Five PPCPs (4-isopropyl-3-methylphenol [biosol], p-chloro-m-xylenol, gemfibrozil, ketoprofen, and phenytoin) were not removed at any tested concentrations. Two PPCPs (naproxen and triclosan) exhibited removals independent of PPCP concentration. PPCP removal efficiencies were dependent on initial concentrations for biphenylol, p-chloro-m-cresol, chlorophene, diclofenac, 5-fluorouracil, ibuprofen, and valproic acid, showing that PPCP concentration can affect biotransformation. Biofilms from sand samples collected from the 0.25- and 10-μg liter⁻¹ PPCP columns were pyrosequenced along with SAT soil samples collected on three consecutive days of a wetting and drying cycle to enable comparison of these two communities exposed to PPCPs. SAT communities were similar to column communities in taxonomy and phylotype composition, and both were found to contain close relatives of known PPCP degraders. The efficiency of biological removal of PPCPs was found to be dependent on the concentration at which the contamination occurs for some, but not all, PPCPs.     

Biodegradation and removal of pharmaceuticals and personal care products in treatment systems: a review

Pharmaceuticals and personal care products (PPCPs) have been the focus of much recent research as concerns rise about their occurrence in bodies of water worldwide. In an effort to characterize the risk and determine the prevalence of these micropollutants in lakes and rivers, many researchers are examining PPCP removal from impaired water during wastewater treatment and water recycling (soil passage) processes. Biodegradation studies and projects considering combinations of biodegradation and other removal processes have been conducted over a wide range of compound categories and therapeutic classes, as well as across different systems and scales of study. This review summarizes the extent of PPCP removal observed in these various systems.     

How are pharmaceutical and personal care products (PPCPs) removed from urban wastewaters?

The presence of bioactive trace pollutants such as pharmaceuticals and ingredients of personal care products (PPCPs) in different environmental compartments (rivers, lakes, groundwaters, sediments, etc.) is an emerging issue due to the lack of existing information about the potential impact associated with their occurrence, fate and ecotoxicological effects. Due to the low PPCP concentrations reported in wastewaters (ppb or ppt) and their complex chemical structure, common technologies used in sewage and drinking water treatment plants may not be efficient enough to accomplish their complete removal. Information about physico-chemical characteristics such as acidity, lipophilicity, volatility and sorption potential is a useful tool to understand the different removal patterns observed. In order to perform an accurate overall mass balance along the different units of sewage treatment plants, it is necessary to gather information not only about the presence of micropollutants in the aqueous phase, but also on the fraction sorbed onto solids. Since only some PPCPs are very well eliminated by conventional sewage treatment configurations, new strategies such as modification of operating conditions (e.g. solids retention time), implementation of new technologies (e.g. biomembrane reactors) or additional advanced post-treatment steps (e.g. oxidation, adsorption, membranes) have been suggested for an increased efficiency.     

微藻-细菌共生体系在废水处理中的应用

在微藻-细菌协同共生的过程中,藻类光合作用释放的氧气被异养微生物利用来矿化水体中的污染物,细菌呼吸为藻类提供二氧化碳作为碳源。近年来,藻类-细菌协同共生体系在污水处理中的应用得到了广泛的研究。本文重点综述了菌藻协同共生体系中微藻与细菌之间的三种相互作用,以及菌藻协同共生体系在废水处理中的应用。菌藻协同共生体系中的微藻与细菌通过营养交换、信号转导及基因转移等相互作用实现共赢。该体系广泛用于处理富营养化、重金属、药物、多环芳烃(polycyclicaromatic hydrocarbons,PAHs)、石油烃化合物等难降解的有机污染的水体。对于氮、磷等营养物质的去除,其主要机理涉及同化作用、厌氧氨氧化作用、硝化与反硝化作用、磷酸化作用等。对重金属、药物、石油烃化合物及其他有机化合物的去除机制主要是生物吸附、生物富集及细胞内外的生物降解。     

Cultivation and characterization of bacterial isolates capable of degrading pharmaceutical and personal care products for improved removal in activated sludge wastewater treatment

Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment plant (WWTP) effluents are an emerging surface water quality concern. Biological transformation has been identified as an important removal mechanism during wastewater treatment. The aim of this research was the identification of bacteria with characteristics for potential bioaugmentation to enhance PPCP removal. We report here the cultivation and characterization of bacteria capable of degrading PPCPs to ng/L concentrations. An isolation approach was developed using serial enrichment in mineral medium containing 1 mg/L of an individual PPCP as the sole organic carbon source available to heterotrophs until the original activated sludge inocula was diluted to ~10^?8 of its initial concentration, followed by colony growth on solid R2A agar. Eleven bacteria were isolated, eight that could remove triclosan, bisphenol A, ibuprofen, or 17β-estradiol to below 10 ng/L, one that could remove gemfibrozil to below 60 ng/L, and two that could remove triclosan or E2, but not to ng/L concentrations. Most bacterial isolates degraded contaminants during early growth when grown utilizing rich carbon sources and were only able to degrade the PPCPs on which they were isolated. Seven of the bacterial isolates were sphingomonads, including all the triclosan and bisphenol A degraders and the ibuprofen degrader. The study results indicate that the isolated bacteria may have a positive influence on removal in WWTPs if present at sufficient concentrations and may be useful for bioaugmentation.     

Ammonium removal using algae–bacteria consortia: the effect of ammonium concentration,algae biomass,and light

In this study, the effects of ammonium nitrogen concentration, algae biomass concentration, and light conditions (wavelength and intensity) on the ammonium removal efficiency of algae-bacteria consortia from wastewater were investigated. The results indicated that ammonium concentration and light intensity had a significant impact on nitrification. It was found that the highest ammonia concentration (430 mg N/L) in the influent resulted in the highest ammonia removal rate of 108 ± 3.6 mg N/L/days, which was two times higher than the influent with low ammonia concentration (40 mg N/L). At the lowest light intensity of 1000 Lux, algae biomass concentration, light wavelength, and light cycle did not show a significant effect on the performance of algal–bacterial consortium. Furthermore, the ammonia removal rate was approximately 83 ± 1.0 mg N/L/days, which was up to 40% faster than at the light intensity of 2500 Lux. It was concluded that the algae-bacteria consortia can effectively remove nitrogen from wastewater and the removal performance can be stabilized and enhanced using the low light intensity of 1000 Lux that is also a cost-effective strategy.     

A comparison of bacterial removal efficiencies in constructed wetlands and algae-based systems

Constructed wetlands and algae-based systems have been compared regarding their efficiencies on faecal bacteria removal. Two types of constructed wetlands, sub-surface (SSF) and free water surface (FWS) flow systems, and two more types of algae-based systems, high rate algae ponds (HRAP) and maturation pond (MP) have been studied for two years. All systems treated the same wastewater from a rural locality in León (northwest of Spain). Hydraulic retention time was 3 days for both wetland systems, 20 days for the maturation pond and 10 days for the high rate algae pond. Total coliforms, faecal coliforms, faecal Streptococci, Clostridium perfringens, and Staphylococci were analyzed in the influent and effluents of each system. A comparison among the wetland systems showed that SSF were more efficient than FWS system when considering surface removal rates (cfu removed/m²/d). Nevertheless, differences were not statistically significant. Considering mean removal efficiencies (in log unit), results showed that higher reductions were observed in FWS for most of the groups except for clostridia and Staphylococci. Concerning algae-based systems, MP showed higher removal efficiencies than HRAP, getting higher surface removal rates in the HRAP. Generally constructed wetlands were more efficient than algae-based systems when considering both, efficiencies in % and surface removal rates.     

水环境中药物和个人护理品(PPCPs)的污染现状及对藻类的毒性研究进展

药物和个人护理品(PPCPs)因持续排放到水环境且对水生态环境和人类健康造成潜在威胁而受到广泛关注.藻类作为水体重要的初级生产者,对水体的生态平衡和稳定起着重要的作用.本文围绕地表水PPCPs污染,介绍了不同国家和地区地表水体中PPCPs的浓度分布和污染特征,并从毒性效应、生物累积及潜在的生态风险等方面,综述了PPCPs对藻类的污染生态学研究进展,阐述PPCPs对藻类的毒性效应及机制,PPCPs在藻类中的生物累积,以及地表水体PPCPs的生态风险,为地表水体PPCPs的相关标准制定和修订,以及水体生态环境健康风险评价提供参考.     

藻类生物柴油研究现状与展望

随着世界能源危机和环境恶化的加剧,新型绿色燃料——生物柴油备受关注。目前,世界范围内主要以油料作物和动物脂肪为原料生产生物柴油,但存在很多局限性。藻类本身具有很多优点,以藻类为原料生产的生物柴油是真正的环保可再生能源,但是藻类生物柴油的生产工艺费用较高,生产技术还不成熟,仍需要进一步的研究。该文主要介绍藻类生物柴油的优越性、生产工艺以及研究现状,分析了生产过程中存在的问题,展望了未来藻类生物柴油生产工艺研究的重点和发展趋势。     

藻菌共生处理污水的机制与应用研究进展

在污水处理领域,藻菌共生有同步脱氮、除磷效率高、排放温室气体量低、生物质可资源化回收等优势,近年来受到学者的重视.目前鲜有综述污水处理中藻类与细菌、真菌及混合藻菌间互作机制的文章.本文从藻类-细菌、藻类-真菌、混合藻-混合菌3个方面介绍藻菌共生处理污水的研究进展,重点阐述藻菌间营养物质交换、信号传导及生物絮凝3种不同互...     

Rotating algal biofilm reactor and spool harvester for wastewater treatment with biofuels by-products

Maximizing algae production in a wastewater treatment process can aid in the reduction of soluble nitrogen and phosphorus concentrations in the wastewater. If harvested, the algae-based biomass offers the added benefit as feedstock for the production of biofuels and bioproducts. However, difficulties in harvesting, concentrating, and dewatering the algae-based biomass have limited the development of an economically feasible treatment and production process. When algae-based biomass is grown as a surface attached biofilm as opposed to a suspended culture, the biomass is naturally concentrated and more easily harvested. This can lead to less expensive removal of the biomass from wastewater, and less expensive downstream processing in the production of biofuels and bioproducts. In this study, a novel rotating algal biofilm reactor (RABR) was designed, built, and tested at bench (8 L), medium (535 L), and pilot (8,000 L) scales. The RABR was designed to operate in the photoautotrophic conditions of open tertiary wastewater treatment, producing mixed culture biofilms made up of algae and bacteria. Growth substrata were evaluated for attachment and biofilm formation, and an effective substratum was discovered. The RABR achieved effective nutrient reduction, with average removal rates of 2.1 and 14.1 g m(-2) day(-1) for total dissolved phosphorus and total dissolved nitrogen, respectively. Biomass production ranged from 5.5 g m(-2) day(-1) at bench scale to as high as 31 g m(-2) day(-1) at pilot scale. An efficient spool harvesting technique was also developed at bench and medium scales to obtain a concentrated product (12-16% solids) suitable for further processing in the production of biofuels and bioproducts.     

Evaluation of “Classic” and Emerging Contaminants Resulting from the Application of Biosolids to Agricultural Lands: A Review

The presence of detectable amounts of contaminants in treated sewage sludge (concentrations μg/kg – mg/kg) has led to concerns that land applications of biosolids may result in an accumulation of contaminants in the soil and their subsequent translocation through the food chain. Despite advances in wastewater management (e.g., anaerobic, thermophilic, and mesophilic digestion), many compounds and their metabolites remain intact following treatment. This review looks at the main risk factors relating to the occurrence of “classic” (persistent organic pollutants [POPs]) and emerging pollutants (pharmaceuticals and personal care products) in biosolids. Relevant EU legislation and risk assessment strategies for the control of emerging contaminants are also considered. Organic pollutants regulated under the Stockholm Convention on POPs along with PPCPs were identified as contaminants of concern based on the risk factors: persistence, bioaccumulation, and toxicity (PBT). PPCPs were recognized as being of particular concern as their high transformation/removal rates are compensated by their continuous introduction into the environment. This study highlights the growing concern in relation to emerging contaminants in biosolids and highlights risk assessment strategies that can be used to characterize potential human/environmental risks.     

Consortia of cyanobacteria/microalgae and bacteria: biotechnological potential

Microbial metabolites are of huge biotechnological potential and their production can be coupled with detoxification of environmental pollutants and wastewater treatment mediated by the versatile microorganisms. The consortia of cyanobacteria/microalgae and bacteria can be efficient in detoxification of organic and inorganic pollutants, and removal of nutrients from wastewaters, compared to the individual microorganisms. Cyanobacterial/algal photosynthesis provides oxygen, a key electron acceptor to the pollutant-degrading heterotrophic bacteria. In turn, bacteria support photoautotrophic growth of the partners by providing carbon dioxide and other stimulatory means. Competition for resources and cooperation for pollutant abatement between these two guilds of microorganisms will determine the success of consortium engineering while harnessing the biotechnological potential of the partners. Relative to the introduction of gene(s) in a single organism wherein the genes depend on the regulatory- and metabolic network for proper expression, microbial consortium engineering is easier and achievable. The currently available biotechnological tools such as metabolic profiling and functional genomics can aid in the consortium engineering. The present review examines the current status of research on the consortia, and emphasizes the construction of consortia with desired partners to serve a dual mission of pollutant removal and commercial production of microbial metabolites.     

人工湿地与环境卫生安全

人工湿地是国内外应用较为广泛的一种污水处理技术。近年来,人工湿地的环境卫生安全问题越来越受到人们的关注。人工湿地中病原微生物的去除或失活受到诸多因素的影响,其过程和机制与传统的二级污水处理工艺有较大区别,选择适宜的指示微生物和病原微生物并研究其行为是进行人工湿地环境卫生安全评价的关键。本文论述了病原微生物在人工湿地中的归宿以及人工湿地可能对环境卫生安全造成的影响,综述了国内外的研究现状,指出了该方面研究的必要性和迫切性。     

PPCPs removal by aerobic granular sludge membrane bioreactor

An aerobic granular sludge membrane bioreactor (GMBR) was applied to the treatment of pharmaceutical and personal care products (PPCPs) wastewater. The influence of granular sludge on five antibiotic and antiphlogistic PPCPs wastewater and the removal effect of methyl alcohol and conventional organic matter were investigated while constantly reducing the density of inflow organic matter. The results showed that the sludge granulation process in the system was rapid but unstable, and that the system exhibits a dissolution–reunion dynamic equilibrium. The reactor demonstrated varying removal effects of PPCPs on different objects. The use of a GMBR was more effective for the removal of prednisolone, naproxen, and ibuprofen; the first two drugs were lower the average removal rate of which reached 98.46 and 84.02 %, respectively; whereas the average removal rate of ibuprofen was 63.32 %. By contrast, the GMBR has an insignificant degradation effect on antibiotics such as amoxicillin, indicating that such antibiotic medicine is not easily degraded by microorganisms, which plays different roles in system operation. Because of the different chemical structures and characteristics of drugs that result in various degradation behavior. During the GMBR granulation process, the value of mixed liquor volatility suspended solids (MLVSS) gradually increases from 1.5 to 4.1 g/L during the GMBR granulation process, and the removal rate of COD_Cr reaches up to 87.98 %. After reducing the density of organic matter is reduced, the removal rates of NH₃-N and TP both reach more than 90 %, respectively. Moreover, the proposed technique is considerably effective in the removal of methanol.     

Pre-treatment of hospital wastewater by coagulation–flocculation and flotation

Coagulation–flocculation and flotation processes were evaluated for the pre-treatment of hospital wastewater, including the removal of 13 pharmaceutical and personal care products (PPCPs). Coagulation–flocculation assays were performed in a Jar-Test device and in a continuous pilot-scale plant. Raw hospital wastewater as well as the effluent from the continuous coagulation plant were treated in a flotation cell. Removal of total suspended solids (TSS) during pre-treatment was very effective, reaching an average removal efficiency of 92% in the combined coagulation–flotation process. Musk fragrances were eliminated to a high degree during batch coagulation–flocculation (tonalide: 83.4 ± 14.3%; galaxolide: 79.2 ± 9.9%; celestolide: 77.7 ± 16.8%), presumably due to their strong lipophilic character which promotes the interaction of these compounds with the lipid fraction of solids. For diclofenac (DCF), naproxen (NPX) and ibuprofen (IBP) maximum removals of 46%, 42% and 23%, respectively, were obtained, while the rest of PPCPs were not affected by the physico-chemical treatment. Flotation of raw wastewater led to slightly worse results compared to coagulation–flocculation, although the combined action of both improved the overall efficiency of the process. The proposed pre-treatment strategy for hospital wastewater is useful for assimilating its conventional physico-chemical characteristics to that of municipal wastewater as well as for reducing the load of some PPCPs into the sewer system.     

Microalgae wastewater treatment: Biological and technological approaches

Current global environmental issues raise unavoidable challenges for our use of natural resources. Supplying the human population with clean water is becoming a global problem. Numerous organic and inorganic impurities in municipal, industrial, and agricultural waters, ranging from microplastics to high nutrient loads and heavy metals, endanger our nutrition and health. The development of efficient wastewater treatment technologies and circular economic approaches is thus becoming increasingly important. The biomass production of microalgae using industrial wastewater offers the possibility of recycling industrial residues to create new sources of raw materials for energy and material use. This review discusses algae‐based wastewater treatment technologies with a special focus on industrial wastewater sources, the potential of non‐conventional extremophilic (thermophilic, acidophilic, and psychrophilic) microalgae, and industrial algae‐wastewater treatment concepts that have already been put into practice.     

Significance of exploiting non-living biomaterials for the biosorption of wastewater pollutants

Industrial effluents from various sectors have become a matter of major environmental concern. The treatment of wastewater in recent year plays a significant role in order to remove the pollutants and to safeguard the water resource. The conventional wastewater treatment is considered costlier and associated with problem of sludge generation. Biosorption methods are considered as the potential solution due to their economical efficiency, good adsorption capacity and eco-friendliness. In this review, an extensive list of biosorbents from algae, bacteria, fungi and agricultural byproducts have been compiled. The suitability of biosorbents towards the eradication of heavy metals, textile dyes and phenolic compounds were highlighted. It is evident from the literature survey of recently published research articles that the biosorbents have demonstrated outstanding removal potential towards the wastewater pollutants. Therefore, biosorbents from the source of dead microbial and agricultural byproduct can be viable alternatives to activated carbon for the wastewater treatment.     

Engineering microbial consortia: a new frontier in synthetic biology

Microbial consortia are ubiquitous in nature and are implicated in processes of great importance to humans, from environmental remediation and wastewater treatment to assistance in food digestion. Synthetic biologists are honing their ability to program the behavior of individual microbial populations, forcing the microbes to focus on specific applications, such as the production of drugs and fuels. Given that microbial consortia can perform even more complicated tasks and endure more changeable environments than monocultures can, they represent an important new frontier for synthetic biology. Here, we review recent efforts to engineer synthetic microbial consortia, and we suggest future applications.