Madagascar corals track sea surface temperature variability in the Agulhas Current core region over the past 334 years

The Agulhas Current (AC) is the strongest western boundary current in the Southern Hemisphere and is key for weather and climate patterns, both regionally and globally. Its heat transfer into both the midlatitude South Indian Ocean and South Atlantic is of global significance. A new composite coral record (Ifaty and Tulear massive Porites corals), is linked to historical AC sea surface temperature (SST) instrumental data, showing robust correlations. The composite coral SST data start in 1660 and comprise 200 years more than the AC instrumental record. Numerical modelling exhibits that this new coral derived SST record is representative for the wider core region of the AC. AC SSTs variabilities show distinct cooling through the Little Ice Age and warming during the late 18th, 19th and 20th century, with significant decadal variability superimposed. Furthermore, the AC SSTs are teleconnected with the broad southern Indian and Atlantic Oceans, showing that the AC system is pivotal for inter-ocean heat exchange south of Africa

Corals record long-term Leeuwin current variability including Ningaloo Niño/Niña since 1795

Variability of the Leeuwin current (LC) off Western Australia is a footprint of interannual and decadal climate variations in the tropical Indo-Pacific. La Niña events often result in a strengthened LC, high coastal sea levels and unusually warm sea surface temperatures (SSTs), termed Ningaloo Niño. The rarity of such extreme events and the response of the southeastern Indian Ocean to regional and remote climate forcing are poorly understood owing to the lack of long-term records. Here we use well-replicated coral SST records from within the path of the LC, together with a reconstruction of the El Niño-Southern Oscillation to hindcast historical SST and LC strength from 1795 to 2010. We show that interannual and decadal variations in SST and LC strength characterized the past 215 years and that the most extreme sea level and SST anomalies occurred post 1980. These recent events were unprecedented in severity and are likely aided by accelerated global ocean warming and sea-level rise. © 2014 Macmillan Publishers Limited

Arsenic removal by electrocoagulation process: Recent trends and removal mechanism

caused by the regular consumption of arsenic contaminated water, even at a lesser contaminated level. The number of arsenicosis patients is increasing day-by-day. Decontamination of arsenic from the water medium is the only one way to regulate this and the arsenic removal can be fulfilled by water treatment methods based on separation techniques. Electrocoagulation (EC) process is a promising technology for the effective removal of arsenic from aqueous solution. The present review article analyzes the performance of the EC process for arsenic removal. Electrocoagulation using various sacrificial metal anodes such as aluminium, iron, magnesium, etc. is found to be very effective for arsenic decontamination. The performances of each anode are described in detail. A special focus has been made on the mechanism behind the arsenite and arsenate removal by EC process. Main trends in the disposal methods of sludge containing arsenic are also included. Comparison of arsenic decontamination efficiencies of chemical coagulation and EC is also reported

Stabilized landfill leachate treatment using heterogeneous Fenton and electro-Fenton processes

In the present study, stabilized landfill leachate treatment by heterogeneous Fenton and electro-Fenton (EF) was carried out. Iron-manganese binary oxide loaded zeolite (IMZ) was used as a catalyst for generating hydroxyl radicals in the acidic medium. Heterogeneous Fenton process was capable of removing 88.6% COD from landfill leachate at the optimal conditions, while 87.5% COD removal was observed at optimal EF treatment conditions. Biodegradability of landfill leachate was increased significantly from 0.03 to 0.52 after Fenton treatment. The prepared heterogeneous catalyst was found reusable with a reduction in COD removal rate. Even though, both the processes are efficient for leachate treatment, the low catalyst dosage requirement in case of EF process justifies that it is more feasible than Fenton process

Stabilized landfill leachate treatment using heterogeneous Fenton and electro-Fenton processes

In the present study, stabilized landfill leachate treatment by heterogeneous Fenton and electro-Fenton (EF) was carried out. Iron-manganese binary oxide loaded zeolite (IMZ) was used as a catalyst for generating hydroxyl radicals in the acidic medium. Heterogeneous Fenton process was capable of removing 88.6% COD from landfill leachate at the optimal conditions, while 87.5% COD removal was observed at optimal EF treatment conditions. Biodegradability of landfill leachate was increased significantly from 0.03 to 0.52 after Fenton treatment. The prepared heterogeneous catalyst was found reusable with a reduction in COD removal rate. Even though, both the processes are efficient for leachate treatment, the low catalyst dosage requirement in case of EF process justifies that it is more feasible than Fenton process

Continuous treatability of oily wastewater from locomotive wash facilities by electrocoagulation

The present work focuses on the feasibility of electrocoagulation (EC) process for the treatment of oil and grease wastewater generated from locomotive wash facilities. Experimental investigations have shown the influence of various factors affecting EC using continuous reactor. The effect of various operating parameters, like reaction time, electrode spacing, and applied voltage, was investigated and optimized using Box-Behnken design method. The optimized value of applied voltage and electrode spacing were found to be 28 V and 3 cm, and Chemical Oxygen Demand removal efficiency obtained was 91.9%. As a result, EC process can be an alternative method for the treatment of oily wastewater

Removal characteristics of basic dyes from aqueous solution by fly ash in single and tertiary systems

267-272<span style="font-size:9.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"ms="" mincho";color:black;mso-ansi-language:="" en-gb;mso-fareast-language:ja;mso-bidi-language:hi"="" lang="EN-GB">The use of fly ash as a low cost adsorbent for the removal of three basic dyes from their single and tertiary aqueous solution has been investigated. Batch adsorption experiments were conducted to determine the effect of contact time and adsorbent dosage on adsorption of dyes from aqueous solution. The adsorption isotherm results indicated that the Freundlich adsorption isotherm fitted the data better than the Langmuir adsorption isotherm. <span style="font-size: 9.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-gb;mso-fareast-language:ja;mso-bidi-language:="" hi"="" lang="EN-GB">The adsorption capacity of fly ash decreases in tertiary system as compared to single system indicates the competitive sorption behaviour of fly ash. Kinetic parameters of adsorption such as the pseudo first order constant and pseudo second order constant were determined. The results of the study demonstrated that the fly ash could be used as an effective low cost adsorbent for the removal of basic dyes from aqueous solution.</span

Performance of Natural Coagulant Extracted from Plantago ovata Seed for the Treatment of Turbid Water

Present study investigates the coagulation ability of Plantago ovata (P. ovata) seed extracts for turbidity removal. The active coagulant agents were successfully extracted from P. ovata seeds using different solvents such as distilled water (PO-DW), tap water (PO-TW), NaCl (PO-NaCl), and ammonium acetate (PO-AA). Experiments were conducted in batch mode for initial turbidity such as 500 NTU (high), 150 NTU (medium), and 50 NTU (low). Results demonstrated that P. ovata extracts are less efficient in low turbidities, while PO-NaCl was found to provide high coagulation activity in all initial turbidity concentrations compared to other extracts. PO-NaCl was able to remove 98.2, 94.9, and 80.2% of turbidity from water having in initial turbidities of 500, 150, and 50 NTU, respectively. Coagulation activity of the extract was the best when the extraction was performed for 50 min at room temperature. Jar test procedure with the coagulation time of 1 min and flocculation time of 30 min was optimized, irrespective of the initial turbidity. The optimum settling time for 500, 150, and 50 NTU water samples were 20, 30, and 90 min, respectively. PO-NaCl was used in different pH turbid solutions and it was found to be working very efficiently in alkaline conditions. The coagulation efficiency of the coagulant stored in refrigerator was higher than that stored at room temperature. Thus, the natural coagulants extracted from P. ovata seeds revealed to be effective for turbidity removal

Combined Electro-Fenton and Biological Processes for the Treatment of Industrial Textile Effluent: Mineralization and Toxicity Analysis

The longer time required for complete mineralization in the electro-Fenton (EF) process can be rectified by combining the EF process with a biological method. This paper analyzes textile wastewater treatment by integrating EF and biological processes. The removal of color, chemical oxygen demand (COD), and total organic carbon (TOC) by the EF process was 63, 48, and 29% respectively. Further treatment of this wastewater by a biological process resulted in removal of 85% of color, 86% of COD, and 56% of TOC. In addition, better mineralization of dyes requires integration of aerobic and microaerophilic conditions. The phytotoxicity and microbial toxicity analysis of the treated wastewater shows that there is a significant reduction of toxicity compared with the raw wastewater. Therefore it is recommended that the combined EF and biological degradation processes be applied in the treatment of textile wastewater for removing color, COD, and TOC effectively

Review of zero-valent aluminium based water and wastewater treatment methods

Zero-valent metals (ZVM) are widely used to remove heavy metals, contaminants, toxicity, etc. from water and wastewater. Zero-valent aluminium (ZVAl) has large surface area and high surface reactivity. It has enormous flexibility for the in-situ application. ZVAl can be applied as either a single or a bimetallic system as well as advanced oxidation processes (AOPs). It is observed that ZVAl is capable of generating hydroxyl and sulfate radicals in water medium, which remove non-biodegradable pollutants from aqueous solution. ZVAl-based processes can remove non-biodegradable organic contaminants from water medium within a short duration. ZVAl is also used as a reducing agent. It is efficient to reduce toxic hexavalent chromium to less toxic trivalent chromium. ZVAl, in various combinations in bimetallic system (Fe/Al, Pd/Al, Cu/Al), is able to remove various contaminants from aqueous medium. Overall, it can be concluded that ZVAl-based methods for water and wastewater treatment are promising environmental technologies