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Publisher: SciELO   (Total: 745 journals)

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Showing 601 - 746 of 746 Journals sorted alphabetically
Revista Estudos Feministas     Open Access   (SJR: 0.208, CiteScore: 0)
Revista Facultad de Ciencias Económicas: Investigación y Reflexión     Open Access  
Revista Facultad de Ingenieria - Universidad de Tarapaca     Open Access   (Followers: 1)
Revista Facultad de Ingeniería Universidad de Antioquia     Open Access   (Followers: 1, SJR: 0.172, CiteScore: 0)
Revista Facultad de Medicina de la Universidad Nacional de Colombia     Open Access   (SJR: 0.125, CiteScore: 0)
Revista Facultad Nacional de Agronomía, Medellín     Open Access   (SJR: 0.138, CiteScore: 0)
Revista Facultad Nacional de Salud Pública     Open Access  
Revista Gaúcha de Enfermagem     Open Access   (SJR: 0.225, CiteScore: 1)
Revista Geológica de América Central     Open Access  
Revista Geológica de Chile     Open Access   (Followers: 1)
Revista Gerencia y Políticas de Salud     Open Access   (SJR: 0.136, CiteScore: 0)
Revista Habanera de Ciencias Médicas     Open Access   (SJR: 0.211, CiteScore: 0)
Revista Historia y Sociedad     Open Access  
Revista IBRACON de Estruturas e Materiais     Open Access   (Followers: 1)
Revista Ingenieria de Construcción     Open Access   (Followers: 1, SJR: 0.204, CiteScore: 0)
Revista Ingenierías Universidad de Medellín     Open Access  
Revista Integra Educativa     Open Access  
Revista Interamericana de Bibliotecología     Open Access   (Followers: 7)
Revista Internacional de Contaminación Ambiental     Open Access   (SJR: 0.152, CiteScore: 0)
Revista ION     Open Access  
Revista IUS     Open Access  
Revista Katálysis     Open Access  
Revista Lasallista de Investigación     Open Access   (SJR: 0.146, CiteScore: 0)
Revista Latino-Americana de Enfermagem     Open Access   (SJR: 0.339, CiteScore: 1)
Revista Latinoamericana de Bioética     Open Access  
Revista Latinoamericana de Desarrollo Económico     Open Access  
Revista Latinoamericana de Filosofía     Open Access   (Followers: 1)
Revista Latinoamericana de Investigación en Matemática Educativa     Open Access   (SJR: 0.171, CiteScore: 0)
Revista Latinoamericana de Psicopatologia Fundamental     Open Access   (SJR: 0.201, CiteScore: 0)
Revista Medica de Chile     Open Access   (SJR: 0.259, CiteScore: 1)
Revista Médica del Hospital Nacional de Niños Dr. Carlos Sáenz Herrera     Open Access   (Followers: 1)
Revista Médica Electrónica     Open Access  
Revista Médica La Paz     Open Access  
Revista Médico-Científica : Luz y Vida     Open Access  
Revista Mexicana de Análisis de la Conducta     Open Access   (SJR: 0.405, CiteScore: 1)
Revista Mexicana de Astronomía y Astrofísica     Open Access   (Followers: 2, SJR: 0.596, CiteScore: 1)
Revista Mexicana de Biodiversidad     Open Access   (SJR: 0.421, CiteScore: 1)
Revista Mexicana de Ciencias Agrícolas     Open Access   (Followers: 1)
Revista Mexicana de Ciencias Farmaceuticas     Open Access   (Followers: 1)
Revista Mexicana de Ciencias Geológicas     Open Access   (SJR: 0.308, CiteScore: 1)
Revista Mexicana de Ciencias Pecuarias     Open Access   (Followers: 1, SJR: 0.17, CiteScore: 0)
Revista Mexicana de Economía y Finanzas     Open Access  
Revista Mexicana de Física     Open Access   (SJR: 0.203, CiteScore: 0)
Revista mexicana de física E     Open Access  
Revista Mexicana de Fitopatología     Open Access  
Revista Mexicana de Ingeniería Química     Open Access   (SJR: 0.328, CiteScore: 1)
Revista Mexicana de Investigación Educativa     Open Access   (Followers: 3, SJR: 0.291, CiteScore: 0)
Revista Mexicana de Micologí­a     Open Access  
Revista Mexicana de Sociologí­a     Open Access   (Followers: 9, SJR: 0.142, CiteScore: 0)
Revista Musical Chilena     Open Access   (SJR: 0.1, CiteScore: 0)
Revista MVZ Córdoba     Open Access   (SJR: 0.173, CiteScore: 0)
Revista Odonto Ciência     Open Access   (SJR: 0.101, CiteScore: 0)
Revista Opinión Jurídica     Open Access  
Revista Panamericana de Salud Pública     Open Access   (SJR: 0.452, CiteScore: 1)
Revista Paulista de Pediatria     Open Access   (SJR: 0.472, CiteScore: 1)
Revista Perspectivas     Open Access  
Revista Pilquen : Sección Ciencias Sociales     Open Access  
Revista Portuguesa de Cirurgia     Open Access   (Followers: 1)
Revista Portuguesa de Enfermagem de Saúde Mental     Open Access  
Revista Portuguesa de Imunoalergologia     Open Access   (Followers: 2, SJR: 0.141, CiteScore: 0)
Revista Portuguesa de Ortopedia e Traumatologia     Open Access  
Revista Portuguesa de Saúde Pública     Open Access   (SJR: 0.155, CiteScore: 0)
Revista Portuguesa e Brasileira de Gestão     Open Access  
Revista Signos     Open Access   (SJR: 0.174, CiteScore: 0)
Revista Universitaria de Geografía     Open Access  
Revista Uruguaya de Cardiologia     Open Access  
Revista Veterinaria     Open Access   (SJR: 0.105, CiteScore: 0)
RGO : Revista Gaúcha de Odontologia     Open Access   (SJR: 0.104, CiteScore: 0)
RISTI : Revista Ibérica de Sistemas e Tecnologias de Informação     Open Access   (SJR: 0.213, CiteScore: 1)
RLA : revista de linguistica teorica y aplicada     Open Access   (Followers: 1, SJR: 0.192, CiteScore: 0)
Rodriguésia     Open Access   (SJR: 0.734, CiteScore: 2)
SA Orthopaedic J.     Open Access   (Followers: 2)
Salud Colectiva     Open Access   (SJR: 0.22, CiteScore: 0)
Salud Mental     Open Access   (Followers: 1, SJR: 0.173, CiteScore: 1)
Sanidad Militar     Open Access  
São Paulo em Perspectiva     Open Access  
Sao Paulo Medical J.     Open Access   (SJR: 0.334, CiteScore: 1)
Saúde Coletiva     Open Access  
Saúde e Sociedade     Open Access   (SJR: 0.384, CiteScore: 0)
Saúde em Debate     Open Access  
Sba: Controle & Automação Sociedade Brasileira de Automatica     Open Access  
Scientia Agricola     Open Access   (SJR: 0.578, CiteScore: 2)
Scientiae Studia     Open Access  
Secuencia     Open Access   (SJR: 0.101, CiteScore: 0)
Serviço Social & Sociedade     Open Access   (Followers: 1)
Sexualidad, Salud y Sociedad (Rio de Janeiro)     Open Access   (Followers: 2)
Si Somos Americanos     Open Access  
Signos Filosóficos     Open Access   (SJR: 0.107, CiteScore: 0)
Signos Historicos     Open Access   (SJR: 0.102, CiteScore: 0)
Silva Lusitana     Open Access  
Sociedade & Natureza     Open Access  
Sociedade e Estado     Open Access   (Followers: 2, SJR: 0.127, CiteScore: 0)
Sociologia : Revista da Faculdade de Letras da Universidade do Porto     Open Access  
Sociologias     Open Access   (Followers: 2, SJR: 0.15, CiteScore: 0)
Sociológica     Open Access   (Followers: 2)
Soldagem & Inspeção     Open Access   (SJR: 0.238, CiteScore: 0)
South African Dental J.     Open Access  
South African J. of Agricultural Extension     Open Access   (Followers: 4)
South African J. of Animal Science     Open Access   (Followers: 3, SJR: 0.387, CiteScore: 1)
South African J. of Childhood Education     Open Access   (Followers: 1)
South African J. of Enology and Viticulture     Open Access   (SJR: 0.301, CiteScore: 1)
South African J. of Industrial Engineering     Open Access   (Followers: 3, SJR: 0.201, CiteScore: 1)
South African J. of Occupational Therapy     Open Access   (Followers: 40)
South African J. of Surgery     Open Access   (Followers: 1, SJR: 0.162, CiteScore: 0)
South African Medical J.     Open Access   (Followers: 5, SJR: 0.45, CiteScore: 1)
Studia Historiae Ecclesiasticae     Open Access   (Followers: 3)
Summa Phytopathologica     Open Access   (SJR: 0.258, CiteScore: 0)
Superficies y vacio     Open Access  
Tecnología Química     Open Access  
Tecnología y Ciencias del Agua     Open Access   (SJR: 0.153, CiteScore: 0)
Temas y Debates     Open Access  
Tempo     Open Access   (Followers: 2, SJR: 0.103, CiteScore: 0)
Tempo Social     Open Access   (Followers: 2, SJR: 0.135, CiteScore: 0)
Teología y Vida     Open Access   (Followers: 1, SJR: 0.122, CiteScore: 0)
Terapia Psicológica     Open Access   (SJR: 0.394, CiteScore: 1)
Texto & Contexto - Enfermagem     Open Access   (SJR: 0.273, CiteScore: 1)
The European J. of Psychiatry (edicion en español)     Open Access   (Followers: 1)
Theologica Xaveriana     Open Access   (SJR: 0.14, CiteScore: 0)
Tinkazos     Open Access  
Tópicos del seminario     Open Access   (Followers: 1)
Toxicodependências     Open Access  
Trabalho, Educação e Saúde     Open Access  
Trabalhos em Linguistica Aplicada     Open Access  
Trans/Form/Ação - Revista de Filosofia     Open Access   (SJR: 0.1, CiteScore: 0)
Transinformação     Open Access   (Followers: 1, SJR: 0.192, CiteScore: 0)
Trends in Psychiatry and Psychotherapy     Open Access   (Followers: 9, SJR: 0.323, CiteScore: 1)
Tydskrif vir Geesteswetenskappe     Open Access   (SJR: 0.193, CiteScore: 0)
Tydskrif vir Letterkunde     Open Access   (SJR: 0.235, CiteScore: 0)
Ultima Década     Open Access  
Universidad y Ciencia     Open Access   (Followers: 1)
Universitas Medica     Open Access   (Followers: 1)
Universitas Philosophica     Open Access  
Universitas Scientiarum     Open Access   (SJR: 0.192, CiteScore: 1)
Universum : Revista de Humanidades y Ciencias Sociales     Open Access   (Followers: 1, SJR: 0.155, CiteScore: 0)
Vaccimonitor     Open Access   (Followers: 1, SJR: 0.177, CiteScore: 0)
Varia Historia     Open Access   (SJR: 0.152, CiteScore: 0)
Veritas : Revista de Filosofí­a y Teología     Open Access   (Followers: 1, SJR: 0.101, CiteScore: 0)
Veterinaria (Montevideo)     Open Access  
Veterinaria México     Open Access  
Vibrant : Virtual Brazilian Anthropology     Open Access  
Visión de futuro     Open Access  
Vniversitas     Open Access   (SJR: 0.16, CiteScore: 0)
Water SA     Open Access   (Followers: 2, SJR: 0.361, CiteScore: 1)
West Indian Medical J.     Open Access   (Followers: 1, SJR: 0.174, CiteScore: 0)
Yesterday and Today     Open Access   (Followers: 1)
Zoologia (Curitiba)     Open Access  

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Journal Cover
Water SA
Journal Prestige (SJR): 0.361
Citation Impact (citeScore): 1
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0378-4738 - ISSN (Online) 1816-7950
Published by SciELO Homepage  [745 journals]
  • Policy implementation considerations for basic services: A South African
           urban sanitation case

    • Abstract: The Republic of South Africa formulated numerous progressive laws, regulations and strategies from 1994 to 2008 to support the provision of free basic sanitation access to the poor by 2014. The State has yet to achieve this objective in urban areas - ostensibly due to the poor municipal execution of national policy. This paper challenges this viewpoint, as it ignores policy weaknesses and overlooks the influence of non-municipal actors in service delivery. An assessment of national policy and implementation in South Africa's second largest city (Cape Town) indicated that irreconcilable differences between municipal officials, residents and advocates' interpretations of broadly-framed national policy, as well as policy gaps specific to servicing informal settlements and providing shared sanitation, contributed to the municipality's failure to achieve policy objectives. The actors' differences and policy shortcomings necessitated municipal policy reformulation according to the 'lived' and 'practical' realities of servicing informal settlements. The findings suggest a disproportionate focus on turning national policy into practice - for this viewpoint misses how local actors' perspectives and current practices can shape policy. Understanding, accepting and addressing the interplay between policymaking and implementation can contribute to more constructive means of effectively delivering sanitation in South Africa.
       
  • Evaluation of the responses of institutions and actors to the 2015/2016 El
           Niño drought in the Komati catchment in Southern Africa: lessons to
           support future drought management

    • Abstract: Future climate projections for Southern Africa indicate an increase in the severity of droughts. Drought preparedness and management are important in such regions to minimise impacts on people and the environment. The aim of this study was to explore the responses of different institutions and actors to the 2015/2016 drought in the Komati catchment, and, consequently, what these experiences imply for drought management in the future. This was done through in-depth interviews with 30 key actors in the study area, including farmers, engineers, water managers and weather services personnel. Additionally, we examined data on precipitation, streamflows, reservoir levels, publications and communications in media, and minutes of the Komati Joint Operation Forum (KJOF) meetings. The results indicate that, whereas scientific tools for water resources management and drought forecasting exist in the catchment, the information generated using the tools was not sufficiently utilised in water (re) allocation decision making. This can be explained by the indifference of many stakeholders to early warning information, and by the preference of stakeholders to secure farm water supplies to minimize socio-economic losses in the short term. This resulted in late implementation of drought measures, when the drought had already started. Most of the measures implemented (i.e. water rationing and intensified monitoring) only helped partially in the crisis situation and did not tackle the root causes of vulnerability of the water users, especially for farmers. From the 2015/2016 drought we learnt that pro-active drought management could be supported through developing a drought management plan that is endorsed by all actors. More efforts are needed to improve how weather forecast information is packaged, communicated, deliberated and used by institutions (e.g. KJOF) and end-users (e.g. farmers). Moreover, this case study demonstrates that learning from past drought events is useful for improving evidence-based tools, policies and practices for drought management.
       
  • Drivers and barriers to sustainable fisheries in two peri-urban
           impoundments in Zimbabwe

    • Abstract: Fisheries sustainability is categorised through four conceptual pillars: ecological, economic, and social, including cultural and institutional. Much work on fisheries sustainability has been done in marine fisheries relative to inland fisheries. Two inland peri-urban impoundments, Chivero and Manyame in Zimbabwe, support numerous small-scale fisheries; however, environmental and socioeconomic variables threaten the sustainability of the fisheries. This study aimed to identify and contextualise drivers and barriers to sustainability of small-scale fisheries in these two peri-urban impoundments. We applied three frameworks, Fishery Performance Indicators, Community-Based Fishery Indicators and FAO Small-Scale Fisheries Indicators, to identify and contextualise the drivers and barriers. Quantitative and qualitative methods were used to collect data from fishers in the two impoundments. A structured questionnaire was administered to 115 fishers in 23 fishing companies operating in the two lakes. Fisheries income and revenue as well as food security are key drivers. Lack of post-harvest equipment, volatile fish markets, water quality and quantity deterioration and fish stock decreases are key barriers to sustainability of fisheries in the two impoundments. There are subtle differences in the extent and impact of the drivers and barriers of fisheries sustainability in the two lakes. The differences relate to the uniqueness of the aquatic habitats, social constructs and fisheries operational frameworks in each lake. This suggests a need to assess fisheries sustainability using an integrated bottom-up approach starting from individual fisheries < community fisheries < global/generic fisheries.
       
  • Impacts of alien plant invasions on water resources and yields from the
           Western Cape Water Supply System (WCWSS)

    • Abstract: A key motivation for managing invasive alien plant (IAP) species is their impacts on streamflows, which, for the wetter half of South Africa, are about 970 m³∙ha−¹∙a−¹ or 1 444 mill. m³∙a−¹ (2.9% of naturalised mean annual runoff), comparable to forest plantations. However, the implications of these reductions for the reliability of yields from large water supply systems are less well known. The impacts on yields from the WCWSS were modelled under three invasion scenarios: 'Baseline' invasions; increased invasions by 2045 under 'No management'; and under 'Effective control' (i.e. minimal invasions). Monthly streamflow reductions (SFRs) by invasions were simulated using the Pitman rainfall−runoff catchment model, with taxon-specific mean annual and low-flow SFR factors for dryland (upland) invasions and crop factors for riparian invasions. These streamflow reduction sequences were input into the WCWSS yield model and the model was run in stochastic mode for the three scenarios. The 98% assured total system yields were predicted to be ±580 million m³∙a−¹ under 'Effective control', compared with ±542 million m³∙a−¹ under 'Baseline' invasions and ±450 mill. m³∙a−¹ in 45 years' time with 'No management'. The 'Baseline' invasions already reduce the yield by 38 mill. m³∙a−¹ (two thirds of the capacity of the Wemmershoek Dam) and, in 45 years' time with no clearing, the reductions would increase to 130 mill. m³∙a−¹ (capacity of the Berg River Dam). Therefore IAP-related SFRs can have significant impacts on the yields of large, complex water supply systems. A key reason for this substantial impact on yields is that all the catchments in the WCWSS are invaded, and the invasions are increasing. Invasions also will cost more to clear in the future. So, the best option for all the water-users in the WCWSS is a combined effort to clear the catchments and protect their least expensive source of water.
       
  • Ecological responses of periphyton dry mass and epilithic diatom community
           structure for different atrazine and temperature scenarios

    • Abstract: Climate change-induced temperature increase may influence the ecotoxicity of agricultural herbicides such as atrazine and consequently negatively impact aquatic biota. The objective of this study was to assess the effects of increased temperature on the ecotoxicity of atrazine to diatom community structure and stream periphyton load using laboratory microcosm experiments. A natural periphyton community from the Mukwadzi River, Zimbabwe, was inoculated into nine experimental systems containing clean glass substrates for periphyton colonisation. Communities were exposed to 0 µg∙L-1 (control), 15 µg∙L-1 and 200 µg∙L-1 atrazine concentrations at 3 temperature levels of 26°C, 28°C and 30°C. Periphyton dry weight and community taxonomic composition were analysed on samples collected after 1, 2 and 3 weeks of colonisation. A linear mixed-effects model was used to analyse the main and interactive effects of atrazine and temperature on dry mass, species diversity, evenness and richness. Temperature and atrazine had significant additive effects on species diversity, richness and dry mass. As temperature increased, diatom species composition shifted from heat-sensitive species such as Achnanthidium affine to heat-tolerant species such as Achnanthidium exiguum and Epithemia adnata. Increasing temperature in aquatic environments contaminated with atrazine results in sensitive and temperature-intolerant diatoms being eliminated from periphyton communities. Climate change will exacerbate effects of atrazine on periphyton dry mass and diatom community structure.
       
  • Evaluation of persistent organochlorine pesticides and polychlorinated
           biphenyls in Umgeni River bank soil, KwaZulu-Natal, South Africa

    • Abstract: This study investigated the presence and distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in soil collected along the banks of the Umgeni River, one of the largest rivers in the province of KwaZulu-Natal, South Africa. The analysis was performed using gas chromatography-mass spectrometry (GC-MS). The results showed that the levels of OCPs ranged from 3.58±0.09 ng/g for hexachlorobenzene (HCB) to 82.65±2.82 ng/g for HCH, with an individual mean concentration of 24.33±2.00 ng/g dry weight (dw). The levels of PCBs ranged from 10.46 ng/g for PCB105 to 89.46 ng/g for PCB180, with an average PCB value of 25.47±1.26 ng/g, dw. The highest levels of OCPs and PCBs were found at Northern Wastewater Treatment Plant (mean OCP: 32.39±3.97 ng/g and PCB: 67.87±1.67 ng/g). The two most abundant contaminants in the river were endrin and PCB180.
       
  • Laboratory method design for investigating the phytoremediation of
           polluted water

    • Abstract: The performance of plants to remove, remediate or immobilise environmental contaminants in a growth matrix through natural biological, chemical or physical activities was studied in a laboratory phytoremediation system. This study aimed to develop a novel phytoremediation system capable of investigating the remediation of agricultural pollutants by individual and multiple plant species. The designed system analysed community phytoremediation by uniquely implementing multiple plant species within the same growth silo, with indigenous and alien assemblages compared to establish community performance, highlighting the importance of biodiversity in plant assemblages. The constructed system successfully analysed the phytoremediatory capabilities of plant species within the critically endangered Renosterveld vegetation type, with unvegetated soil controls included to illustrate the pollutant removal efficiency of plants only. Growth silos were constructed from PVC piping and irrigated with drippers from a submersible pump. Eighteen different plant species were included in the experiment, i.e., 14 indigenous species, 3 invasive alien plant (IAP) species, and Palmiet. Five agricultural pollutant parameters were analysed, i.e., for fertilizers NH3-N, NO3−-N and PO4³−-P and for herbicide contamination using two glyphosate concentrations. The growth silos and unvegetated soil control were irrigated using a pollutant-municipal water solution at 3-day intervals. The multiple plants per silo design approach seeks to contribute to the limited literature pertaining heterogeneity importance, by comparing the pollutant removal performance of plant assemblages. Community comparison further investigated the biofilter implementation potential of indigenous South African plants as an alternative to their more invasive alien counterparts, adding to the knowledge base of plant-based phytoremediation by indigenous South African plant species. The laboratory phytoremediation system successfully measured the agricultural pollutant removal performance of individual plants and vegetative communities, with soil remediation influence acknowledged. The proposed system is a simple and inexpensive method for obtaining the plant-based biofiltration efficiency of individual and multiple plant species.
       
  • Transport of pore-water oxygen with/without aeration in subsurface
           wastewater infiltration system

    • Abstract: In this study, three subsurface wastewater infiltration systems (SWISs) at different aeration were set up to study the transport of pore-water oxygen and quantify the amount of trapped gas. Bromide and dissolved oxygen were introduced into SWISs as partitioning tracer and non-partitioning tracer, respectively. A model named CXTFIT based on the convection diffusion equation was used to describe the shape of breakthrough curves for bromide and dissolved air in column experiments. In CXTFIT code, the parameter β obtained from the bromide test ranging from 0.2940 to 0.7600 indicates that the physical non-equilibrium model was relatively suitable for dissolved air transport. Retardation factors obtained by CXTFIT code indicate 2-20% porosity filled with gas. Tracing the transport of air and determining the percentage of porosity filled with trapped gas has lain a foundation for further study on gas clogging in SWISs.
       
  • Finding optimal algal/bacterial inoculation ratio to improve algal biomass
           growth with wastewater as nutrient source

    • Abstract: Algal growth, nutrient removal and settling efficiency were quantified while inoculating sequencing batch reactors with a mixture of microalgae and bacteria (activated sludge). Three algae/bacteria inoculation ratios (5:1, 1:1 and 1:5) as well as pure algal biomass (control) were assessed. Algal biomass production increased with the addition of activated sludge. However, the addition of too much activated sludge can cause disturbance to the Al-Bac biomass growth and algal bacterial processes. All reactors including the control with only algae showed similar settling and nutrient removal efficiencies. Good settling was observed in all reactors with only 5% of total biomass found in supernatant after 1 h of settling. Removal efficiencies of COD, TN and PO4-P in all reactors were 79-82%, 61-65% and 15-37%, respectively, with the lowest phosphorus removal efficiency belonging to 1:5 algae/activated sludge ratio. These results may be due to both long hydraulic (7 days) and solids retention times (up to 30 days). Finally, Al-Bac biomass with 1:1 inoculation ratio showed the best enhancement in terms of biomass growth and algal activities.
       
  • Evaluation of acidogenic sludge from anaerobic reactors running at low
           solids retention times to reduce sludge generation and enhance biogas
           production

    • Abstract: Sludges generated in the biological processing of sewage are complex mixtures, the constituents of which pose risks to public health and the environment. Anaerobic digestion is considered the most sustainable option for treating sludge because it offers the possibility of generating biogas. The aim of this study was to compare the quantities, properties, biodegradabilities and biochemical methane potentials (BMP) of primary sludge (PS) generated by a primary decanter with acidogenic sludges produced by upflow anaerobic (UA) reactors operating at solids retention times (SRTs) of 2, 4, 6 and 8 days (Samples S2, S4, S6 and S8, respectively). Sludges from both pre-treatments were submitted to alkaline solubilization in order to determine the efficiency of the process in disrupting extracellular complexes. Based on the levels of total solids (TS) present, the primary decanter was found to generate higher quantities of excess sludge (yield of 3.1 gTS∙d−1) than UA reactors operating at low SRTs (yields in the range 1.69 to 0.64 gTS∙d−1). The concentrations of dissolved materials in PS and Samples S2 and S8 were considerably higher after alkaline solubilization, with respective increases of 8, 14 and 28-fold in dissolved organic carbon, 12, 20 and 40-fold in chemical oxygen demand, 25, 31 and 59-fold in proteins, and 17, 21 and 63-fold in carbohydrates. In addition, the BMP value for S8 was some 13% higher than that recorded for PS while the kinetic constant for gas production by S8 was 1.8-fold greater than that of PS. It is concluded that a pre-treatment combining anaerobic digestion at low SRT and alkaline solubilisation would lead to improved performance in subsequent stages of anaerobic digestion and, consequently, increased efficiency in biogas production.
       
  • Quality of water recovered by treating acid mine drainage using
           pervious concrete adsorbent

    • Abstract: In this paper, a batch experiment was conducted to evaluate the water quality obtained from using pervious concrete (PERVC) technology to treat acid mine drainage (AMD). The study proposes an innovative application of PERVC as a permeable reactive barrier liner in evaporation ponds. The effectiveness of PERVC adsorbent in removing heavy metals was compared with that of zero-valent iron (ZVI) of particle size 1.0 to 1.8 mm. The AMD used in the study was obtained from abandoned gold and coal mines. PERVC mixtures consisted of granite aggregate and ordinary Portland cement CEM I 52.5R (CEM I) or CEM I containing Class F 30% fly ash (30%FA) as a cement replacement material. ZVI was prepared from a mixture of silica sand and iron grit of specific sizes. PERVC and ZVI media were used to conduct batch reactor tests with AMD, for a period of 43 days at a ratio of 1 L of reactive material to 3 L of AMD. The quality of treated AMD was compared against effluent discharge standards. The contaminants Al, Fe and Zn were effectively removed by both PERVC and ZVI. Also, both adsorbents reduced Ni, Co and Cu to levels below those measured in raw AMD. However, PERVC was more effective in removing Mn and Mg while ZVI was ineffective. Although PERVC removed more heavy metals and with greater efficiency than ZVI, the PERVC-treated water showed high pH levels and exhibited elevated Cr6+ concentrations, owing to leaching from the cement and fly ash materials used in PERVC mixtures.
       
  • The investigation into the adsorption removal of ammonium by natural and
           modified zeolites: kinetics, isotherms, and thermodynamics

    • Abstract: The objectives of this study were to modify Chinese natural zeolite by NaCl and to investigate its suitability as a low-cost clay adsorbent to remove ammonium from aqueous solution. The effect of pH on ammonium removal was investigated by batch experiments. The findings indicated that pH has a significant effect on the removal of ammonium by M-Zeo and maximum adsorption occured at pH 8. Ion exchange dominated the ammonium adsorption process at neutral pH, with the order of exchange selectivity being Na+> Ca2+> K+> Mg2+. The Freundlich model provided a better description of the adsorption process than the Langmuir model. The maximum ammonium adsorption capacity was 17.83 mg/g for M-Zeo at 293K. Considering the adsorption isotherms and thermodynamic studies, the adsorption of ammonium by M-Zeo was endothermic and spontaneous chemisorption. Kinetic studies indicated that the adsorption of ammonium onto M-Zeo is well fitted by the pseudo-second-order kinetic model. Ea in the Arrhenius equation suggested the adsorption of ammonium on M-Zeo was a fast and diffusion-controlled process. The regeneration rate was 90.61% after 5 cycles. The removal of ammonium from real wastewater was carried out, and the removal efficiency was up to 99.13%. Thus, due to its cost-effectiveness and high adsorption capacity, M-Zeo has potential for use in ammonium removal from aqueous solutions.
       
  • Comparison of refined and non-refined wastewater effect on wheat seed
           germination and growth under drought

    • Abstract: Wastewater has attracted special attention as a possible source of irrigation. The present study aimed to compare the effect of refined and non-refined wastewater on wheat seed germination and growth under induced drought conditions in laboratory and pot experiments. The laboratory experiment included the iso-osmotic potentials of −0.275, −0.4, and −0.47 MPa of polyethylene glycol (PEG, as a drought factor) and wastewater. In addition, the pot experiment included a wastewater factor (i.e., tap water, 100% refined wastewater, 50% refined wastewater + 50% non-refined wastewater, and 100% non-refined wastewater) and a drought factor (i.e., an irrigation interval of two and three days as normal and drought conditions, respectively). The results demonstrated that the drought related to PEG did not reduce seed germination while wastewater decreased seed germination. Further, an osmotic potential of −0.47 MPa resulted in the highest and lowest radicle length in both wastewater and PEG, respectively. The results also revealed that caulicle length and seed vigour were decreased by PEG as the osmotic potential increased while no significant difference was observed between wastewater treatments and distilled water (control). Based on the results, an irrigation interval of 3 days with 100% non-refined wastewater produced the highest chlorophyll content and 100% refined and 100% non-refined wastewater produced a larger leaf area compared to the control. Furthermore, drought with wastewater application increased specific leaf weight whereas it reduced the total biomass compared to control (i.e., tap water with an irrigation interval of 2 days), except for 100% non-refined wastewater. Therefore, wastewater application compensates for the adverse effect of drought due to nutrient addition.
       
  • Modelling maize grain yield and nitrate leaching from sludge-amended soils
           across agro-ecological zones: A case study from South Africa

    • Abstract: When applying municipal sludge according to crop N requirements, the primary aim should be optimizing sludge application rates in order to maximize crop yield and minimize environmental impacts through nitrate leaching. Nitrate leaching and subsequent groundwater contamination is potentially one of the most important factors limiting the long-term viability of sludge application to agricultural soils. This study assessed maize grain yield and potential nitrate leaching from sludge-amended soils, using the SWB-Sci model, based on crop nitrogen requirements and inorganic fertilizer. The following hypotheses were tested using the SWB-Sci model and 20 years of measured weather data for 4 of the 6 South African agro-ecological zones. Under dryland maize cropping, grain yield and nitrate leaching from sludge-amended soils compared to inorganic fertilizer: (1) will remain the same across agro-ecological zones and sites, (2) will not vary across seasons at a specific site, and (3) will not vary across soil textures. Model simulations showed that annual maize grain yield and nitrate leaching varied significantly (P> 0.05) across the four agro-ecological zones, both for sludge-amended and inorganic fertilizer amended soils. The annual maize grain yield and nitrate leaching from sludge-amended soils were 12.6 t∙ha−¹ and 32.7 kgNO3-N∙ha−¹ compared to 10.2 t∙ha−¹ and 43.2 kgNO3-N∙ha−¹ for inorganic fertilizer in the super-humid zone. Similarly, maize grain yield and nitrate leaching varied significantly across seasons and soil textures for both sludge and inorganic fertilizer amended soils. However, nitrate losses were lower from sludge-amended soils (2.3-8.2%) compared to inorganic fertilizer (11.1-26.7%) across all zones in South Africa. Therefore, sludge applied according to crop N requirements has a lower environmental impact from nitrate leaching than commercial inorganic fertilizer. Further validation of these findings is recommended, using field studies, and monitoring potential P accumulation for soils that received sludge according to crop N requirements.
       
  • Assessing the influence of DEM source on derived streamline and
           catchment boundary accuracy

    • Abstract: Accurate DEM-derived streamlines and catchment boundaries are essential for hydrological modelling. Due to the popularity of hydrological parameters derived mainly from free DEMs, it is essential to investigate the accuracy of these parameters. This study compared the spatial accuracy of streamlines and catchment boundaries derived from available digital elevation models in South Africa. Two versions of Stellenbosch University DEMs (SUDEM5 and DEMSA2), the second version of the 30 m advanced spaceborne thermal emission and reflection radiometer global digital elevation model (ASTER GDEM2), the 30 and 90 m shuttle radar topography mission (SRTM30 and SRTM90 DEM), and the 90 m Water Research Commission DEM (WRC DEM) were considered. As a reference, a 1 m GEOEYE DEM was generated from GeoEye stereo images. Catchment boundaries and streamlines were extracted from the DEMs using the Arc Hydro module. A reference catchment boundary was generated from the GEOEYE DEM and verified during field visits. Reference streamlines were digitised at a scale of 1:10 000 from the 1 m orthorectified GeoEye images. Visual inspection, as well as quantitative measures such as correctness index, mean absolute error, root mean squares error and figure of merit index were used to validate the results. The study affirmed that high resolution (
       
  • Assessment of straight and meandering furrow irrigation strategies under
           different inflow rates

    • Abstract: This paper reports the effect of straight furrow (SF) and meandering furrow (MF) irrigation strategies, as well as inflow rate, on infiltration and hydraulic parameters including advance time, recession time, and runoff hydrograph. The performance of SF and MF irrigation in terms of runoff ratio, deep percolation, and application efficiency was evaluated in 6 furrow fields at Shahid Bahonar University of Kerman, Iran. The required data were collected from the farm, consisting of free drainage furrows with length 70 m, top width 0.8 m, depth 0.25 m, and slope 0.2%. The advance and recession times were significantly longer in MF than SF irrigation. The infiltration was estimated by Lewis-Kostiakov equation. The infiltration coefficients were calculated: The values of k were higher and of a were lower in MF furrows than in SF furrows. The average runoff ratio and application efficiency for the SF irrigation events were 50.53% and 49.07%, respectively, while those of the MF irrigation events were 7.04% and 52.94%, respectively. Based on the results, the velocity of water advance in MF irrigation is decreased and, thus, the runoff, erosion losses, mass of fertilizer lost and surface water contamination were reduced. Using a lower inflow rate and appropriate irrigation time leads to better management outcomes in irrigation systems.
       
  • An evaluation of the primary South African standard and guideline for the
           provision of water for firefighting

    • Abstract: In South Africa, as is mostly the norm globally, national legislation and guidelines specify that potable water distribution networks maintain the capacity to provide specified quantities of water for firefighting. This paper addresses the question: is the South African standard and guideline pertaining to fire-flow provision appropriate for firefighting and do these ensure the most efficient balance between providing sufficient fire protection and promoting sustainable water use' In answering this question, this study: (i) reviewed national and international design standards and guidelines; and (ii) captured and analysed 10 years of billable fire incident reports representing 3 859 fire events within the City of Johannesburg. Highlights from the study include: inconsistencies in categories when comparing the SANS 10090 and The Red Book fire tables and violations (in The Red Book) of stipulated Minimum Fire Flows; over the 10 year period, 75% of fire incidents within the City of Johannesburg were extinguished using less than 6.6 kL of water - less than the capacity (6.9 kL) of the City's conventional pumping tanker during the period; 99.9% of fire incidents within the City were quenched using an average fire flow rate of less than 1 200 L/min, which is the minimum hydrant flow rate for the lowest fire risk category in SANS 10090; and peak fire occurrence did not correspond with typical peak residential water use. Recommendations are proffered in respect of the above.
       
  • Environmental life cycle assessment for potable water production - a case
           

    • Abstract: Water is becoming a scarce resource in many parts of South Africa and, therefore, numerous plans are being put in place to satisfy the increased urban demand for this resource. Two of the methods currently considered are desalination of seawater and reuse of mine-affected water based on the use of reverse osmosis (RO) membranes. Due to their high energy consumption and associated environmental impacts, these methods have been under scrutinity and, therefore, an LCA was undertaken for both methods. To allow comparison between the two, the functional unit of 1 kL of potable water was specified. Design data were collected for both the construction and operation phases of the plants while SimaPro was used as the LCA analysis software with the application of the ReCiPe Midpoint method. The results indicate that the operation phase carried a greater environmental burden than the materials required for the infrastructure. In particular, electricity production and consumption is responsible for the majority of environmental impacts that stem from the respective plants. The total energy consumption of the proposed desalination plant is 3.69 kWh/kL and 2.16 kWh/kL for the mine-water reclamation plant. This results in 4.17 kg CO2 eq/kL being emitted for the desalination plant and 2.44 kg CO2 eq/kL for the mine-affected plant. A further analysis indicated that replacing South African electricity with photovoltaic (solar) and wind power has the potential to bring significant environmental benefits. The integration of these renewable energy systems with desalination and membrane treatment of mine-affected water has been proven to reduce environmental burdens to levels associated with conventional water technologies powered by the current electricity mix.
       
  • The rate of release of Cry1Ab protein from Bt maize leaves into
           water

    • Abstract: Transgenic Bt maize plants are genetically modified to contain genes of Bacillus thuringiensis that encode for δ-endotoxins (Cry1Ab protein) that have insecticidal properties. These endotoxins target certain lepidopteran pests of maize. There are several entry routes by which Cry proteins enter the aquatic ecosystem in which aquatic organisms are exposed to these proteins. The main route is through plant debris such as leaves, stalks and postharvest detritus that are transported by means of run-off, rain and wind. While several studies have been conducted on the fate of Cry1Ab protein in terrestrial ecosystems, little is known of the release rates of Cry1Ab proteins from maize plant tissues that end up in aquatic ecosystems. In this study, leaves of Bt-maize and its isoline were submerged in containers filled with deionised or borehole water for a period of 16 days, and kept at 3 different temperatures (10±1, 21±1 and 30±1°C). Samples were collected at 1, 2, 4, 8, 16, 24, 48, 96, 192 and 384 h post submersion and analysed for Cry protein content using enzyme-linked immunosorbent assay (ELISA). The release of Cry protein from submerged maize leaves was influenced by temperature, and duration of immersion. An increase in Cry protein levels in the water was observed from the first hour onwards in both water types until the end of the experiment. The highest concentration of Cry protein was found at 30°C. This study showed that temperature and time period influence the release rate of Cry proteins from dried leaf matter into the aquatic environment.
       
  • Detection of selected agricultural pesticides in river and tap water in
           Letsitele, Lomati and Vals-Renoster catchments, South Africa

    • Abstract: This paper presents the levels of detection of selected agricultural pesticides in river and tap water in the Letsitele, Lomati and Vals-Renoster catchments, South Africa. Agriculture plays a major role in the development of communities through job creation and poverty eradication. However, exposure to agricultural pesticides can result in serious human health and environmental effects. This study, therefore, identified critical areas where specific pesticides might result in high environmental and human health risks. Three water catchment areas, namely, Letsitele, Lomati and Vals-Renoster, were identified for raw and tap water analysis. The results confirmed the presence of selected agricultural pesticides: atrazine, terbuthylazine, imidacloprid, metolachlor, simazine and alachlor. Although low concentrations of most of these pesticides were detected, pesticides such as atrazine, alachlor and simazine are known for endocrine disruption. A critical finding of this study is the detection of these pesticides in tap water (drinking water) of a primary school in the Lomati catchment. This reveals a high exposure potential for human health. It is thus recommended that further research be conducted to determine the potential health risks associated with these pesticides among vulnerable communities, through epidemiological studies.
       
 
 
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