Potential pathways for antibiotics to enter the environment include release from manufacturing facilities, disposal of unused antibiotics by patients, hospitals, or distributors either to wastewater or to solid waste, patient excretion of and their metabolites to wastewater, use in aquaculture and animal farming.
In the last few years, concerns about the environmental fate and behavior of synthetic organic chemicals for hygienic use, detected in waters have increased. Several of these compounds are used intensively, in large volumes, are persistent, bioactive and exhibit bioaccumulation and endocrine disrupting activity. Some pharmaceuticals, including analgesics, antibiotics, antiepilieptics, beta-blockers, blood-lipid regulators and contraceptives also have the potential to determine various physiologic responses in aquatic organisms. Other compounds (natural hormones and several industrial and household chemicals) able to affect organisms in receiving waters are also endocrine disrupting agents. A lack of information still exists regarding the potential impact associated with the occurrence, fate and ecotoxicological effects of endocrine disruptors, including pharmaceuticals and personal care compounds in the environment since few compounds were inventoried or regulated worldwide. In some cases, there are no legal requirements to assess the impact of long-term exposure to low concentration of these chemicals. This may be because important classes of these compounds have not been studied in detail tip to now due to the non-availability of suitable instrumental techniques, or analytical standards for low concentration levels. Recently, the appearance of sophisticated tests for monitoring environmental contamination has revealed the presence of these types of contaminants at lower levels, down to nanograms per liter. This Constitutes an important tool in the development of guidelines to monitor and/or update environmental compliance reports. The cut-rent survey aims to combine information from the literature on the environmental Occurrence, fate and effects of personal care products and endocrine disrupting agents on the environment; as well as on the treatment options for their removal from wastewaters.
Biochars have high affinity for phosphorus (P) and transform P from readily available P pool to less available P pools. The incorporation of biochars to acidic soil increased the availability of P, whereas in calcareous soil, the application of biochars decreased the availability of P. Application of biochar can also be an effective remedial tool to control P transport from vulnerable catchments.
A significant number of biosorption studies on the removal of heavy metal from aqueous solutions have been conducted worldwide. Nearly all of them have been directed towards optimizing biosorption parameters to obtain the highest removal efficiency while the rest of them are concerned with the biosorption mechanism. Combinations of FTIR, SEM-EDX, TEM as well as classical methods such as titrations are extremely useful in determining the main processes on the surfaces of biosorbents. Diverse functional groups represented by carboxyl, hydroxyl, sulfate and amino groups play significant roles in the biosorption process. Solution pH normally has a large impact on biosorption performance. In brief, ion exchange and complexation can be pointed out as the most prevalent mechanisms for the biosorption of most heavy metals.
The dramatic growth in ionic liquid research over the past decade has resulted in the development of a huge number of novel ionic liquids, as well as many associated applications. The perceived environmentally friendly nature of ionic liquids, which results from their negligible vapor pressure, is now under scrutiny since although they will not evaporate into air, it is not possible to guarantee that they will never enter the environment. Toxicity research studies including ecotoxicity, have recently received broad attention and the commonly accepted notion that ionic liquids have low toxicity has been shown to be incorrect. This review attempts to highlight the progress of ionic liquid toxicity research, as well as the development of degradable and bio-renewable ionic liquids.
The magnetization of adsorbents and the use of magnetic separation techniques can be an effective way to resolve the problems associated with separation and filtration. Activated carbon modified by magnetite nanoparticles (Fe 3 O 4 @C) showed a high potential and dsorption capacity for the removal of Pb 2+ ions from aqueous solution. It can be potentially applied for avoiding secondary pollution and be used in full‐scale and industrial applications.
Nickel is an essential nutrient for plants. However, the amount of Ni required for normal growth of plants is very low. Hence, with the level of Ni pollution in the environment increasing, it is essential to understand the functional roles and toxic effects of Ni in plants. We briefly review advances in relevant research over the past 20 years. Based on the available data, two new indirect pathways of Ni toxicity in plants are proposed. These are (i) interference with other essential metal ions and (ii) induction of oxidative stress. Research should focus on these mechanisms at the protein and molecular levels, Further research should also be directed at plant species that are capable of accumulating Ni at high concentration, so-called hyperaccumulators. Such species can provide model systems to study the mechanisms of Ni tolerance and can also be used for phytoremediation by removing nickel from polluted environment.
Textile industry is one of the fastest growing industries and significantly contributes to the economic growth in Malaysia. However, this industry also has high water consumption and subsequently produces high discharge rate of wastewater with high load of contaminants. The release of dyes into the environment during textile fiber dyeing and finishing processes is a main source of water pollution. Individual wastewater treatment through physical, biological, or chemical method is often very costly and results in large amount of sludge. Thus, there is a need to look for alternative treatment processes that covers from pre to post wastewater treatment stage. This paper reviews the current scenario with respect to textile industry effluent in Malaysia and technologies available for the treatment of the effluent. Prospects, challenges, and recommendations for future direction as well as on‐going research works dedicated to the treatment of textile wastewater are also reviewed in detail. In Malaysia, biological treatment methods gain popularity in the textile industries, due to the economical factor. An implementation of recycled wastewater to be reused for dyeing and finishing processes could save at least 50% of the overall water demand.
Lemnaceae or duckweed is an aquatic plant that can be used to recover nutrients from wastewaters. The grown duckweed can be a good resource of proteins and starch, and utilized for the production of value-added products such as animal feed and fuel ethanol. In the last eleven years we have been working on growing duckweed on anaerobically treated swine wastewater and utilizing the duckweed for fuel ethanol production. Duckweed strains that grew well on the swine wastewater were screened in laboratory and greenhouse experiments. The selected duckweed strains were then tested for nutrient recovery under laboratory and field conditions. The rates of nitrogen and phosphorus uptake by the duckweed growing in the laboratory and field systems were determined in the study. The mechanisms of nutrient uptake by the duckweed and the growth of duckweed in a nutrient-limited environment have been studied. When there are nutrients (N and P) available in the wastewater, duckweed takes the nutrients from the wastewater to support its growth and to store the nutrients in its tissue. When the N and P are completely removed from the wastewater, duckweed can use its internally stored nutrients to keep its growth for a significant period of time. A modified Monod model has been developed to describe nitrogen transport in a duckweed-covered pond for nutrient recovery from anaerobically treated swine wastewater. Nutrient reserve in the duckweed biomass has been found the key to the kinetics of duckweed growth. Utilization of duckweed for value-added products has a good potential. Using duckweed to feed animals, poultry, and fish has been extensively studied with promising results. Duckweed is also an alternative starch source for fuel ethanol production. Spirodela polyrrhiza grown on anaerobically treated swine wastewater was found to have a starch content of 45.8% (dry weight). Enzymatic hydrolysis of the duckweed biomass with amylases yielded a hydrolysate with a reducing sugar content corresponding to 50.9% of the original dry duckweed biomass. Fermentation of the hydrolysate using yeast gave an ethanol yield of 25.8% of the original dry duckweed biomass. These results indicate that the duckweed biomass can produce significant quantities of starch that can be readily converted into ethanol.
The literature review showed that there is a lack of consensus between design guidelines as to whether or not a geofabric should be included between the aggregate layers of pervious pavements. The study concluded that the inclusion of a geofabric layer in the pavement structure may significantly decrease the infiltration rate of the pervious pavement system and could potentially reduce the structural integrity of the pervious pavement.
An overview on reported information on low cost granulated adsorbents for safe drinking water production is presented. Important features of granular adsorbents and granulation processes: pilot and field‐scales implemented arsenic removal technologies and self‐reliance clean water provision at household level has been anticipated to minimize drinking water related health consequences.
Advances in science and technology have resulted in the rapid development of modern society, which is clearly unsustainable because of the strain it places on current resources. The energy and materials needed to sustain the present society are derived primarily from non-renewable fossil resources, which will be depleted at some point. Plastics are one example of an important commodity in the modern lifestyle. While plastics are undoubtedly superior materials in terms of their costs, processability and functional properties, they are currently derived from fossil resources and they are not readily assimilated by the various ecosystems upon disposal. The search for biodegradable plastics that are derived from renewable resources has been ongoing since the 1970s. Two of the most promising biobased plastics, i.e., polylactic acid and polyhydroxyalkanoates, have received much attention as potential alternatives to existing processes. This article will discuss the current status and sustainability of these two next generation biobased plastics by taking into consideration the raw materials required, as well as the post-consumption effects of these materials on the environment. In addition, important issues surrounding the development and sustainability ofbiobased and biodegradable plastics will be highlighted.
Biochar, a by-product of biomass pyrolysis, has been suggested as a mean to combat climate change, and at the same time to achieve agricultural and environmental benefits. As one possible source of the components with high aromatic structure in soil humus, biochar is of great importance in increasing soil carbon storage and improving soil nutrient retention and nutrient availability, and in maintaining the balance of soil ecosystem. This paper briefly reviewed and synthesized recent findings and discussions regarding the production and characteristics of biochar, its effects on global climate change and particularly in relation to the environmental effects of biochar in soils. Agronomic benefits of biochar application are critically highlighted because researches show that biochar had varied effects on crop productivity thorough the different bio-physical interactions between the biochar and the soils, which are deserved for further investigations. Potential pitfalls and knowledge gaps were briefly discussed on the environmental behavior and the effects of biochar in agricultural ecosystem.
Converting renewable carbon to chemicals and fuels is experiencing a huge increase in both research and commercial interest. The biorefinery is now a recognized approach for transforming renewable raw materials into separate biobased process streams, and ultimately, marketplace chemicals and fuels. Successful biorefinery operation will fulfill two strategic goals: displacing nonrenewable raw materials (all energy goal, met by production of biofuels) and providing economic incentive to support a robust biorefining industry (an economic goal, met by the production of high value chemicals). These goals are met simultaneously by integrating chemical and file] production within a single operation. However, a primary barrier to biorefinery development is the relative lack of technology available for the conversion of renewable carbon sources into useful marketplace chemicals and materials. Developing broad based technologies capable of producing families of high value chemicals will provide a significant opportunity for the biorefinery. This introductory paper briefly overviews the biorefinery concept and describes several features of biorefinery operation and technology needs for the production of chemicals from renewable raw materials.
Over the past 30 years the literature has burgeoned with in situ approaches for groundwater remediation. Of the methods currently available, the use of metallic iron (Fe0) in permeable reactive barrier (PRB) systems is one of the most commonly applied. Despite such interest, an increasing amount of experimental and field observations have reported inconsistent Fe0 barrier operation compared to contemporary theory. In the current work, a critical review of the physical chemistry of aqueous Fe0 corrosion in porous media is presented. Subsequent implications for the design of Fe0 filtration systems are modeled. The results suggest that: (i) for the pH range of natural waters (>4.5), the high volumetric expansion of Fe0 during oxidation and precipitation dictates that Fe0 should be mixed with a non-expansive material; (ii) naturally occurring solute precipitates have a negligible impact on permeability loss compared to Fe0 expansive corrosion; and (iii) the proliferation of H2 metabolizing bacteria may contribute to alleviate permeability loss. As a consequence, it is suggested that more emphasis must be placed on future work with regard to considering the Fe0 PRB system as a physical (size-exclusion) water filter device.
The Water Framework Directive (WFD) was established for the protection of surface waters (rivers, lakes, transitional and coastal waters) and ground waters in the European Union. The main environmental objective is to achieve and maintain a good status for all waters by the target date of 2015. Models which are able to address the majority of environmental objectives are proposed within the WFD to inform the management changes required to meet current water policy goals. The use of the Soil and Water Assessment Tool (SWAT) catchment model is widespread throughout the world, especially to support river basin management as required by the WFD. This paper provides a critical evaluation of the use of the model by placing model performance in the Axe catchment, UK, in the context of international performance of the model. Within the constraints of the available data, SWAT represents hydrology, sediment and ortho-phosphorus concentration well for this heterogeneous catchment, but the representation of daily nitrogen concentration dynamics is poor. Temporal aggregation of model outputs from daily to monthly improved the performance metrics for all the river outputs, including nitrate. Wider review of SWAT studies showed widespread reporting of monthly performance metrics within the SWAT studies, despite the model operating at a daily time step. Poor performance for nitrate identified in this current study may be a significant factor in the choice to not report daily results. This demonstrates the importance of ascertaining the reasons for the use of temporal aggregation in modelling studies.
Sample pretreatment methods, such as separation and/or preconcentration prior to the determination of metal ions have developed rapidly due to the increasing need for accurate and precise measurements at extremely low levels of ions in diverse matrices. This review covers new sorbents including microorganisms and nanomaterials used for the solid-phase extraction of metal ions from various sample matrices. A literature survey of the last three years (2005-2007) offering a critical review of these new sorbents available for use in trace metal enrichment is provided. To keep the focus on new sorbents, some of the papers relating to well-known sorbents such as activated carbon are excluded.
Water treatment with metallic iron (Fe-0) is still based on the premise that Fe-0 is a reducing agent. An alternative concept stipulates that contaminants are removed by adsorption, co-precipitation, and size-exclusion in a reactive filtration process. This article underlines the universal validity of the alternative concept. It is shown that admixing non-expansive material to Fe-0 as a pre-requisite for sustainable Fe-0-based filtration systems. Fe-0-based filters are demonstrated an affordable, appropriate, and efficient decentralized water treatment technology.
Adsorptive removal of toxic amaranth dye by alumina reinforced polystyrene (ARP) composite was studied as a function of contact time, pH, initial dye concentration, and temperature. The results indicated that adsorption was strongly dependent on pH and temperature of the dye solution. The adsorption was favored at low pH with the maximum removal at pH 2.0. Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) models were used for the description of adsorption equilibrium data and the best interpretation for the experimental data was given by the D-R model. The adsorption kinetics was tested using pseudo first order, pseudo second order, Elovich, intraparticle, and film diffusion models and the removal by ARP followed a pseudo second order kinetics. Thermodynamic studies revealed that both adsorption and desorption was spontaneous and endothermic in nature. From the exhausted adsorbent, about 70 and 96% desorption was obtained with (99%) CH3OH and 0.1M NaOH, respectively.
Floating treatment wetlands can be exploited to treat various kinds of polluted water. In this system, plants are vegetated on a floating mat and their roots are extended down to the contaminated water acting as biological filters. The plants take up nutrients and trace metals whereas microorganisms degrade organic matter.