Abstract

This research is about how farmers adapt to water scarcity. Using experimental economics methods, field experiments were carried out in a region exposed to severe water scarcity in Colombia. Willingness of water users to cooperate in conforming to extraction caps, as a means of adapting to water availability declination was calculated. Two information treatment groups were implemented in order to assess water allocation decisions when: (i) the amount of water was reduced and (ii) time before aquifer exhaustion was announced. Extant literature on cooperation in common-pool resources (CPR) has focused on demonstrating to what extent resource users depart from egoistic attitudes. Alternatively, the sustainability of water resources requires more research to further understand cooperative behavior. Since the literature on water scarcity is classified in three orders, namely physical, institutional, and socio-political, behavioral dimensions are suggested as a subdivision of the social order. This, in turn, may help to operationalize strategies aimed at improving adaptation to all orders of scarcity. The quantitative results suggest that farmers are inclined to follow the cap. The main difference between the quantity and time treatments differs in that in the time treatments farmers allocate much more water to be consumed in the future, whereas in the former, they prefer to allocate more water to be consumed in the present. Adaptation options provide favorable inputs for implementing the Sustainable Development Goals, especially SDG 6, which is related to water use efficiency. Target 6.4 establishes that, by 2030, water efficiency and extraction sustainability should be accomplished. Thus, water policy interventions might benefit from this contribution. However, since success in water conservation programs might be difficult to achieve due to complexity in human-decision making, more research is needed to deepen our understanding of cooperation drivers in aquifer conservation.

Introduction

Despite the abundance and precision of current information on aquifers status ( van der Gun, 2022 ), this type of data – commonly managed by governmental institutions – rarely flows to the communities that depend upon them ( Margat & van der Gun, 2013 ). In effect, underground water availability data is currently assessed through satellite and underground monitoring of aquifer levels, but farmers´ communities do not have access to this information in a format they can readily use. Climate change is entering the aquifer overexploitation game as a new player ( Damania et al., 2017 ), since droughts are becoming more frequent than in the past ( UNWATER, 2023; Yuan et al., 2023 ); therefore, public environmental and water entities promote water conservation during droughts. Public entities usually stimulate the reduction of water extraction volumes by instructing users to consume less or save the resource. This information, however, lacks the necessary context and specificity, two features that play an important role in water extraction curbing adapted to ensuing water scarcity.

Although water scarcity has an important political dimension ( Metha, 2007 ), from the perspective of its physical and social dimensions, it can be observed how climate change is motivating farmers towards strategies to face the challenge. In spite of the complexity of hydrogeological information, farmers certainly want to know more about the status of the aquifers they are exploiting. They need information not only about the effects of their extraction decisions, but also about the way to moderate these decisions as an adaptation to scarcity according to aquifers’ statuses.

Conclusions

This article was designed for presenting the results on how farmers adapt to water scarcity. Framed field experiments were run to collect quantitative data on the decisions made by farmers when they were exposed to reductions in water availability. Time and water quantity treatment groups were prepared to test their effects on water allocation as limited by suggested extraction caps. Quantitative and qualitative analysis of data and information were carried out. Behavioral regularities and social institutions were drawn from the quantitative data and graphics and the narratives expressed by the players after the experiments.

The setting for the understanding of adaptation strategies was demarcated by the limits imposed by nature. For this reason, water availability as a physical limiting factor for water extraction was used as an instrument to connect allocation, decision-making and intertemporal consequences for adaptation. Thus, limited availability under time and quantity limits pushed the farmers (players) to decide whether to cooperate or not in water conservation. Thus, the individuals who cooperated better were adapting to water scarcity. More precisely, the farmers informed on time before aquifer exhaustion, revealed greater awareness about the possibilities of cooperation. Contrarily, in the control group situation, farmers allocated much more water to all uses and the cap volume was reached in most of the rounds. While in the time and quantity treatment groups, the aggregated water volumes declined through the time (rounds), in the control group this amount averaged 1800 m3 (close to the cap). It can be said that the communication amongst farmers on how to manage remaining stocks, and, similarly the hydrogeological information play a key role in incentivizing the cooperative behavior under extraction caps contexts. Since the stability of cooperation was part of the research aims, providing quantitative information to farmers on extraction decisions and the remaining time of aquifer availability is suggested as a key factor to more effectively address the adaptation to water scarcity.

Abstract

Significant population growth with rapid economic development have led to water scarcity problems around the world. Currently, most of the simple water scarcity assessment methods only refer to per capita water use, failing to take into account actual water availability and actual human domestic water use. Therefore, we have developed a simple and practical method to assess water scarcity, incorporating total water resources, water use efficiency, and the proportion of domestic water. In this approach, a new water scarcity index is employed to describe different levels of water scarcity using various thresholds based on the basic daily human water use per person. This may help to visualize the extent of water scarcity in a region while focusing on human interests. To illustrate this approach, we take China–the world’s largest developing country–as an example, analysing its nationwide water scarcity in 2021 while validating it with the results of other scholars on China’s water scarcity. The results show that our water scarcity assessment index is very accurate, revealing that in 2021, the disparity in water resources between the northern and southern regions of China remains substantial, with severe water scarcity still widely concentrated in northern China.

Introduction

Continuous water supply plays a vital role in daily life and social development ( Ethaib et al., 2022 ). However, increasing water consumption is due to the significant population growth and rapid economic development, resulting in extremely high water resource pressures, which cause water scarcity in numerous places around the world ( Liu et al., 2017 ). For instance, in regions such as Greater London with high population density, intense irrigation present in areas like the High Plains of the United States, and nations like India that exhibit both traits, there is a prevalent issue of water scarcity ( Mekonnen and Hoekstra, 2016 ). Nevertheless, in addition to direct water supply shortages caused by the forces of nature, human factors, as well as socio-political factors, are often overlooked, leading to the masking of the causes of scarcity. This complexity of water scarcity is labelled by Mehta as ‘real’ scarcity (related to socially and ecologically relevant physical phenomena like grass cover, fodder, distance to water for disadvantaged groups, cycles of natural resource abundance and scarcity, agro-meteorological hydrology, etc.) and ‘manufactured’ scarcity (constructing water scarcity as a perpetual and pervasive natural phenomenon, the industry of disaster relief and drought relief, and perverse benefits) ( Mehta, 2003 ). Moreover, there are also sudden and uncontrolled factors affecting water resources, such as the outbreak of the COVID-19 pandemic crisis, which has put many additional pressures on water resources, including the increase in local agricultural irrigation brought about by the localised production of food, and the parallel alteration of the virtual water trade caused by the changes that have taken place in the food trade ( Al-Saidi and Hussein, 2021 ).

Results

3.1. Statistical analysis of the results

A comparison of the water scarcity index calculated using Eq. (1) for each region of China, with a threshold of 0.2 (no stress), is shown in Fig. 2 . The results show that most regions in China are still suffering from water problems, including some economically developed cities with heavy water problems, such as Beijing (0.01), Tianjin (0.008), and Shanghai (0.02). In contrast, Qinghai (1.43) and Xizang (10.56) have abundant water resources, which are significantly higher than in other regions.

3.2. Spatial analysis of the results

In this study, ArcGIS Pro software was used to raster water resource data from various provinces in China in order to comprehensively and visually assess water scarcity across the country. As can be seen in Fig. 3 , the water scarcity index shows obvious spatial distribution differences, mainly between the northern and southern regions of China. Overall, the water scarcity index shows absolute scarcity in the north and no stress in the south. Specifically, a wide range of areas in northern China, including Inner Mongolia, Liaoning, and Shaanxi, exhibit water scarcity and some pressure on water resources. It is worth noting that some areas in the north also show absolute water scarcity, especially in Beijing, Tianjin, Hebei and Shanxi, indicating that the available water resources in these regions do not meet the minimum basic human needs of the region.

Abstract

Introduction

Wastewater in area of focus

Nanotechnology in water purifcation

Nano‑adsorption

Microbial agent

Nanocomposites

Types of nanocomposites

Synthesis modes for nanocomposites

Graphene oxide‑based composites as a disinfectant

Zinc oxide nanocomposites as disinfectant

Copper oxide nanocomposites

Silver/silver oxide nanocomposites

Titanium oxide nanocomposites

Discussion

Conclusion

References

Abstract

     Water is crucial for the existence of life. The world, however, is facing a global water crisis. There are variety of microorganisms, gases and other toxins responsible for water contamination. Various types of nanomaterials exist that have enormous potential to treat contaminated water (water containing metal toxins or specific organic or inorganic impurities) due to their unique properties such as a high surface area and their ability to work effectively even at low concentrations. In recent years, scientists have been giving considerable attention to the application of nanocomposites for water purification, wastewater treatment, microorganism elimination, chemical contaminants, heavy metals removal and so forth. The incorporation of different nanofillers such as carbon nanotubes, graphene oxide, 2D materials, zinc oxide, titanium dioxide, copper and silver nanoparticles into polymeric materials has facilitated important advances, such as suppressing the accumulation of pollutants and foulants, improving the hydrophilicity, increasing the efficiency and improving the mechanical properties. This review discusses leading advances in the development of nanocomposites for antimicrobial and wastewater treatment with the aim of providing an improved understanding of nanocomposites and their applications in antimicrobial and wastewater treatment.

Introduction

     Water is a basic requirement for human life. However, we are far from meeting global requirements for clean water, and this issue will continue to grow over the time (Hillie and Hlophe 2007; Elwakeel et al. 2020b). The demand of clean drinking water is rising as a result of the deterioration of water quality, global climate change and population growth (Tchobanoglous et al. 1991; Elwakeel et al. 2020d). Emissions of organic dyes and heavy metal ions from the paper, leather and textile industries are a serious problem, as they are potentially mutagenic and carcinogenic. To meet environmental requirements, wastewater contaminated with these organic and inorganic species need to be treated before being discharged (Santhosh et al. 2016; Elwakeel et al. 2021). Heavy metals are widely used in various industries for many purposes, including mining and pigment production. Synthetic dyes are also an important type of pollutant, and their sources for water contamination include the textile, pulp and paper, tinting, printing, painting and tanning industries. The removal of dye from such wastewater is a challenging task, as pigments and synthetic dyes are biodegradation-resistant and remain in the environment for a long time. The destruction and handling of organic dyes is therefore an important issue, and a cost-efective method for removing dye substances from wastewater has been developed (Santhosh et al. 2016; Elwakeel et al. 2018).

Conclusion

     This paper explores the existing nanocomposites used to extract heavy metal ions and dyes from wastewater as efective adsorbents. This article addressed recent developments in nanomaterials as economical and environmentally sustainable water purifcation adsorbents. This review highlights fve commonly used nanomaterials/nanoparticles that are used in most existing nanocomposites. In this review, we concluded that TiO2-based nanocomposites have been used for photodegradation activity by most of the researchers in the literature. Silver-based nanocomposites are mostly used for antimicrobial activity. Silver and GO-based nanocomposites were used for the removal of green dye, anionic dye and Cu(II). Copper-based nanocomposites are mostly used for adsorption and photodegradation activity. Zinc oxide nanocomposites are used for adsorption, antimicrobial and photodegradation activity. Finally, we concluded that GO also greatly contributes to the improvement of other materials’ efciency. Further, much needs to be done to control the two-dimensional GO sheets for advanced technologies in the future. There are many challenges and obstacles associated with handling wastewater, and many precautions are required to prevent environmental and health problems. Therefore, new modern wastewater treatment equipment should be versatile, low-cost and commercially efective.

Abstract

     Cross-drainage hydraulic structures such as culverts and bridges in urban landscapes are prone to get blocked by the transported debris (e.g., urban, vegetated), which often reduces their hydraulic capacity and triggers flash floods. Unavailability of relevant data from blockage-originated flooding events and complex nature of debris accumulation are highlighted factors hindering the research within the blockage management domain. Wollongong City Council (WCC) blockage conduit policy is the leading formal guidelines to incorporate blockage into design guidelines; however, are criticized by the hydraulic engineers for its dependence on the post-flood visual inspections (i.e., visual blockage) instead of peak floods hydraulic investigations (i.e., hydraulic blockage). Apparently, no quantifiable relationship is reported between the visual blockage and hydraulic blockage; therefore, many consider WCC blockage guidelines invalid. This paper exploits the power of Artificial Intelligence (AI), motivated by its recent success, and attempts to relate visual blockage with hydraulic blockage by proposing a deep learning pipeline to predict hydraulic blockage from an image of the culvert. Two experiments are performed where the conventional pipeline and end-to-end learning approaches are implemented and compared in the context of predicting hydraulic blockage from a single image. In experiment one, the conventional deep learning pipeline approach (i.e., feature extraction using CNN and regression using ANN) is adopted. In contrast, in experiment two, end-to-end deep learning models (i.e., E2E_ MobileNet, E2E_ BlockageNet) are trained and compared with the conventional pipeline approach. Dataset (i.e., Hydraulics-Lab Blockage Dataset (HBD), Visual Hydraulics-Lab Dataset (VHD)) used in this research were collected from laboratory experiments performed using scaled physical models of culverts. E2E_ BlockageNet model was reported best in predicting hydraulic blockage with R2 score of 0.91 and indicated that hydraulic blockage could be interrelated with the visual features at the culvert.

Introduction

     Blockage of cross-drainage hydraulic structures such as culverts and bridges is a commonly occurring phenomenon during floods which often results in a reduced hydraulic capacity of the structure, increased damages to property, diversion of flow, downstream scour, failure of the structure, and risk to life [13, 22, 25, 26, 34, 53,54,55]. Few highlighted examples of blockage-originated floods around the world include Newcastle (Australia) floods [25, 61], Barpeta (India) floods [59], Pentre (United Kingdom) floods [15] and Wollongong (Australia) floods [25, 54]. In the context of Australia, many councils and institutions have mentioned blockage as a critical issue (e.g., NSW Floodplain Management Manual [49], Queensland Urban Drainage Manual [35], Australian Rainfall and Runoff (ARR) [10, 26, 50, 62]), however, none comprehensively addressed consideration of blockage into design guidelines. Research in blockage management is hindered by the highly variable nature of blockage formulation and the unavailability of historical floods data to investigate the behavior of blockage [16, 17, 38]. Wollongong City Council (WCC), under the umbrella of ARR, developed a conduit blockage policy for the first time to incorporate the blockage within the design guidelines [36, 62]. The WCC policy suggested that any hydraulic structure with a diagonal length less than 6m is prone to 100% blockage during peak floods.

Conclusion

     Deep learning pipeline and end-to-end deep learning models have been successfully implemented and compared by performing two experiments in the context of predicting the hydraulic blockage from a single image of the culvert. Experiment one implemented a conventional deep learning pipeline using CNN and ANN to extract the visual features and predict the hydraulic blockage, respectively. MobileNet CNN model with two-layer ANN (i.e., ANN1) was reported best with R2 score of 0.69. Regression performance was observed to be degraded with the increase in the number of extracted visual features, which may be attributed to the presence of increased number of irrelevant and uncorrelated features. Experiment two implemented end-to-end deep learning models to achieve the functionality of the conventional deep learning pipeline and compared the results. From the results of experiment two, the end-to-end learning approach was reported to outperform the conventional pipeline by a significant margin (i.e., R2 of 0.91 for E2E_ BlockageNet in comparison to 0.69 for the conventional pipeline). Improved performance of end-to-end models may be attributed to their capability of self-optimizing the internal components of the network. A positive R2 score for all cases validated the hypothesis of the existence of a relation between visual features of the culvert and corresponding hydraulic blockage. The performance of proposed models is expected to be degraded significantly for the cases where the image contains a background with a similar visual appearance to the debris material blocking the culvert. The development of data pre-processing techniques to mitigate the visual variations caused by other factors (e.g., lighting, debris type, background, weather) is a potential future research direction. Furthermore, deployment of the proposed approach using the AIoT infrastructure for real-world culvert sites is also planned in the near future.

Abstract

     Access to healthy drinking water is vital to human health and development. Bottled water consumption has been on the rise in recent years. As several chemical and bacteriological parameters affect bottled water quality, it is difficult to choose the highest-quality bottled water. Numerous studies have proposed the use of multiple-criteria decision-making (MCDM) methods to overcome this problem. Herein, the two-stage fuzzy analytic hierarchy process (FAHP) and technique for order preference by similarity to ideal solution (TOPSIS) method were adopted to rank different brands of bottled water. The FAHP approach allows working at the intervals of judgment rather than absolute values. TOPSIS is a technique for ordering performance based on its similarity to the ideal solution. An expert panel selected and classified the criteria and sub-criteria. A pairwise comparison questionnaire was then developed, and the weights of the criteria and sub-criteria were assigned by water quality experts. The data on the quality of different brands of water were collected from the Iranian bottled water database. The final data analysis and weight determination of each parameter were performed in Excel and R software Programs. Finally, the CCi (value of closeness coefficient) and rank of 71 bottled water brands were calculated, and the best brand was introduced. Among the selected criteria, carcinogenic chemical compounds with the weight of 0.368 were the most important compound in ranking bottled water brands, followed by bacteriologic, pathogenic chemical compounds, chemical compounds important in terms of toxicity, nutritious chemical compounds with a low toxicity level, chemical compounds related to esthetic effects, and chemical compounds without health effects, respectively.

Introduction

     A challenge currently faced by developing countries is the lack of access to healthy drinking water (Abuzerr et al. 2019; Cobbina et al. 2015). Based on the World Health Organization’s (WHO) report, about 663 million people worldwide do not have access to healthy drinking water (WHO 2017). The increased population growth, a lack of healthy drinking water, and the public opinion about good taste, health, and appropriate quality have increased bottled water consumption. This rise has been considered in the past three decades, with the highest consumption being reported in developing countries of Asia and South Africa (Hu et al. 2011). The bottled water sale rate was $198.50 billion in 2017, a value which is estimated to reach $307.2 billion by 2024 (Doria 2006). Therefore, access to healthy drinking water is vital to human health and development (Fisher et al. 2015).

     Natural processes (erosion) and anthropogenic activities (electroplating, metal smelting, and chemical industries) are the main sources of pollutant entrance into the water. Although a few heavy metals are essential to human health, their excess amount can have negative efects such as anemia, renal dysfunction, cancer, and brain damage (Chowdhury et al. 2016; Gharibi et al. 2012; Qu et al. 2020; Qu et al. 2021a, b; Rezaee et al. 2015; Zhang et al. 2021). The existence of numerous parameters afecting water quality complicates bottled water quality assessment and ranking and decisionmaking about the purchase of the best and highest-quality brand. Therefore, there is a dire need for precise and logical techniques for accurate and scientifc decision-making. To this end, studies have proposed various methods for choosing the best option and making the decision, among which MCDM methods have received considerable attention owing to their numerous advantages (Kou et al. 2014; Mulliner et al. 2016).

Conclusion

     The quality assessment and selection of the best bottled water brand are difcult due to the efect of various physical (temperature and turbidity), chemical (heavy metals, anions, and cations), and bacteriological (Pseudomonas and coliforms) parameters on water quality and the existence of numerous brands in the market. Herein, by using the MCDM method (FAHP-TOPSIS), the quality of 71 bottled water brands in the Iranian market was ranked. The application of MCDM approaches in various sciences indicates these methods’ strong capability in evaluating problems that possess multiple criteria. These methods accurately assess bottled water quality and aid the customer in selecting a higher-quality brand. They can, therefore, be adopted to create competition among manufacturers to produce higher-quality products. In this study, the grouping and weighting of elements were based on the opinions of Iranian experts and by taking into account the local conditions of Iran. For global applications, a comprehensive model can be proposed for water quality assessment by considering other chemical and bacteriological parameters afecting water quality and with the participation of international experts from other countries.

The aim of this study is to assess the water quality of Lower Jhelum Canal (LJC) and its suitability for irrigation purposes. An effort has been made to develop a method by integrating water quality index with geographic information system (GIS) for an effective interpretation of LJC water quality. The pollution status of LJC was estimated by different physicochemical and biological parameters. Based on results of analysis, a spatial distribution map of selected water quality parameters was prepared using GIS. An inverse distance weighting (IDW), which is an interpolation technique, was applied to prepare a thematic layer of parameters at each station of Lower Jhelum canal. The results of individual parameters showed that the concentrations of contamination were within permissible limits of WHO and NEQS guidelines except for E. coli. Overall, most of the water falls in excellent quality category indicating the suitability of water for irrigation purpose. The results suggest that most of the water can be used for irrigation and various intended purposes except direct use of water for potable or drinking purposes without treatment.

Introduction

Water is the most significant ingredient for supporting and evolution of life (Kuutondokwa, 2008). Humans get different sorts of benefits from freshwater, which includes water for drinking, industrialization, domestic uses, irrigation, for the production of waterfowl and fisheries, use for leisure, shipping, and waste discarding (Jackson et al., 2001). Water is a source of economic gain. Almost 70% of water is used in agricultural production, which is indirectly the cause of economic growth (Brown and Matlock, 2011). Water resources (Freshwater) are becoming limited for individuals due to overpopulation, so the accessibility of freshwater for human beings decreases (Iqbal et al., 2018). Quality of freshwater deteriorates by developmental activities that contaminate the water bodies, their effects on human health, ecosystem disturbance and issues related to its management and monitoring (Iqbal et al., 2019). Water quality deterioration is the primary threat to public health at the global level (Rahman et al., 2020). Anthropogenic actions, like improper disposal of municipal, industrialized effluents, and unsystematic use of chemicals in agriculture, are vital aspects causative in the worsening of water quality (Azizullah et al., 2011; Iqbal et al., 2020; Subedi et al., 2019; Shirani et al., 2018; Li et al., 2020). The result of these activities is eutrophication, loss of water quality, loss of biodiversity, effects on human health and social security, deposition of nutrients and other inorganic pollutants, acidification and significant economic losses (Kraemer et al., 2001). Contamination of water leads to water scarcity or it may be polluted at that level where it is expensive to treat (Gupta et al., 2012; Maged et al., 2020; Imran et al., 2020). Consequences of both water treatment and water scarcity with high cost would be the reason for the increase in water prices (Kuutondokwa, 2008). According to (Rogers et al., 2002), water is an efficient good. However, the nations which have water resources could grow their economies, while on the other hand, it will be difficult for poor or developing countries, even to avail of their essential needs.

Abbreviations

1. Introduction

2. Method and analysis section

3. Petrochemical wastewater pretreatment and advanced treatment

4. Future perspectives

Acknowledgements

Appendix A. Supplementary data

References

Abstract

Petrochemical wastewater is a major industrial source of pollution that produces a variety of refractory and toxic organic pollutants that are detrimental to animals and plants in natural water bodies; it is especially harmful to biological treatment systems. Regardless of these threats, studies on these specific organic pollutants are limited at present. Consequently, it is extremely essential to promote relevant problem solving efficiently. Currently, only limited processes are available for pretreatment of high-concentration wastewater, and advanced treatment of secondary effluent as compared to the conventional treatment are introduced by current studies. Therefore, in this review, we have systematically generalized the characteristics of petrochemical wastewater; we have particularly summarized and compared different methods (recent developments, influencing factors, etc.) which are applied in pretreatment and advancement of current methods. Additionally, the interaction mechanisms of microbes under a wide range of concentrations of specific organic pollutants and associated degradation pathways have been described comprehensively. Moreover, we have analyzed bioenergy recovery from the degradation/removal of specific organic pollutants with environmental-friendly and economically methods because it can help realize the goal of circular resource utilization during the process of detoxification and minimization.

Introduction

The petrochemical industry is a fundamental industry that plays an essential role 4 in any country’s national economy and provides support to many other sectors, such as agriculture, energy, transportation, etc. (Fig. 1) (Clews, 2016c; Jafarinejad 2017).  Petrochemical wastewater is generated via several routes from this industry, including effluent from raw materials, factory rainwater, cooling water, and domestic sewage. It has been reported that global petroleum production has reached 4.40 billion tons based on related industrial statistics (https://www.sohu.com/a/119515720_122917). Moreover, relevant studies have revealed that 3.00-3.50 m3 10 of petrochemical wastewater is generated per ton of petroleum refinery process (Zhang and Fan, 2016; 12 Siddique et al., 2017). For instance, China’s annual industrial wastewater discharge is 2.10 × 1010 13 t, of which the proportion of petrochemical wastewater was 3.00-5.00% in 14 2016. A report derived from China’s oil and chemical industry has shown that 2.00 15 billion tons of petrochemical wastewater were produced only in 2016, and the total 16 emission increased up to 4.00 billion during the 13th 5-year plan period (CMEP, 17 2015). Moreover, massive petrochemical wastewater was produced all over the world 18 during the same period that needed to be treated properly and urgently.

The heavy metals present in sludge are very harmful to the environment and the human body. It is necessary to remove them before sludge disposal. In this study, an ex situ method for removing heavy metals from sludge using electroosmosis was designed, and experiments were conducted to study the effects of electroosmosis voltages (30 V, 40 V and 50 V), citric acid concentrations (0.03 mol/kg, 0.06 mol/kg, 0.09 mol/kg and 0.12 mol/kg) and the power supply (continuous and interrupted) on the removal rate of heavy metals (Cu, Cr, Cd, Zn and Pb). The study found that the combination of the citric acid pretreatment and electroosmosis can effectively improve the removal rate of heavy metals. An appropriate increase in the voltage and citric acid concentration can improve the removal rate of heavy metals. The best combination was determined to be 40 V and 0.09 mol/kg. Under these conditions, the removal rates of Cu, Cr, Cd, Zn and Pb, were 14.39%-41.28% (continuous power supply) and 21.78%-42.36% (interrupted power supply). The interrupted power supply effectively improved the removal rates of Cd and Zn but reduced the removal rates of Cr and Pb. The power supply mode had no significant effect on the removal rate of Cu. Heavy metal speciation was analyzed by the BCR method, and the relationship between the ratio of easily removed metal speciation and the removal rate was studied. The increase in the ratio of easily removed speciation was accompanied by an increase in the removal rate, indicating that citric acid and electroosmosis increased the removal rate by increasing the ratio of easily removed speciation. However, the high pH value around the cathode caused by the electrochemical reaction was not conducive to the removal of heavy metals.

Introduction

Sewage sludge, a byproduct of sewage treatment processes, is rich in nitrogen (N), phosphorus (P), potassium (K) and organic matter. It is a popular practice to dispose of sewage sludge via land use, and many countries currently use this method. However, it can be difficult to convince the government and land users to agree on this method because of the presence of toxic metals and bacteria in the sludge. Therefore, it is necessary to separate the heavy metals from the sludge [1,2]. The methods for the removal of heavy metals from sludge are chemical extraction, electrokinetic remediation, filtration, ion exchange, adsorption on activated carbon, membrane technologies, microbiological leaching, phytoremediation, etc. [3-9]. The electrokinetic process aims to remove the heavy metals using an electric field, which promotes several complex mechanisms such as electrodialysis electric migration, electrophoresis, and electrolysis. This approach is conducive to the transportation of pollutants [10,11]. These effects cause the heavy metals to concentrate around the cathode, which allows for their removal. The advantages of electrokinetic remediation are that it is simple (i.e., simple equipment), flexible (i.e., can be used for in situ or ex situ treatments), relatively inexpensive, effective and environmentally friendly [12,13].

The current Australian sugarcane industry transition towards adoption of an ‘alternative’ herbicide strategy as part of improved environmental stewardship is increasingly complicated by recent farming system, regulatory and herbicidal product changes. This study quantified and compared the efficacy, economic costs and environmental risk profile s of a range of established, emerging, and recently registered pre -emergent herbicides across field trials in the Wet Tropics region of North Queensland. Several herbicides were effective on certain weed species, but lacked broad spectrum control. Better efficacy results from products with multiple active ingredients (i.e., imazapic -hexazinone) demonstrated the benefits of using mixtures of active ingredients to widen the spectrum of weed control efficacy. All tested pre – emergent herbicides behaved quite similarly in terms of their propensity for off-site movement in water (surface runoff losses generally > 10 % of active applied), with their losses largely driven by their application rate . Herbicides with lower application rates consistently contributed less to the total herbicide loads measured in surface runoff. Results demonstrated alternative choices from the more environmentally problematic herbicides (such as diuron) are available with effective alternative formulations providing between 4 and 29 less risk than the traditional diuron -hexazinone ‘full rate’. However, considerable challenges still face canegrowers in making cost -effective decisions on sustainable herbicide selection. Additional research and effective grower extension are required to address information gaps in issues such as specific weed control efficacy of alternative herbicides and potential blending of some herbicides for more effective broad spectrum weed control, while also minimizing environmental risks.

Introduction

The decline of fresh and marine water quality associated with land -based runoff from adjacent agricultural catchments is a major cause of the poor state of many of the coastal ecosystems of Australia’s Great Barrier Reef (GBR) World Heritage Area (Waterhouse et al., 2017). Pesticides have been specifically identified as among the most important diffus e source pollutants from catchment areas of the GBR (Brodie et al., 2012). High value freshwater, estuarine and inshore waters of the GBR lagoon are regularly exposed to pesticide runoff from agricultural lands, particularly during wet season riverine flood events (December to April) (e.g. Lewis et al., 2009 ; Davis et al., 2012). The pesticides that have been most commonly detected in the GBR lagoon are herbicides that inhibit electron transport at photosystem II (PSII) in plants and include diuron, atrazine, hexazinone, ametryn, simazine and tebuthiuron (Haynes et al., 2000a ; Shaw and Müller, 2005 ; Shaw et al., 2010). Concentrations during elevated stream flow events can at times exceed ecological water quality protection guideline trigger values for up to several weeks for some of these PSII herbicides (Lewis et al., 2009 ; 2012 ; Brodie et al., 2012 ; Davis et al., 201 3 ; O’Brien et al., 2016; Novic et al., 2018).

1- Introduction

2- Materials and methods

3- Results and discussion

4- Conclusion

References

Abstract

Dewatering from sludge is an important sustainable issue in recent years, in this work, we found the unique behavior: Skeleton builder additions can improve the dewatering performance greatly, which related to the different pore structure of skeleton builder. As compared to the coal ash, sawdust and rice husk char are easier to construct porous channels in the sludge body, which is responsible for the discharge of water. the dewatering efficiency can increased from approximately 30%–65% by pipe network effect and interlayer channel effect, a sufficient amount of skeleton builders establish a complete pipe drainage network in the sludge body, allowing the water to be discharged fluently. Moreover, the skeleton builders can cause the sludge body to form a layered structure. Under the combined action of pipe network effect and interlayer channel effect, the deep-dewatering effect increased largely by the addition of skeleton builders.

Introduction

Environment and Energy aspects are two main topics in the world (Du et al., 2018; Zhou et al., 2018), but the waste disposal will become an important environmental issue recently, Domestic sewage treatment by bio-methods can produce a large amount of sewage sludge. The key issue of sludge treatment aims at reducing the moisture content efficiently (Ren et al., 2015; Skinner et al., 2015; Zhang et al., 2015). In order to facilitate the subsequent disposal and resource utilization, the general method of mechanical dehydration can reduce the moisture content of sludge to the level of approximately 80%, which is far below the requirements of sludge treatment (Yang et al., 2015), and thus, a deep dehydration is necessary and required. Thermal drying and sludge conditioning as well as mechanical dehydration methods are commonly used in sludge deep dewatering process. However, high energy consumption and serious secondary pollution problems will significantly inhibit its efficient application (Mahmoud et al., 2016; Tang et al., 2018; Zhang et al., 2014); therefore, efficient approach is urgent and raised a wide-spread research interests. As well known, sludge dewatering mainly contains two important procedures, that is solid-liquid separation at first, and the sequent extrusion for separation water from sludge (Christensen et al., 2015). Recent study shows that the surface adsorption water and internal hydration water can be converted into free-water by series sludge pretreatment (To et al., 2016), thence favoring for the solid-liquid separation. However, in fact, it is difficult to achieve the efficient deep dehydration, because the organic matter content of sludge floc will lead to a high compressibility, and the drainage channels in sludge body will be shut down by the high mechanical pressure during the squeeze process (Collard et al., 2017; Li et al., 2014a). Thus, a dense layer will form on the surface of the sludge body, and deep water separation cannot be discharged completely. Therefore, the use of chemical conditioning can only improve the sludge dewatering performance to some extent (Vega et al., 2015; Zhang et al., 2017c) However, because of the supporting effect of skeleton builder, the porous structure still exist in the sludge body under the great mechanical pressure, so the water can flow out of the sludge body easier. The commonly used skeleton builders by researchers are simple and easy available solid materials, such as powdered coal ash (Cieślik et al., 2015), lime (Hu et al., 2017), sawdust (Deng et al., 2017), wheat grits (Guo et al., 2015), gypsum (Nittami et al., 2015), red mud (Zhang et al., 2014), lignite (Hoadley et al., 2015), rice husk char (Wu et al., 2016b) and so on.

1- Introduction

2- Sources and characterization of agricultural wastewater

3- Struvite and its recovery performance from agricultural wastewaters

4- Commercial development of struvite products

5- Hindrances to struvite recovery from agricultural wastes

6- Strategies for performance intensification and operational cost reductions

7- Use of struvite as an alternative fertilizer in the soil

8- Economic evaluation

9- Conclusions

References

Abstract

To meet the needs of a fast growing global population, agriculture and livestock production have been intensified, resulting in environmental pollution, climate change, and soil health declining. Closing the nutrient circular loop is one of the most important sustainability factors that affect these issues. Apart from being a serious environmental issue, the discharge of N and P via agricultural wastewater is also a major factor that disturbs nutrient cycling in agriculture. In this study, the performance, in terms of recovery, of N and P (individually, as well as simultaneously) from agricultural wastewaters via struvite has been comparatively summarized. Details on the hindrances to nutrient recovery through struvite formation from agricultural effluents, along with strategies to overcome these hindrances, are provided. In addition, various strategies for recovery performance intensification and operational cost reduction are comprehensively discussed. This work will provide scientists and engineers with a better idea on how to solve the bottlenecks of this technique and integrate it successfully into their treatment systems, which will ultimately help close the nutrient loop in agriculture.

Introduction

The manifestations of rapid population growth, urbanization, improved standards of living, and concurrent intensification of socioeconomic activities on overall environmental health are well recognized and acknowledged (Cordell et al., 2009; Clarke, 2013). Global cereal production has doubled in the past 40 years, mainly from the increased yields resulting from greater inputs of fertilizer, water, pesticides, and so on. This has increased the global per capita food supply and alleviate hunger in poverty-stricken areas (Alexandratos and Bruinsma, 2012). During this process, however, the increase in nitrogenous fertilizer application and exhaustion of the limited reserves of rock phosphate have been quite considerable. At present, the annual fertilizer consumption of rock phosphate is reported to be over one million tons, while the use of N fertilizer could be three times as much (Rahman et al., 2011). Moreover, it is estimated that within 100 years, mined P rocks will be completely exhausted (Cordell and White, 2014”). Global cycling of these nutrients has been altered, owing to their widespread use in intensive agriculture, in ways that can contribute to severe environmental issues. Predominantly, nutrients can escape from farm fields to the surrounding soils, air, and waterways, when applied in excess of the plants’ needs (Deng et al., 2006). Hence, the notion of a closed-loop nutrient cycle provides a simple, persuasive, and elegant approach for realizing efficient natural resource management-improved human well-being, and long-term food security (Maurer et al., 2006). The closing of the nutrient loop includes a wide range of ongoing efforts to make sure that nutrients are applied at times and places that align with the requirements of the plants. It also includes efforts to recover nutrients in usable forms from waste effluents and recycle them into cropping systems (Yorgey, 2014). The logic is that by recovering nutrients from waste effluents, a more “closed” system for sustainable agricultural development can be created.

Introduction

Materials and method

Results and discussion

Conclusion

References

Abstract

Adsorption is one of the most commonly used methods for the wastewaters treatment. In this work, we studied the impact of experimental conditions on the adsorption of heavy metals M(II) (M=Cd, Ni, Cu, Pb and Zn) in batch system using chitin obtained from crab shells. This biomaterial is selected because of its low cost, availability and efciency. The M(II) adsorption was found to be dependent on the initial pH, contact time, initial concentration of M(II) and biomass dose. The kinetic models of Elovich, pseudo-frst-order and pseudo-second-order kinetic models were successfully applied, providing the best ftting of the experimental data. The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms and the thermodynamic parameters were also discussed. The adsorption capacity peaks at: 50, 47.61, 43.4, 40 and 38.46 (mg L−1) for Pb(II), Cu(II),Ni(II), Cd(II) and Zn(II), respectively. The negative free energy (∆G°) and positive enthalpy (∆H°) indicated spontaneous and endothermic adsorption.

Introduction

The natural environment is constantly contaminated by various pollutants coming from industrial sectors, which in turn showed a considerable change. Toxic metals are widespread and hazardous and afect the environment with a negative impact on the ecosystem, causing dangerous diseases to both animals and humans. Among toxic metals, one can cite Cd, Hg, Pb, As, Cr and Cu (Salem et al. 2012) which must be removed before discharge to the aquatic environment. Unlike organic pollutants, heavy metals are refractory and cannot be degraded and accumulate in living organisms (Ali and Ateeg 2015). The elimination of metals has been the subject of several works using diferent techniques like ion electrodialysis (Esalah et al. 2000), sedimentation (Gupta et al. 2001), ion exchange (Da̧browski et al. 2004; Kang et al. 2008), biological operations (Rashid et al. 2014), coagulation/focculation (Yue et al. 2009), nanofltration (Hafane et al. 2000), solid-phase extraction (Khezami and Capart 2005), adsorption (Abolhasani and Behbahani 2015; Behbahani et al. 2014) and electrokinetic remediation (Sawada et al. 2004). However, all these techniques sufer from high costs of capital and operations as well as the elimination of metallic sludge (Malairajan 2011). On the other hand, the adsorption has become advantageous for removing toxic metals because of its environmentally friendly characteristic, efciency and low cost. In this regard, many marine wastes were used as adsorbents for both inorganic and organic pollutants (Copat et al. 2012; Izquierdo et al. 2014; Samiey and Ashoori 2012; Vilar et al. 2008).

1- Introduction

2- Chemistry of geopolymers

3- Method and analysis section

4- Synthesis of geopolymers and mechanisms involved

5- Use of industrial waste as filler for the fabrication of crystalline metakaolin-based geopolymer

6- Result and discussion on applications driven by the surface chemistry of geopolymers in water

7- Barriers to utilization

8- Future research and prospects

9- Conclusion

References

Abstract

Geopolymer is a ceramic material, most often amorphous; finds applications in fire- and heat-resistant coatings and adhesives, medicines, refractory ceramics and binders, and manufacturing of radioactive waste container. Over the last decade, new cement based on geopolymers has been developed. Most relevant to this review is the fact that its porous nature and chemical similarity to zeolites is being employed for applications pertaining to wastewater treatment. Most of the work has been on the adsorptive treatment of water. However, using chemical reasoning and literature available we show that geopolymers have relevance for further activity on additional areas of relevance to waste water treatment such as photocatalysis, disinfection, and H2-energy production from waste water etc. These applications would depend strongly on the properties of geopolymers, which in turn would rely on the precursors employed and the synthetic methods used. The relevance of geopolymers for cleaner production is also highlighted. The use of fly ashes and metakaolin composites for the fabrication and surface tailoring of geopolymers (perhaps using relevant surfactants) is suggested as a plausible step in the right direction. Given the critical analysis of the state of the art, and the plausible directions identified, this article will benefit environmental scientists, engineers and chemists interested in deploying geopolymers for environmental remediation purposes. However moving forward, barriers are to be anticipated for the large scale implementation of geopolymers. Several barriers (e.g. legal, economical, technocrats and synthetic challenges) that are likely to hinder future research and translation are highlighted.

Introduction

Heavy metal removal and organic molecule degradation from wastewater have become a major topic of the public interest, due to their relevance to health and environment. Heavy metal and hazardous organic molecules are known to be toxic and a precursor to ill-health of the populace (Jaishankar et al., 2014). They are primarily released into the environment through human/industrial activities (Azimi et al., 2017). Hence research on multifunctional materials which relates to simultaneous environmental remediation and energy production are relevant to contemporary technologies connected with cleaner production. Geopolymers are a promising category of materials, for the removal of toxic substances from industrial and household effluents. It is usually prepared from a rather simple and eco-friendly reaction between an alkali such as NaOH/Na2SiO3 or KOH; and Al and Si source (s), making it a material amenable to clean production. Geopolymers obtained thus are often applied for the removal of metal ions such as Cs+ , Pb2+, Cd2+ etc. from wastewater. Geopolymers have come a long way, since their first discovery four decades ago (Davidovits, 1976). It has gained attention primarily because of the ease with which it can be synthesized with little or zero emission of green house gases (CO2. SO2, NOx etc.) (Noor ul et al., 2016). This coupled with its properties which include toughness, fire and heat resistance (i.e. its refractory nature), radiation hardness (making it relevant for radioactive waste containment) and pozzolanic action (Carsten, 2013), make geopolymers truly multifunctional.