Municipal wastewater treatment with pond technology : historical review and future outlook

Facing an unprecedented population growth, it is difficult to overstress the assets for wastewater treatment of waste stabilization ponds (WSPs), i.e. high removal efficiency, simplicity, and low cost, which have been recognized by numerous scientists and operators. However, stricter discharge standards, changes in wastewater compounds, high emissions of greenhouse gases, and elevated land prices have led to their replacements in many places. This review aims at delivering a comprehensive overview of the historical development and current state of WSPs, and providing further insights to deal with their limitations in the future. The 21st century is witnessing changes in the way of approaching conventional problems in pond technology, in which WSPs should no longer be considered as a low treatment technology. Advanced models and technologies have been integrated for better design, control, and management. The roles of algae, which have been crucial as solar-powered aeration, will continue being a key solution. Yet, the separation of suspended algae to avoid deterioration of the effluent remains a major challenge in WSPs while in the case of high algal rate pond, further research is needed to maximize algal growth yield, select proper strains, and optimize harvesting methods to put algal biomass production in practice. Significant gaps need to be filled in understanding mechanisms of greenhouse gas emission, climate change mitigation, pond ecosystem services, and the fate and toxicity of emerging contaminants. From these insights, adaptation strategies are developed to deal with new opportunities and future challenges

Opportunities and challenges for the sustainability of lakes and reservoirs in relation to the sustainable development goals (SDGs)

Emerging global threats, such as biological invasions, climate change, land use intensification, and water depletion, endanger the sustainable future of lakes and reservoirs. To deal with these threats, a multidimensional view on the protection and exploitation of lakes and reservoirs is needed. The holistic approach needs to contain not just the development of economy and society but also take into account the negative impacts of this growth on the environment, from that, the balance between the three dimensions can be sustained to reach a sustainable future. As such, this paper provides a comprehensive review on future opportunities and challenges for the sustainable development of lakes and reservoirs via a critical analysis on their contribution to individual and subsets of the Sustainable Development Goals (SDGs). Currently, lakes and reservoirs are key freshwater resources. They play crucial roles in human societies for drinking water provision, food production (via fisheries, aquaculture, and the irrigation of agricultural lands), recreation, energy provision (via hydropower dams), wastewater treatment, and flood and drought control. Because of the (mostly) recent intensive exploitations, many lakes and reservoirs are severely deteriorated. In recent years, physical (habitat) degradation has become very important while eutrophication remains the main issue for many lakes and ponds worldwide. Besides constant threats from anthropogenic activities, such as urbanization, industry, aquaculture, and watercourse alterations, climate change and emerging contaminants, such as microplastics and antimicrobial resistance, can generate a global problem for the sustainability of lakes and reservoirs. In relation to the SDGs, the actions for achieving the sustainability of lakes and reservoirs have positive links with the SDGs related to environmental dimensions (Goals 6, 13, 14, and 15) as they are mutually reinforcing each other. On the other hand, these actions have direct potential conflicts with the SDGs related to social and economic dimensions (Goals 1, 2, 3 and 8). From these interlinkages, we propose 22 indicators that can be used by decision makers for monitoring and assessing the sustainable development of lakes and reservoirs

Electromgnetic-gravitational cross-sections in external elctromagnetic fields

The classical processes: the conversion of photons into gravitons in the static electromagnetic fields are considered by using Feynman perturbation techniques. The differential cross sections are presented for the conversion in the electric field of the flat condesor and the magnetic field of the selenoid. A numerical evaluation shows that the cross sections may have the observable value in the present technical scenario.Comment: 11 pages, LATEX, no figure

Real-time Optimal Resource Allocation for Embedded UAV Communication Systems

We consider device-to-device (D2D) wireless information and power transfer systems using an unmanned aerial vehicle (UAV) as a relay-assisted node. As the energy capacity and flight time of UAVs is limited, a significant issue in deploying UAV is to manage energy consumption in real-time application, which is proportional to the UAV transmit power. To tackle this important issue, we develop a real-time resource allocation algorithm for maximizing the energy efficiency by jointly optimizing the energy-harvesting time and power control for the considered (D2D) communication embedded with UAV. We demonstrate the effectiveness of the proposed algorithms as running time for solving them can be conducted in milliseconds.Comment: 11 pages, 5 figures, 1 table. This paper is accepted for publication on IEEE Wireless Communications Letter

Links and trade-offs between fisheries and environmental protection in relation to the sustainable development goals in Thailand

The fisheries sector significantly contributes to global food security, nutrition, and livelihood of people. Its importance for economic benefits, healthy diets, and nutrition, and achieving sustainable food systems is highlighted by several Sustainable Development Goals (SDGs), i.e., SDG 1 (No Poverty), SDG 2 (Zero Hunger), and SDG 14 (Life Below Water). However, due to unprecedented population levels, the contribution of the fisheries sector to fulfills these roles is challenging, particularly given additional concerns regarding environmental well-being and sustainability. From this perspective, this study aims to identify the links and trade-offs between the development of this sector and the environmental sustainability in Thailand via a critical analysis of their trends, current ecological impacts, and more importantly, their contributions to several individual SDGs. A time-series of Thailand's fisheries production from 1995 to 2015 indicates a recent reduction from around 3.0 million tons in 1995 to 1.5 million tons in 2015 of wild fish and shellfish from marine and freshwater habitats. The maximum sustainable yield of these species has been exceeded. Conversely, Thailand's aquaculture production has continued to grow over the last decade, resulting in a reduction of mangrove forest area, wild fish stocks, and water quality. While capture fisheries and aquaculture production significantly contribute to several SDG targets, there are potential trade-offs between their development and the achievement of SDGs within the planet dimension, i.e., SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), SDG 14, and SDG 15 (Life on Land). On the one hand, the mitigation of overfishing will be beneficial for the targets of SDG 14, leading to more sustainable resource management. On the other hand, it might cause a decrease in the volume of marine catches and economic and social profits. We conclude that the SDGs can serve as a framework for both policymakers and industrial workers to monitor and compromise on regulations that will optimize productivity in the context of sustainable development

Aquaculture production and its environmental sustainability in Thailand : challenges and potential solutions

Though aquaculture plays an important role in providing foods and healthy diets, there are concerns regarding the environmental sustainability of prevailing practices. This study examines the trends and changes in fisheries originating from aquaculture production in Thailand and provides insights into such production’s environmental impacts and sustainability. Together with an extensive literature review, we investigated a time series of Thai aquaculture production data from 1995 to 2015. Overall, Thai aquaculture production has significantly increased during the last few decades and significantly contributed to socio-economic development. Estimates of total aquaculture production in Thailand have gradually grown from around 0.6 to 0.9 million tons over the last twenty years. Farmed shrimp is the main animal aquatic product, accounting for an estimated 40% of total yields of aquaculture production, closely followed by fish (38%) and mollusk (22%). Estimates over the past decades indicate that around 199470 ha of land is used for aquaculture farming. Out of the total area, 61% is used for freshwater farms, and 39% is used for coastal farms. However, this industry has contributed to environmental degradation, such as habitat destruction, water pollution, and ecological effects. Effective management strategies are urgently needed to minimize the environmental impacts of aquaculture and to ensure it maximally contributes to planetary health. Innovative and practical solutions that rely on diverse technology inputs and smart market-based management approaches that are designed for environmentally friendly aquaculture farming can be the basis for viable long-term solutions for the future

Teaching Ways and Learning Ways Revisited

In learning and teaching of languages, numerous theories have been put forward. These theories, normally influenced by developments in the fields of linguistics and psychology, have inspired several approaches to the teaching of second and foreign languages. This paper revisits English language teaching approaches, both traditional and modern, as well as learning styles and teaching styles. Such learning style models as The Myers-Briggs Type Indicator (MBTI); Kolb’s Experiential Learning Model; the Felder-Silverman Learning Styles Model are explored in-depth in this paper. Keywords: teaching approach; learning style; teaching styl