Effect of Activated Sludge Preservation on Its Adsorption Capacity in Treatment of Wastewater

Adsorption by activated sludge which plays a significant role in substrate removal has received a lot of recognition. A number of studies have been conducted into understanding this mechanism. However, the impact of activated sludge preservation on the adsorption capacity test results has not been documented. Live activated sludge is usually preserved after sampling to maintain the original sludge characteristics in order not to alter its adsorption capacity. Preservation of the sludge is relevant when the sludge has to be transported over long distances before adsorption experiments can be conducted. This paper seeks to present the effects of preservation of activated sludge on its adsorption capacity. The preservation methods considered were pre-aeration and cold-storage of the sludge. Sludge samples were pre-aerated for periods of 4 and 24 hours at room temperature and some were stored at 4?C for 6 hours. Adsorption batch experiments were then carried out on both fresh and preserved activated sludge samples. Glucose was used as an external substrate in these experiments. The results revealed a difference between the adsorption capacity of the fresh and preserved sludge samples. Sludge pre-aeration increased the adsorption capacity of the sludge. There was however, no significant difference in the adsorption capacities for 4h and 24h pre-aerated sludge samples. Adsorption capacity of the 6h cold-stored activated sludge was poor compared to that of the fresh sludge. Keywords: Activated sludge, Activated sludge preservation, Adsorption capacity, Glucos

Treatment potential of Typha latifolia in removal of heavy metals from wastewater using constructed wetlands

The objective of the study was to evaluate the phytoremediation potential of the aquatic macrophyte Typha latifolia for removal of cadmium, chromium and lead from synthetic wastewaters in constructed wetlands (CW). Four laboratory scale CW units were set up, each containing granite and soil. Typha latifolia was planted in the 1st unit then intercropped with Vetiveria zizanioides, Phragmites australis and Cyperus latifolius in the 2nd, 3rd and 4th unit respectively. The units were treated to wastewaters of different metal concentrations and metal combinations. Wastewater was sampled at different retention periods. Results showed substantial reduction in metal concentrations. Metals were removed in the order Cr>Cd>Pb with maximum removal efficiencies being 96.36±0.52%, 95.70±1.26% and 80.59±3.58% for Cd, Cr and Pb respectively in the typha only units. The percentage removal of the metals increased with increase in retention time. This study recommends application of Typha latifolia in treatment of industrial and mine wastewater

Seasonal behaviour and spatial fluctuations of groundwater levels in long-term irrigated agriculture : the case of Wonji Shoa Sugar Estate (Ethiopia)

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Hydrochemical characterization of various surface water and groundwater resources available in Matahara areas, Fantalle Woreda of Oromiya region

Study region: The Matahara region is located in the East Showa zone of Oromiya regional state (Ethiopia). Matahra Sugar Estate and Lake Basaka (highly saline, alkaline and sodic lake) are situated within the flat plains of Matahara region. The area is vulnerable to the occurrences of various tectonic and volcanic activities due to its location in the upper most part of the Main Ethiopian Rift Valley region. Study focus: In this study, the hydrochemical properties of different surface water and groundwater bodies available at Matahara region have been characterized for quality compositions. Water samples were collected from different water sources and analyzed for important major quality parameters following standard test procedures. Other chemical indices were derived from the measured quality parameters. The potential sources of minerals were suggested for each of the considered water sources based on their quality characteristics. New hydrological insights for the region: Overall, the study result elucidates that the chemical composition of different water bodies are due to natural processes and/or anthropogenic activities within the region. The local anthropogenic processes could be discharges from factory, domestic sewage and farming activities. Some of the water types are found to have relatively higher concentration of dissolved constituents. Irrigation waters have almost equal chemical compositions, indicating their hydrochemical sources are almost the same. Most of the concentrations are relatively high in Lake Basaka, groundwater and hot springs. It is easy to imagine the potential damaging effects of such quality waters on crop production, soil properties and environment of the region. Keywords: Chemical composition, Chemical indices, Lake Basaka, Matahara, Natural processe

Status of Groundwater Table Depth Under Long-Term Irrigation in Wonji Plain: Concerns for Sustainability of Wonji-Shoa Sugar Estate, Upper Awash Valley, Ethiopia

The present study attempted to highlight the concerns of shallow groundwater table depth (GWTD) to the sustainability of Wonji-Shoa Sugar Estate (WSSE), Upper Awash Valley of Ethiopia. The recent magnitude and fluctuation of GWTD is mapped in ArcView GIS (using universal kriging technique) from the monthly GWTD monitoring data (2007-2009) using piezometer tubes. The study result clearly showed that the GWTD at WSSE was extremely shallow, showed great spatio-seasonal variability and rising trend; thus, threatening the sustainability of WSSE significantly. About 90% of the plantation fields have GWTD above the critical depth of 1.5 m below the soil surface and, hence, critically waterlogged. As a result, the estate is recently achieving only 55% of the production potential realized in the 1960s. Past trends indicate that the GW has the potential to inundate Wonji plain and is anticipated to devastate production during the next 10-15 years. Therefore, in order to sustain production system in the region, there is an urgent need to identify the possible causes of waterlogging and investigate the feasible remedial measures to combat its problems. The spatial mapping of GWTD with identified problematic areas, indicated in the current study, is believed to provide a tool for water management and, hence, crucial for the decision making and actions taking processes

On the Development of State-of-the-Art Computational Decision Support Systems for Efficient Water Quality Management: Prospects and Opportunities in a Climate Changing World

The concept of water quality has often generally revolved around the all-round safety of water for human consumption. The quality of much of the 3% of the earth’s humanly consumable water classed as freshwater is under threat of climate change, rising population numbers, indiscriminate land usage, detrimental agricultural practices and contamination from poor waste management. The need for optimal water quality enhancement has become more germane to sustainable socio-economic development. This paper examines the evolution of efforts made by the scientific community over the years to ensure water quality can be characterized and properly managed to ensure the global ever-growing demand for clean water for human consumption is continually met. The development of state-of-the-art computational decision support systems (DSS) should play a vital role. However, efforts in this regard are currently bedevilled by major challenges such as quantifying, measuring, processing and controlling the numerous metrics of water quality, as well as their adaptation and integration into a fully developed universal water quality model. In addressing these challenges, a shift towards simpler modelling approaches and the integration of uni-purpose models which can be cascaded into decision-making systems is being popularly proposed. However, with technological advancements already stimulating a water quality management revolution, there is a shift in paradigm to more universal modelling attempts with great optimism towards overcoming the challenges of developing universal water quality models and DSS. The prospects and opportunities of a water quality management renaissance offered by radical scientific innovations look promising, as the world races with time to provide support systems that can help deal better with the dynamics of sustainable water supply in increasingly contaminable environments and progressively unpredictable climates

Spark Plasma Sintering (SPS) of Multi-Principal Element Alloys of Copper-Niobium-Titanium-Di-Boride-Graphite, Investigation of Microstructures, and Properties

A near-equiatomic multi-principal element alloy of Cu40Nb30(TiB2)20C10 with both nano-particle size (14 nm) and micron-particle sizes (−44 µm) of Nb was designed and made via the spark plasma sintering technique at two different sintered temperatures of 650 °C and 700 °C with other SPS parameters being constant. The sintering mode, microstructures, microhardness, density, relative density, wear behavior, and corrosion properties of the alloys were investigated and compared to ascertain the best for aerospace applications. The SPS technique was applied to produce the tested samples in this study. The results showed that the alloys with nano-particles of Nb sintered faster, with the lowest wear rate, and their microstructure shows a dendritic configuration with the existence of graphite-rich and niobium-rich nano-segregations in the inter-dendritic areas with the lowest coefficient of friction, Cu-NbTiB2C with nano-particles of Nb sintered at 650 °C recorded the highest microhardness value (786.03 HV0.2), and CuNbTiB2C with micro-particles of Nb sintered at 700 °C exhibited the best anti-corrosion characteristics in a sulphuric acid environment. The results obtained in this study correspond to the requirements for high-performance engineering materials, which will make the novel materials relevant in the aerospace industry

Spark Plasma Sintering of Copper-Niobium-Graphite Composites, and the Investigations of Their Microstructure and Properties

The microstructures and properties of ternary copper-niobium-graphite (Cu-Nb(nano)10-C4, and Cu-Nb(micron)10-C4) composites produced via spark plasma sintering (SPS) technique have been investigated for their potential use as electrical connection materials at high-temperature application. Nowadays, there is much activity in the development of such material all over the world. This study was aimed to compare the effect of adding the nano and micron particles sizes of Nb powders in the microstructures and properties of Cu-Nb-C composites sintered at 700 and 650 °C temperatures. The investigated materials have been produced via the SPS method. The microstructures were observed by electron microscopy technique, the wear test was observed by Anton-Paar TRB3 tribometer, thermal diffusivity was observed by LFA427 NETzschlaser flash device within the temperature of 100–900 °C, and the corrosion test was performed by potentiodynamic polarization. The discoveries have been presented in the manuscript and were discussed with reference to the microstructure development, the composite with nanoparticles sintered at 650 °C displayed closed thermal stabilities as temperature increased, and it recorded a low coefficient of friction and suitable corrosion resistance, which correspond to requirements for electrical contacting materials. The SPS method of production of the composites caused initial microstructure refinement and improved the properties of the composites