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Full-Scale Floating Treatment Wetlands in Pakistan: From Performance Evaluation to Public Acceptance
Abstract
Many communities in Pakistan use unsafe water polluted by domestic or industrial activities. Water treatment infrastructure is hardly in place, while the country’s socioeconomics jeopardizes its maintenance and improvement. Especially in rural areas, any cost-effective and passive solution to improve water quality is a boon. Here we present the successful application of a full-scale floating treatment wetland (FTW) for attenuating the pollutant concentration in a crude oil wastewater pit. Floating rafts, covering about 1/3 of the pit’s water surface area (10,000 m2), were established using indigenous wetland plants. Successful removal of organics (>97%), hydrocarbons (99.6%), total dissolved solids (82%), heavy metals, and toxicity was recorded within six-months. Mass balance confirmed removal of organics up to 2.63 × 105, whereas carbon sequestration by FTW was 2.11 × 103 kg. About 500,000 m3 of wastewater received treatment at a cost of US$0.0184 per m3, which was later reduced to US$0.0033 per m3. A cross-sectional survey illuminated that application of the FTW positively impacted the lives of local communities. The FTW also became a new habitat for native bird species, thus underscoring the improved water quality and highlighting the study’s alignment with the United Nations Environment Program for better conditions for water supply and biodiversity.
... For instance, in the case of wastewater rich in crude oil content, we expanded the coverage to 33% of the pit area to meet the required standards (a batch system). 6 These parameters are adaptable and subject to alterations, contingent upon the specific type of wastewater and the prevailing local climate conditions. For a deeper grasp of the system's hydraulics, refer to the earlier study by Nivala et al. 7 When selecting plants, it's crucial to consider their tolerance to varying water conditions, such as pollutants, salinity, and pH, which can be achieved by choosing species naturally found in wetlands or marshy areas. ...
Floating treatment wetlands (FTWs) consist of buoyant rafts that support the growth of macrophytes on waterbodies. The long-term performance of these rafts depends on their buoyancy and resistance to weathering. Here, we present a protocol for establishing low-cost FTWs for large-scale wastewater reclamation by integrating traditional ecological knowledge with modern engineering principles. We describe steps for setting up a plant nursery, designing and establishing the FTWs, vegetating units, and building the FTW island.
For complete details on the use and execution of this protocol, please refer to Afzal et al. (2019)
As a direct consequence of extreme monsoon rainfall throughout the summer 2022 season Pakistan experienced the worst flooding in its history. We employ a probabilistic event attribution methodology as well as a detailed assessment of the dynamics to understand the role of climate change in this event. Many of the available state-of-the-art climate models struggle to simulate these rainfall characteristics. Those that pass our evaluation test generally show a much smaller change in likelihood and intensity of extreme rainfall than the trend we found in the observations. This discrepancy suggests that long-term variability, or processes that our evaluation may not capture, can play an important role, rendering it infeasible to quantify the overall role of human-induced climate change. However, the majority of models and observations we have analysed show that intense rainfall has become heavier as Pakistan has warmed. Some of these models suggest climate change could have increased the rainfall intensity up to 50%. The devastating impacts were also driven by the proximity of human settlements, infrastructure (homes, buildings, bridges), and agricultural land to flood plains, inadequate infrastructure, limited ex-ante risk reduction capacity, an outdated river management system, underlying vulnerabilities driven by high poverty rates and socioeconomic factors (e.g. gender, age, income, and education), and ongoing political and economic instability. Both current conditions and the potential further increase in extreme peaks in rainfall over Pakistan in light of anthropogenic climate change, highlight the urgent need to reduce vulnerability to extreme weather in Pakistan.
Background
Universal access to safe drinking water and sanitation facilities is an essential human right, recognised in the Sustainable Development Goals as crucial for preventing disease and improving human wellbeing. Comprehensive, high-resolution estimates are important to inform progress towards achieving this goal. We aimed to produce high-resolution geospatial estimates of access to drinking water and sanitation facilities.
Methods
We used a Bayesian geostatistical model and data from 600 sources across more than 88 low-income and middle-income countries (LMICs) to estimate access to drinking water and sanitation facilities on continuous continent-wide surfaces from 2000 to 2017, and aggregated results to policy-relevant administrative units. We estimated mutually exclusive and collectively exhaustive subcategories of facilities for drinking water (piped water on or off premises, other improved facilities, unimproved, and surface water) and sanitation facilities (septic or sewer sanitation, other improved, unimproved, and open defecation) with use of ordinal regression. We also estimated the number of diarrhoeal deaths in children younger than 5 years attributed to unsafe facilities and estimated deaths that were averted by increased access to safe facilities in 2017, and analysed geographical inequality in access within LMICs.
Findings
Across LMICs, access to both piped water and improved water overall increased between 2000 and 2017, with progress varying spatially. For piped water, the safest water facility type, access increased from 40·0% (95% uncertainty interval [UI] 39·4–40·7) to 50·3% (50·0–50·5), but was lowest in sub-Saharan Africa, where access to piped water was mostly concentrated in urban centres. Access to both sewer or septic sanitation and improved sanitation overall also increased across all LMICs during the study period. For sewer or septic sanitation, access was 46·3% (95% UI 46·1–46·5) in 2017, compared with 28·7% (28·5–29·0) in 2000. Although some units improved access to the safest drinking water or sanitation facilities since 2000, a large absolute number of people continued to not have access in several units with high access to such facilities (>80%) in 2017. More than 253 000 people did not have access to sewer or septic sanitation facilities in the city of Harare, Zimbabwe, despite 88·6% (95% UI 87·2–89·7) access overall. Many units were able to transition from the least safe facilities in 2000 to safe facilities by 2017; for units in which populations primarily practised open defecation in 2000, 686 (95% UI 664–711) of the 1830 (1797–1863) units transitioned to the use of improved sanitation. Geographical disparities in access to improved water across units decreased in 76·1% (95% UI 71·6–80·7) of countries from 2000 to 2017, and in 53·9% (50·6–59·6) of countries for access to improved sanitation, but remained evident subnationally in most countries in 2017.
Interpretation
Our estimates, combined with geospatial trends in diarrhoeal burden, identify where efforts to increase access to safe drinking water and sanitation facilities are most needed. By highlighting areas with successful approaches or in need of targeted interventions, our estimates can enable precision public health to effectively progress towards universal access to safe water and sanitation.
Globally, water resources contaminated with petroleum hydrocarbons are under much consideration due to their hazardous effects on human beings as well as on plants and animals in the ecosystem. Petroleum hydrocarbons are classified as recalcitrant pollutants in nature. These petroleum products are mostly released in the water resources during the petroleum refining process by oil refineries. The conventional clean-up technologies for hydrocarbons contaminated water have more destructive effects on the aquatic and land ecosystems. Consequently, to develop cost-effective and more environment-friendly techniques that clean up the environment and restore the marine ecosystem to its original forms. Keeping in view, this review article explores the detailed information on fabrication, cost-effectiveness, and an overview of innovation of the floating treatment wetlands (FTWs) using plants and bacterial combined functions to remediate the petroleum hydrocarbons contaminated water. The review also discusses the improvement of microbial efficacy for hydrocarbon degradation using FTWs. The review article shows the various applications of FTWs to remove different organic pollutants in petroleum hydrocarbons contaminated water. The review also describes the prospective benefits of FTWs for their multiple uses for removal of hydrocarbons, chemical oxygen demand (COD), biochemical oxygen demand (BOD), phenol, and solids from hydrocarbons contaminated water. This review widely discusses the role of hydrocarbons in degrading bacteria, and wetland plants and the mechanism involved during the remediation process of hydrocarbons in FTWs. It further demonstrates features disturbing the treatment efficiency of FTWs, and finally, it is concluded by successful applications of FTWs and various suggestions for potential future research prospects.
Graphical Abstract
The most significant investment in improved water governance for Pakistan in recent decades—irrigation management transfer under the PIDA Act of 1997—ended with repeal in 2019 in the province of Punjab. Before embarking on the next major experiment, we wish to examine what the opportunity space for improvement in Pakistan’s water governance is. We develop a conceptual model that maps the roles of hydrology, infrastructure, management, governance, and learning in shaping water supply. We are motivated by the overarching question of where the best opportunities to improve water governance in Pakistan lie, and suggest in our analysis that the hydraulic constraints of the Indus Basin Irrigation System (IBIS) that have previously been the basis for consideration of scale in water (irrigation) governance are inappropriate. Our key recommendation is instead to identify the key “problemsheds” for the IBIS as a vehicle for identifying scales of intervention and communities of common water interest (possibly at village, union, or tehsil administrative levels) that can allow irrigators to transcend the rigid hydraulic user groupings that irrigation channels impose, and contribute more meaningfully to good local water governance.
Significance
Despite growing evidence of the deleterious effects on ecological and human health, little is known regarding the global occurrence of pharmaceuticals in rivers. Studies assessing their occurrence are available for 75 of 196 countries, with most research conducted in North America and Western Europe. This leaves large geographical regions relatively unstudied. Here, we present the findings of a global reconnaissance of pharmaceutical pollution in rivers. The study monitored 1,052 sampling sites along 258 rivers in 104 countries of all continents, thus representing the pharmaceutical fingerprint of 471.4 million people. We show that the presence of these contaminants in surface water poses a threat to environmental and/or human health in more than a quarter of the studied locations globally.
The use of constructed wetlands (CWs) is a promising approach for the remediation of hydrocarbon-polluted wastewater. The amendments of CWs with nutrients, surfactants, and aeration enhances the removal of pollutants from wastewater. The objective of the present study was to explore the effect of external stimulants, i.e., nutrients, surfactant, and aeration on hydrocarbons degradation potential of CWs. The CWs mesocosms were developed by the vegetation of Phragmites australis and amendments with nutrients (20 mg l⁻¹ N, 2.6 mg l⁻¹ P, and 16.4 mg l⁻¹ K), surfactant Tween 20 (0.2%, v/v), and aeration (7 mg l⁻¹) for the remediation of diesel-spiked water (2%, w/v). The comparative analysis showed that the addition of nutrients, surfactant, and aeration individually enhanced total petroleum hydrocarbons (TPHs) reduction, and maximum TPHs reduction (88.4%) was achieved after 60 days in the mesocosms amended with the combination of nutrients, surfactant, and aeration. Among different individual treatments, the aeration (alone) also played a pivotal role in TPHs reduction (61%). The least (12%) reduction in TPHs was achieved in the mesocosms supplied with surfactant only. This study revealed that the combined application of nutrients, surfactant, and aeration in CWs enhanced its hydrocarbons degradation performance.
This study examines the relationship of drinking water sources with the consequential health issues in children regarding incidence and prevalence of waterborne diseases like, Typhoid, Cholera, Hepatitis A & E, Diarrhea Dermatitis and Worm infestation in Shah di Khoi, Lahore, Pakistan. Primary data sources such as drinking water samples, and questionnaire field survey were used to examine the pollution of drinking water and its health effects upon children aging less than 5 years. The field survey was conducted from June to August 2018 and 350 households were visited in the study area and were inquired about their sources of drinking water, water quality related issues and any prevalence of waterborne disease among children during the survey period. The common drinking water sources were local bore water and water fetched from filtration plants. Water samples were collected from the households where sick children were found and were tested for physical parameters including pH value, total hardness, total dissolved solids and electrical conductivity; and microbiological parameters such as total coliforms and Escherichia coli. The results of tested water samples for physical parameters were found well within the permissible ranges of the World Health Organization (WHO) standards. However, microbial contamination was found in few samples of local bore water and filtration plant. The most common diseases found in children were Cholera, Diarrhea, Typhoid, Hepatitis A and E, etc. The field observations confirm that most of the drinking sources were affected by bacterial contamination and was resulting in the incidence of waterborne infections among children in the study area. This study suggests for future laboratory investigations to assess the water quality, and to correlate waterborne diseases to responsible factors on larger scale through geospatial maps using modern techniques based on Remote Sensing (RS) and Geographical Information System (GIS). This will also help determine other environmental factors playing role in the disease incidence within the region and surrounding areas.
The devastations and damages caused by climate change are apparent across the globe, specifically in the South Asian region where vulnerabilities to climate change among residents are high and climate change adaptation and mitigation awareness are extremely low. Pakistan’s low adaptive capacity due to high poverty rate, limited financial resources and shortage of physical resources, and continual extreme climatic events including varying temperature, continual flooding, melting glaciers, saturation of lakes, earthquakes, hurricanes, storms, avalanches, droughts, scarcity of water, pest diseases, human healthcare issues, seasonal and lifestyle changes, have persistently threatened the ecosystem, biodiversity, human communities, animal habitations, forests, lands and oceans with a potential to cause further damages in future. The likely effect of climate change on common residents of Pakistan with comparison to the world and their per capita impact of climate change are terribly high with local animal species such as lions, vultures, dolphins, and tortoise facing extinction regardless of generating and contributing diminutively in global GHG emissions. The findings of the review suggested that GHG emissions have impacted agriculture livestock & forestry, weather trends, and patterns, food water & energy security, and society of Pakistan.This review is a sectorial evaluation of climate change mitigation and adaption approaches in Pakistan in the aforementioned sectors and its economic costs which were identified to be between 7 to 14 billion USD per annum. The research suggested that governmental interference is essential for the sustainable development of the country through strict accountability of resources and regulation implemented in the past for generating state-of-the-art climate policy.
In many developing countries, there are limited or insufficient wastewater treatment infrastructures. Floating treatment wet-lands (FTWs) can be a cost-effective phytoremediation approach to treat various types of wastewater. The buoyancy of the FTWs is due to air-filled rhizomes and entrapment of gas bubbles by the interwoven roots, which can be supported further by rafts. The performance of full-scale systems for treating genuine wastewater is largely unknown because studies so far have been experimental. Here, we installed full-scale FTWs in stabilization ponds receiving sewage (60%) and industrial (40%) wastewater from Faisalabad, Pakistan, and evaluated their treatment performance over a period of three years. The FTWs promoted a substantial improvement of all recorded water quality indicators and a reduction of heavy metal concentrations in the effluent compared to the influent. The maximum removal capacities of the system were 79% of chemical oxygen demand (COD), 88% of biochemical oxygen demand (BOD) and 65% of total dissolved solids (TDS). The performance was optimal in the second and third years of operation during which about 60 million m3 per year of wastewater was treated at a cost of US$0.00026 per m3. This study demonstrates that FTWs are an appropriate ecotechnology for the large-scale cleanup of sew-age and industrial wastewater.
Organic carbon stored in coastal wetlands, which comprises the major part of oceanic “blue carbon,” is a subject of growing interest and concern. In this study, organic carbon storage in coastal wetlands and its economic value were estimated using the raw data of 25 studies related to soil carbon storage. Data were collected from three tidal flats (one protected and two developed areas) and two estuarine salt marshes (one protected and one restored area). Bulk density, soil organic matter content, and standing biomass of vegetation were all considered, with Monte Carlo simulation applied to estimate the uncertainty. Mean carbon storage in two salt marshes ranged between 14.6 and 25.5 kg C m−2. Mean carbon storage in tidal flats ranged from 18.2 to 28.6 kg C m−2, with variability possibly related to soil texture. The economic value of stored carbon was estimated by comparison with the price of carbon in the emission trading market. The value of US $6600 ha−1 is ~ 45% of previously estimated ecosystem services from fishery production and water purification functions in coastal areas. Although our study sites do not cover all types of large marine ecosystem, this study highlights the substantial contribution of coastal wetlands as carbon sinks and the importance of conserving these habitats to maximize their ecosystem services.
This paper examines the processes of formulation of UN Sustainable Development Goal 12 (SDG 12) – ‘Ensure Sustainable Consumption and Production Patterns’ – and its targets and indicators. We argue that business interests have steered its narrative of sustainable growth. The outcome of the SDG 12 negotiations reflects a production‐ and design‐centered perspective that emerged in the 1990s and has a business‐friendly regulatory approach and faith in solutions through new technologies. We show how the targets and indicators emerged in debates between national governments, UN agencies, civil society and private sector organizations – and how they reflect both the political process and technical and practical considerations in translation of a broad concept into the SDG format. While the emergence of SDG 12 as a standalone goal stems from a push by developing countries to build pressure on developed countries, and its presence may open space for attention to this area in the future, many of its targets were watered down and left vague. The indicators to measure progress on the targets further narrow the scope and ambition of Goal 12, whose current content does not adequately reflect earlier more transformative conceptualizations of Sustainable Consumption and Production. Most of the targets under SDG 12 do not yet have satisfactory indicators. Enunciation of the targets may yet spur further work and real actions.
The contamination of water with hydrocarbons resulting from oil exploration and production highlights the need for efficient and environmentally friendly technology to mitigate this form of water pollution. Floating treatment wetlands are a sustainable approach for remediating contaminated water. In this large-scale study, we used four different plants, Phragmites australis, Typha domingensis, Leptochloa fusca, and Brachiaria mutica, to vegetate a floating mat with an area of 3058 m2 made from locally sourced materials. The floating treatment wetlands constructed in this manner were used to treat an oil-contaminated water stabilization pit resulting from oil and gas exploration activities in District Chakwal, Pakistan. The plants and the water in the pit were inoculated with a consortium of 10 different hydrocarbon-degrading bacteria. The application of floating treatment wetlands to the pit reduced chemical oxygen demand, biochemical oxygen demand, total dissolved solids, hydrocarbon content, and heavy metals by 97.4%, 98.9%, 82.4%, 99.1%, and 80%, respectively, within 18 months. All plants survived and showed growth, but maximum development and biomass production were exhibited by P. australis. Moreover, the bacteria used for inoculation were able to persist and show degradation activity in the water as well as in the rhizoplane, roots, and shoots of the plants. We conclude that floating treatment wetlands can be applied to oil-contaminated water stabilization pits for affordable and effective water treatment.
Floating treatment wetland (FTW) is an effective, and sustainable technology for wastewater treatment. It has been widely adopted for treating various kinds of polluted water including agricultural runoff, stormwater, industrial effluents, etc. In FTWs, plants are vegetated on a floating mat while their roots are extended down to the contaminated water acting as biological filters. Nutrients and potentially toxic metal(s)/element(s) are taken up from the wastewater by plants through their roots whereas organic matter is degraded by the microorganisms forming biofilms on the roots and mat surface. Additionally, organic contaminants which are already taken up by the plants are degraded by endophytic bacteria in planta. This article provides an overview of FTWs and its application for wastewater treatment. The key factors which have an impact on the performance of FTWs are also described. Lastly, potential role of combined use of plants and bacteria in FTWs for the maximum remediation of polluted water is emphasized.
The economic development-environmental protection dichotomy is an out-dated construct. A 21st century approach to the world's water problems is progressively being developed by researchers and practitioners, who are combining traditional and ecosystem-based engineering systems to yield cost-effective solutions. Given the continuing and widespread loss of ecological services and functions, water security in a multi-generational, SDG context requires a meaningful, global commitment to redirect the current downward trajectory in both (i) the state of the world's ecosystems and the services they provide to society, and (ii) our collective level of stewardship of these important resources. Achieving sustainable water security will require overcoming strategic challenges related to protected areas, ecosystem-based solutions research, water observatories and expanded technical readiness. It also needs to address other limitations and demands related to water infrastructure, economies, human settlements and water quality, sanitation and health. Four globally significant actions can support the adoption of more efficient and sustainable water futures: green infrastructure watershed banks, an accelerated global research and solutions program, a new global water-ecosystem services observatory, and an improved technical capacity/workforce development initiative. Finally, the engagement of relevant stakeholders from academia, government, the private sector and civil society are needed to ensure that humankind will be able to meet its water security goals and commitments, including those expressed in the sustainable development agenda.
Helophytic plants contribute significantly in phytoremediation of a variety of pollutants due to their physiological or biochemical mechanisms. Phenol, which is reported to have negative/deleterious effects on plant metabolism at concentrations higher than 500 mg/L, remains hard to be removed from the environmental compartments using conventional phytoremediation procedures. The present study aims to investigate the feasibility of using P. australis (a helophytic grass) in combination with three bacterial strains namely Acinetobacter lwofii ACRH76, Bacillus cereus LORH97, and Pseudomonas sp. LCRH90, in a floating treatment wetland (FTW) for the removal of phenol from contaminated water. The strains were screened based on their phenol degrading and plant growth promoting activities. We found that inoculated bacteria were able to colonize in the roots and shoots of P. australis, suggesting their potential role in the successful removal of phenol from the contaminated water. The removal rate was significantly high when compared with the individual partners, i.e., plants and bacteria separately. The plant biomass, which was drastically reduced in the presence of phenol, recovered significantly with the inoculation of bacterial consortia. Likewise, highest reduction in chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total organic carbon (TOC) is achieved when both plants and bacteria were employed. The study, therefore, suggests that P. australis in combination with efficient bacteria can be a suitable choice to FTWs for phenol-degradation in water.
Arsenic-contaminated aquifers are currently estimated to affect ~150 million people around the world. However, the full extent of the problem remains elusive. This is also the case in Pakistan, where previous studies focused on isolated areas. Using a new data set of nearly 1200 groundwater quality samples throughout Pakistan, we have created state-of-the-art hazard and risk maps of arsenic-contaminated groundwater for thresholds of 10 and 50 μg/liter. Logistic regression analysis was used with 1000 iterations, where surface slope, geology, and soil parameters were major predictor variables. The hazard model indicates that much of the Indus Plain is likely to have elevated arsenic concentrations, although the rest of the country is mostly safe. Unlike other arsenic-contaminated areas of Asia, the arsenic release process in the arid Indus Plain appears to be dominated by elevated-pH dissolution, resulting from alkaline topsoil and extensive irrigation of unconfined aquifers, although pockets of reductive dissolution are also present. We estimate that approximately 50 million to 60 million people use groundwater within the area at risk, with hot spots around Lahore and Hyderabad. This number is alarmingly high and demonstrates the urgent need for verification and testing of all drinking water wells in the Indus Plain, followed by appropriate mitigation measures.
Due to alarming increase in population and rapid industrialization, drinking water quality is being deteriorated day by day in Pakistan. This review sums up the outcomes of various research studies conducted for drinking water quality status of different areas of Pakistan by taking into account the physicochemical properties of drinking water as well as the presence of various pathogenic microorganisms. About 20% of the whole population of Pakistan has access to safe drinking water. The remaining 80% of population is forced to use unsafe drinking water due to the scarcity of safe and healthy drinking water sources. The primary source of contamination is sewerage (fecal) which is extensively discharged into drinking water system supplies. Secondary source of pollution is the disposal of toxic chemicals from industrial effluents, pesticides, and fertilizers from agriculture sources into the water bodies. Anthropogenic activities cause waterborne diseases that constitute about 80% of all diseases and are responsible for 33% of deaths. This review highlights the drinking water quality, contamination sources, sanitation situation, and effects of unsafe drinking water on humans. There is immediate need to take protective measures and treatment technologies to overcome unhygienic condition of drinking water supplies in different areas of Pakistan.
Hydroponic root mats (HRMs) are ecotechnological wastewater treatment systems where aquatic vegetation forms buoyant filters by their dense interwoven roots and rhizomes, sometimes supported by rafts or other floating materials. A preferential hydraulic flow is created in the water zone between the plant root mat and the bottom of the treatment system. When the mat touches the bottom of the water body, such systems can also function as HRM filter; i.e. the hydraulic flow passes directly through the root zone. HRMs have been used for the treatment of various types of polluted water, including domestic wastewater; agricultural effluents; and polluted river, lake, stormwater and groundwater and even acid mine drainage. This article provides an overview on the concept of applying floating HRM and non-floating HRM filters for wastewater treatment. Exemplary performance data are presented, and the advantages and disadvantages of this technology are discussed in comparison to those of ponds, free-floating plant and soil-based constructed wetlands. Finally, suggestions are provided on the preferred scope of application of HRMs.
Plant-bacteria partnership is a promising strategy for the remediation of soil and water polluted with hydrocarbons. However, the limitation of major nutrients (N, P and K) in soil affects the survival and metabolic activity of plant associated bacteria. The objective of this study was to explore the effects of nutrients on survival and metabolic activity of an alkane degrading rhizo-bacterium. Annual ryegrass (Lolium multiflorum) was grown in diesel-contaminated soil and inoculated with an alkane degrading bacterium, Pantoea sp. strain BTRH79, in greenhouse experiments. Two levels of nutrients were applied and plant growth, hydrocarbon removal, and gene abundance and expression were determined after 100 days of sowing of ryegrass. Results obtained from these experiments showed that the bacterial inoculation improved plant growth and hydrocarbon degradation and these were further enhanced by nutrients application. Maximum plant biomass production and hydrocarbon mineralization was observed by the combined use of inoculum and higher level of nutrients. The presence of nutrients in soil enhanced the colonization and metabolic activity of the inoculated bacterium in the rhizosphere. The abundance and expression of CYP153 gene in the rhizosphere of ryegrass was found to be directly associated with the level of applied nutrients. Enhanced hydrocarbon degradation was associated with the population of the inoculum bacterium, the abundance and expression of CYP153 gene in the rhizosphere of ryegrass. It is thus concluded that the combination between vegetation, inoculation with pollutant-degrading bacteria and nutrients amendment was an efficient approach to reduce hydrocarbon contamination.
This review presents the status of phytoremediation technologies with particular emphasis on phytoextraction of soil heavy metal contamination. Unlike organic compounds, metals cannot be degraded, and cleanup usually requires their removal. Most of the conventional remedial technologies are expensive and inhibit the soil fertility; this subsequently causes negative impacts on the ecosystem. Phytoremediation is a cost effective, environmental friendly, aesthetically pleasing approach most suitable for developing countries. Despite this potential, phytoremediation is yet to become a commercially available technology in India. This paper reports about the mobility, bioavaliability and plant response to presence of soil heavy metals. It classifies the plants according to phytoextraction mechanism and discusses the pathway of metal in plants. Various techniques to enhance phytoextraction and utilization of by-products have been elaborated. Since lot of biomass is produced during this process, it needs proper disposal and management. It also gives an insight into the work done by authors, which focuses on high biomass extractor plants. High biomas weeds were selected to restrict the passage of contaminants into the food chain by selecting non-edible, disease resistant and tolerant plants, which can provide renewable energy. Thus making phytoextraction more viable for present utilization. Keywords. heavy metals, phytoextraction, hyperaccumulator, indicator, excluder species
Water pollution is one of the major threats to public health in Pakistan. Drinking water quality is poorly managed and monitored. Pakistan ranks at number 80 among 122 nations regarding drinking water quality. Drinking water sources, both surface and groundwater are contaminated with coliforms, toxic metals and pesticides throughout the country. Various drinking water quality parameters set by WHO are frequently violated. Human activities like improper disposal of municipal and industrial effluents and indiscriminate applications of agrochemicals in agriculture are the main factors contributing to the deterioration of water quality. Microbial and chemical pollutants are the main factors responsible exclusively or in combination for various public health problems. This review discusses a detailed layout of drinking water quality in Pakistan with special emphasis on major pollutants, sources of pollution and the consequent health problems. The data presented in this review are extracted from various studies published in national and international journals. Also reports released by the government and non-governmental organizations are included.
Among the 17 United Nations Sustainable Development Goals (SDGs), SDG #11 aims to make future cities resilient and sustainable while, SDG #6 aims to ensure availability and sustainable management of water and sanitation for all. In this study, the following five attributes for assessing wastewater infrastructure that can support sustainable cities are distilled from the targets set for SDG #11, #6 and other wastewater-related SDGs: reuse-quality water recovery; safe pathogen reduction; energy use and recovery in wastewater treatment; biofertilizer recovery from wastewater; and emission reduction in wastewater treatment. A total of 36 process parameters are derived to quantify these five attributes. Application of this sustainability-based approach in evaluating an emergent algal-based sewage treatment and resource recovery (STaRR) system against the traditional activated sludge-base sewage treatment practices is presented. This study emphasizes the contribution and the influence of wastewater infrastructures for the sustainability of cities and suggests that the emergent STaRR system is a sustainable pathway to provide wastewater utility service to future cities and to accomplish UN SDGs and targets.
In developing countries, one of the most severe modern-day dilemmas is the management of industrial wastewater. In these countries, industrial wastewater effluents are directly discharged into the natural drain, a sewer system, an internal septic tank or a nearby field. Some of these industrial wastewater effluents are inadequately treated or untreated before being discharged. In recent years, in developing countries, urbanization and industrial activities have led to environmental deterioration. This paper was designed to review the health and environmental impacts of inadequately treated or untreated industrial wastewater effluents in Pakistan. The quality of industrial wastewater effluents is responsible for the degradation of the receiving water bodies. This is due to the reason that inadequately treated or untreated industrial wastewater effluents may cause eutrophication in the receiving water bodies and also form a favorable condition for toxin-producing waterborne pathogens. In order to comply with the wastewater guidelines and legislations, there is a need for proper treatment before discharge. In order to minimize the risk to the environment and public health, there is a need for proper treatment processes for industrial wastewater effluents. To achieve unpolluted discharge of industrial wastewater into the receiving water bodies, regular monitoring, proper and suitable treatment, careful planning and appropriate legislation are recommended.
The aim of the present study was to investigate the potential of plant-bacterial synergism in floating treatment wetlands (FTWs) for efficient remediation of an oil field wastewater. Two plants, Brachiara mutica and Phragmites australis, were vegetated on floatable mats to develop FTWs, and inoculated with bacterial cons which were then inoculated with a consortium of hydrocarbon-degrading bacteria (Bacillus subtilis strain LORI66, Klebsiella sp. strain LCRI87, Acinetobacter Junii strain TYRH47, Acinetobacter sp. strain LCRH81). Both plants successfully removed organic and inorganic pollutants from wastewater, but bioaugmentation of P. australis significantly enhanced the plant's efficiency to reduce oil content (97%), COD (93%), and BOD (97%), in wastewater. Analysis of alkane-degrading gene (alkB) abundance and its expression profile further validated a higher microbial growth and degradation activity in water around P. australis as well as its roots and shoots. This study provides insight into the available phytotechnology for remediation of crude oil-contaminated water and introduces a wetland macrophyte, P. australis, with tailor-made bacterial consortium as an effective tool for improved phytoremediation efficiency of FTWs.
Constructed wetlands have been used for wastewater treatment for more than fifty years. Most applications have been designed to treat municipal or domestic wastewater but at present, constructed wetlands are successfully applied to many types of wastewater. The early constructed wetlands applied to industrial wastewaters included those for wastewaters from petrochemical, abattoir, meat processing, dairy and pulp and paper industries. During the 1990s constructed wetlands were also used to treat effluents from textile and wine industries or water from recirculating fish and shrimp aquacultures. The most recent applications include those for brewery or tannery wastewaters as well as olive mills effluents. The survey revealed that both subsurface and surface flow constructed wetlands have been used for treatment of industrial wastewaters. Within subsurface flow constructed wetlands both horizontal and vertical flow systems have been designed. Also, the use of various hybrid constructed wetlands for industrial effluent treatment has been reported in the literature recently. The survey also revealed that industrial wastewaters are treated in constructed wetlands in all continents and this paper includes the information from 138 constructed wetlands in 33 countries worldwide.
The combined use of plants and associated microorganisms has great potential for cleaning up soils contaminated with petroleum hydrocarbons. Apart from environmental conditions the physicochemical properties of the soil are the main factors influencing the survival and activity of an inoculated strain as well as the growth of plants. This study examined the effect of different soil types (sandy, loamy sand and loam) on the survival, gene abundance and catabolic gene expression of two inoculated strains (Pseudomonas sp. strain ITRI53 and Pantoea sp. strain BTRH79) in the rhizosphere and shoot interior of Italian ryegrass vegetated in diesel contaminated soils. High colonization, gene abundance and expression in loamy soils were observed. By contrast, low colonization, gene abundance and absence of gene expression in sandy soil were found. The highest levels of genes expression and hydrocarbon degradation were seen in loamy soil that had been inoculated with BTRH79 and were significantly higher compared to those in other soils. A positive correlation was observed between gene expression and hydrocarbon degradation indicating that catabolic gene expression is necessary for contaminant degradation. These results suggest that soil type influences the bacterial colonization and microbial activities and subsequently the efficiency of contaminant degradation.
Although many plant-associated bacteria have beneficial effects on their host, their importance during plant growth and development is still underestimated. A better understanding of their plant growth-promoting mechanisms could be exploited for sustainable growth of food and feed crops, biomass for biofuel production and feedstocks for industrial processes. Such plant growth-promoting mechanisms might facilitate higher production of energy crops in a more sustainable manner, even on marginal land, and thus contribute to avoiding conflicts between food and energy production. Furthermore, because many bacteria show a natural capacity to cope with contaminants, they could be exploited to improve the efficiency of phytoremediation or to protect the food chain by reducing levels of agrochemicals in food crops.
Water, sanitation and hygiene services in Pakistan
- R Cooper
Cooper, R. Water, sanitation and hygiene services in Pakistan.
Pakistan Institute of Development Economics
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