Indirect Discharge Research Articles

Integrated assessment of the heavy metal pollution status and potential ecological risk in the Lagos Lagoon, South West, Nigeria

ABSTRACTThis study was carried out to assess the heavy metal pollution status and potential ecological risk in the Lagos lagoon, Nigeria. The concentrations of twelve heavy metals commonly associated with environmental pollution were determined in the sediments of the lagoon by Atomic Absorption Spectrophotometry (AAS) and the cold vapor method was employed for Mercury (Hg). Nonempirical risk indices and empirical Sediment Quality Guidelines (SQGs) were used to assess the ecological risk associated with heavy metal in the sediments. The nonempirical risk indices showed that Hg, Arsenic (As), and Cadmium (Cd) are the major contributors to the ecological risk associated with heavy metal pollution in the ecosystem. Comparison of heavy metal concentrations to the Screening Quick Reference Table (SQuiRT) showed that mean concentration of Cd (5.22 and 4.88 mg kg−1 in dry and rainy seasons, respectively) exceeds the effect range low (ERL) value (1.20 mg kg−1) in effect to biota. Industries sited around the lagoon have effluent output points in the lagoon serving as a major source of heavy metals coupled with indirect discharges from other sources. Heavy metals are nonbiodegradable, toxic and have the potential to alter ecosystem health, thus pollution sources should be effectively monitored and contained.

Enhancing nitrogen removal efficiency in a dyestuff wastewater treatment plant with the IFFAS process: the pilot-scale and full-scale studies.

The activated sludge (AS) process is widely applied in dyestuff wastewater treatment plants (WWTPs); however, the nitrogen removal efficiency is relatively low and the effluent does not meet the indirect discharge standards before being discharged into the industrial park's WWTP. Hence it is necessary to upgrade the WWTP with more advanced technologies. Moving bed biofilm processes with suspended carriers in an aerobic tank are promising methods due to enhanced nitrification and denitrification. Herein, a pilot-scale integrated free-floating biofilm and activated sludge (IFFAS) process was employed to investigate the feasibility of enhancing nitrogen removal efficiency at different hydraulic retention times (HRTs). The results showed that the effluent chemical oxygen demand (COD), ammonium nitrate (NH4+-N) and total nitrogen (TN) concentrations of the IFFAS process were significantly lower than those of the AS process, and could meet the indirect discharge standards. PCR-DGGE and FISH results indicated that more nitrifiers and denitrifiers co-existed in the IFFAS system, promoting simultaneous nitrification and denitrification. Based on the pilot results, the IFFAS process was used to upgrade the full-scale AS process, and the effluent COD, NH4+-N and TN of the IFFAS process were 91-291 mg/L, 10.6-28.7 mg/L and 18.9-48.6 mg/L, stably meeting the indirect discharge standards and demonstrating the advantages of IFFAS in dyestuff wastewater treatment.

The public health implications of pathogens in polluted aquatic ecosystems: a review

Pathogen contamination in water sources and related diseases constitute major water quality concern throughout the world. Aquatic environments near cities are usually prone to over-loading with a variety of pollutants through direct or indirect discharges. The problem is undoubtedly worse in developing world where there is higher public exposure to sources of pathogenic water contamination. Notable sources include domestic waste, industrial effluents, agricultural waste, ballast water discharge, inadequate sanitation and personal hygiene. Pathogen with its disease causing potential constitutes public health threat such as diseases breakout, risk of spread of pathogen related infections, loss of aquatic biodiversity, scarcity of public water supply and most importantly, increased rate of human mortality. Several researches in many regions of the world have reported pathogenic contamination of water to be responsible for most illnesses related to respiratory, gastrointestinal and dermatological systems, and accounts for high mortality records in many countries including Nigeria, with greater prevalence among children and pregnant women. Pathogenic bacteria, viruses, protozoan, or parasites are basically excreted in faeces or urine from infected animals, including humans. Control measure is basically by mitigation through improved sanitation/hygiene, surveillance, risk assessment study, infrastructural development, improved agricultural practices, laws, regulations, policies and public awareness/education. This review raises awareness and discusses the public health implications of pathogens in polluted aquatic ecosystems and control of public health problems associated with pathogens.Keywords: Public health, pathogens, pollution, aquatic ecosystem

Rhizofiltration of a Bordeaux mixture effluent in pilot-scale constructed wetland using Arundo donax L. coupled with potential Cu-ecocatalyst production

Rinsing tanks of crop sprayers produce significant volumes of Cu-rich Bordeaux mixture effluents (BME) that can be treated by rhizofiltration in constructed wetlands (CWs). A pilot-scale CW (6×600L) was developed to jointly rhizofiltrate such BME, produce Cu-rich root mat for ecocatalysis and provide usable shoot biomass with low Cu concentration. Three CW units were unplanted control (Ctrl) while three others were planted with Arundo donax L. (Ad) in floating racks. The rhizofiltration was carried out during 30days in the early growing season. Total Cu concentration in the BME was 4.4mgCuL−1. Copper removal peaked within the 48 first hours after Bordeaux mixture addition in the Ad and Ctrl units (i.e. 92 and 81% respectively). The BME Cu concentration met the requirement for indirect discharge of chemical industry effluents (i.e. 0.5mgCuL−1) at T48h (0.4±0.2) and T21days (0.4±0.1) for the Ad and Ctrl units, respectively. At day 30, in the Ad units, Cu concentration remaining in the water and distributed between A. donax roots, shoots was respectively 3.5, 33 and 0.5% of the initial Cu input. In the Ctrl units, Cu remaining in water was low (7%) and Cu removal (93%) could be partly explained by its immobilization in the Cu-rich biofilm (i.e. 207210±18516mgCukg−1) coating the vat wall. Foliar chlorophyll (i.e. a, b and total) and carotenoid contents decreased at day 30 but root and shoot dry weight (DW) yields increased by 23% and 47% per Ad unit, respectively. The shoot Cu concentration remained in the common range (i.e. 3–20mgCukg−1) while the root Cu concentration reached 623±140mgkg−1 allowing 786mg Cu removal by the root mat. Higher Cu concentration in BME or subsequent repetitions of treatment cycle must be tested to achieve at least 1000mgCukg−1 DW in roots (threshold value for Cu-ecocatalyst) whereas the biofilm role must deserve more attention.

Effect of Indirect Subsurface Dripper Discharge on Fruit Growth and Quality of Jujube

Effect of Indirect Subsurface Dripper Discharge on Fruit Growth and Quality of Jujube

Groundwater Flow Systems in the Sudeten Mountains: A Study of the Kamienczyk Catchment Area

This study describes various groundwater flow systems in mountainous areas where both crystalline and hard sedimentary rock formations can be found. The research was conducted in the Sudeten Mountains, in the Kamienczyk catchment area, which covers 7.85 km 2 (south-western Poland). The water circulation system and the role of tectonic zones were identified and described following an analysis of the water inflow in river systems and sources, as well as measurements of groundwater tables in wells. The modulus of spring runoff equalled 3.81 L·s -1 /km 2 , while the modulus of underground runoff amounted to 6.24-7.17 L·s -1 /km 2 . The total discharge index equalled 15.80 L·s-1/km 2 . Considering the results of the study, it can be concluded that for both the basins Kamienczyk and Kamionka groundwater runoff constituted 60-70% of all precipitation registered in the areas under study. The remaining 30-40% either evaporates or constitutes part of indirect and regional discharge. Areas drained by river sources are usually quite small, that is 0.1-0.5 km 2 . In the nine years of periodic observations, the average temperature of spring water was in the range of 7.2-7.7 °C and the variations were very low. The study results demonstrate that the depth of circulation of the water taking part in spring water discharge is between 35 to 55 m below ground level. The temperature of water in wells in Cretaceous sedimentary rocks, which ranges from 7.8 to 11 °C, is suggestive, given the mixing pattern of water inflow from the depths of 150-200 m.

Evidence of equilibrium peak runoff rates in steep tropical terrain on the island of Dominica during Tropical Storm Erika, August 27, 2015

Tropical Storm Erika was a weakly organized tropical storm when its center of circulation passed more than 150km north of the island of Dominica on August 27, 2015. Hurricane hunter flights had difficulty finding the center of circulation as the storm encountered a high shear environment. Satellite and radar observations showed gyres imbedded within the broader circulation. Radar observations from Guadeloupe show that one of these gyres formed in convergent mid-level flow triggered by orographic convection over the island of Dominica. Gauge-adjusted radar rainfall data indicated between 300 and 750mm of rainfall on Dominica, most of it over a four hour period. The result was widespread flooding, destruction of property, and loss of life. The extremity of the rainfall on steep watersheds covered with shallow soils was hypothesized to result in near-equilibrium runoff conditions where peak runoff rates equal the watershed-average peak rainfall rate minus a small constant loss rate. Rain gauge adjusted radar rainfall estimates and indirect peak discharge (IPD) measurements from 16 rivers at watershed areas ranging from 0.9 to 31.4km2 using the USGS Slope-Area method allowed testing of this hypothesis. IPD measurements were compared against the global envelope of maximum observed flood peaks versus drainage area and against simulations using the U.S. Army Corps of Engineers Gridded Surface/Subsurface Hydrologic Analysis (GSSHA) model to detect landslide-affected peak flows. Model parameter values were estimated from the literature. Reasonable agreement was found between GSSHA simulated peak flows and IPD measurements in some watersheds. Results showed that landslide dam failure affected peak flows in 5 of the 16 rivers, with peak flows significantly greater than the envelope curve values for the flood of record for like-sized watersheds on the planet. GSSHA simulated peak discharges showed that the remaining 11 peak flow values were plausible. Simulations of an additional 24 watersheds ranging in size from 2.2 to 75.4km2 provided confirmation that the IPD measurements varied from 40 to nearly 100% of the envelope curve value depending on storm-total rainfall. Results presented in this paper support the hypothesis that on average, the peak discharges scaled linearly with drainage area, and the constant of proportionality was equivalent to 134mmh−1, or a unit discharge of 37.22m3s−1km−2. The results also indicate that after the available watershed storage was filled after approximately 450–500mm of rain fell, runoff efficiencies exceeded 50–60%, and peak runoff rates were more than 80% of the peak rainfall rate minus a small constant loss rate of 20mmh−1. These findings have important implications for design of resilient infrastructure, and means that rainfall rate was the primary determinant of peak flows once the available storage was filled in the absences of landslide dam failure.

Removal of humic substances from reverse osmosis (RO) and nanofiltration (NF) concentrated leachate using continuously ozone generation-reaction treatment equipment

Concentrated leachate from membrane treatment process, which contains large amount of difficult-to-degrade humic substances, can induce potential hazards to ecological environment. In this study, the concentrated leachates from reverse osmosis (RO) and nanofiltration (NF) were treated by continuous ozone generating-reaction integrated equipment, and the removal characteristics of humic substances were analyzed using gel filtration chromatography (GFC), excitation-emission matrix fluorescence spectroscopy (EEM), XAD-8 resin fractionation, and Fourier transform infrared spectroscopy (FTIR). The results of XRD-8 fractionation and SUVA254 showed that the humic substances including humic acid (HA) and fulvic acid (FA), were effectively removed along with the breakdown of aromatic hydrocarbons and decrease in the degree of humification during the ozonation process. After 110min of reaction, HA in both concentrated leachates was completely removed. GFC analysis indicated that both concentrated leachates had much broader distribution after the degradation. The high molecular weight (MW) organic matter was transformed into low molecular weight of <10kDa. The majority of high MW organics in NF concentrate were converted to low MW molecules of 10kDa–1kDa, while those in RO concentrate were decomposed to small MW molecules of <1kDa. The results of EEM analysis implied that the degradation of HA and FA led to a significant decrease in the fluorescence intensity. Though the effluent of two concentrated leachate did not meet the maximum allowable criterion for leachate direct or indirect discharge standard in China, the composition and properties of organic matters in concentrated leachate were changed significantly after entire ozonation reaction, which would be conducive to the further biological treatment or other advanced treatment.

Environmentally friendly electrochemical recycling of indium from scrap ITO glass and PET

Indium, the key raw material used in liquid crystal displays (LCDs), light-emitting diodes (LEDs), and solar cells, is a rare metal. The demand for devices that use touch panels has grown enormously, and Indium has become a vital and indispensible material. However, the worldwide depletion of indium resources has made it necessary to recycle as much indium as possible. This is done not only for commercial purposes but also to protect the environment. Although direct electrochemical methods can be used to remove the indium-tin oxide (ITO) layer from intact discarded or defective thin-film transistor (TFT)-LCDs or from flexible polyethylene terephthalate (PET) touch panels, it is not possible to do this with broken or cracked panels, large numbers of glass fragments, or deformed PET material because the necessary electrical connections cannot be made. Therefore, in this study, an indirect electric discharge process was used. Tests were made using DC straight polarity and DC reverse polarity, and a multicylinder electrode was used to conduct carrying out of positive (or negative) electrical discharge in the electrode assembly without the need for electrical connection to the workpiece. An electric field is created by electrical discharge between the cathode and anode through the electrolyte to create an electrical field between the electrode and the ITO surfaces. There is no likelihood of the electrodes making direct contact with the ITO glass fragments, and so, the danger of short circuits is avoided. This method facilitates the smooth and highly efficient recycling of indium avoiding methods that use strong acids and other chemicals that are harmful to the environment. The higher the current used, the faster the feed rate of the workpiece can be, and removal will also be more efficient. A small gap between the electrodes (1 mm) will also speed up the removal rate. Pulsed DC current is conducive to the rapid removal of deposits of electrochemical by-product and also allows a higher feed rate. However, this raises the total electrical power input. The use of ultrasonics speeds up ITO removal as does an increase in electrolyte temperature. A small-diameter anode and a small gap between the electrodes also speed up the removal rate.

Actual mercury speciation and mercury discharges from coal-fired power plants in Inner Mongolia, Northern China

Mercury species distribution in the flue gas from three typical coal-fired power plants have been investigated using a C-5000 sampler for Ontario Hydro Method (OHM) to evaluate specified Hg emission inventories in the largest coal-production province of China, Inner Mongolia. The feed coal, bottom ash, fly ash and gypsum have also been sampled in the field. Mercury emissions are in the dominant form of Hg0 (>85%). The Hg2+ (<15%) and the Hgp (<2%) emissions are minor fractions of Hgt in the flue gas. The wet limestone flue gas desulfurization device (WLFGD) showed much higher removal efficiency for Hg2+ (87–95%) than for the other two Hg species. The input Hg/output Hg varied from 92% to 115% for the tested 3 coal-fried utility boilers during sampling time. We obtained comprehensive Hg discharge factors, including direct atmospheric Hg emission factors and indirect discharge factors of Hg associated with bottom ash, fly ash and gypsum, to the environment, designating the fates of Hg in coal. We estimated the Hg discharges from coal-fired power plants in Inner Mongolia in 2008–2014 and expanded to China. The maximum of direct Hg emissions from coal-fired power plants of Inner Mongolia was 24Mg in 2012. The Chinese coal-fired power plants emitted directly 100Mg Hg to the atmosphere every year at the nationwide air control actions. The maximum discharges of Hg associated with fly ash and gypsum of Inner Mongolia was 81Mg and 11Mg in 2012, respectively. The national Hg discharges with fly ash and gypsum every year are respectively about 300Mg and 82Mg, majority of which may be reemitted to the atmosphere by the utilization industry. Therefore, mercury emissions from coal-fired power plants are not the largest single source of Hg to the atmosphere in normal operation of the current efficient denitrification, particles control and desulfurization devices. Instead, the utilization industry of fly ash and gypsum would be emitting more Hg to the atmosphere.

New Stage-Discharge Equation for the SMBF Flume

AbstractFlumes for indirect discharge measurements are widespread and are characterized by a particular shape of the cross section area with various degrees of convergence and subsequent divergence. The flume named Samani, Magallanez, Baiamonte, Ferro (SMBF) is a simple and inexpensive instrument and its channel contraction is obtained by applying two semicylinders to the walls of a rectangular cross section. At first, in this paper a new stage-discharge equation for the SMBF flume is theoretically deduced. Then, this equation is experimentally calibrated using the laboratory measurements from the literature for different values of the contraction ratio. Finally the field measurements carried out at Sparacia experimental area (Sicily, South Italy) by a SMBF flume inserted into a horizontal flume and characterized by a contraction ratio equal to 0.5, are used for testing both the new stage-discharge relationship and the one originally proposed in the literature.

Review on groundwater as a source of nutrients to the Great Lakes and their tributaries

The role of groundwater in delivering nutrients (nitrogen and phosphorus) to the Great Lakes and their tributaries is not well understood. Consequently, this potentially important non-point source is poorly managed and often neglected. Evaluating nutrient inputs from groundwater requires knowledge of the (i) sources of groundwater nutrient contamination, (ii) physical groundwater discharge flow paths, and (iii) geochemical processes occurring along these flow paths that control the ultimate loading of nutrients to surface waters. Although groundwater quality in the Great Lakes Basin (GLB) is generally good, nutrient concentrations in aquifers can become elevated by a range of agricultural and non-agricultural activities. Nutrients can be delivered from groundwater to the Great Lakes by indirect discharge into tributaries or direct discharge into the lakes. The factors affecting these discharge pathways and their contributions to nutrient loading are distinct. The discharge of nutrients from groundwater to surface water is strongly regulated by zones of high reactivity that exist close to the sediment-water interface (i.e., riparian zone, hyporheic zone). Understanding the functioning of these zones for the landscape and hydrogeological conditions in the GLB is essential for evaluating nutrient loading to the Great Lakes and their tributaries as well as maximizing the benefits these zones can provide for water quality management. The paper concludes with a discussion of key knowledge gaps, challenges, and future research priorities that need to be addressed to evaluate and better manage this complex nutrient input to the Great Lakes and their tributaries.

ASSESSMENT, ANALYSIS AND STUDY OF ENCROACHMENTS AND CHANGE IN NATURAL WATER FLOW IN INTERIORS OF WORLD FAMOUS DAL LAKE DURING 2003 -2015.

Advancements in study and assessment of changing land use patterns using modern techniques like use of satellite data is inevitable today owing to high accuracy and ease of its accessibility to researchers. In this study, satellite images of over last ten years have been precisely used to analyze the changes in natural water flow and geographic characteristics of world famous Dal Lake in state of Jammu & Kashmir arising due uncontrolled human expansion and destruction of natural lake topography. The lake currently in advanced stages of eutrophication has been rapidly shrinking in its area at an alarming rate over last five decades. Major contributors to such changes are the direct or indirect discharge of untreated wastes from Srinagar city into water body through numerous sewer lines and uncontrolled land filling by local inhabitants in interiors of lake to meet their growing needs of urbanization and need for more agricultural land. Nutrients such as phosphorus and nitrogen derived from growth of vegetation within the lake and sewage have drastically altered water quality parameters and dramatically disrupted the Biological Oxygen Demand (BOD) of lake from years; making the water obtained from lake unfit for any kind of consumption or aquatic life. Uncontrolled pollution and wide encroachments laden with exponential increase of sewage discharges have led to severe changes in land use pattern in interiors of the lake which is the main source of destruction of natural physiognomies of lake and gradual choking up of its water sources. All this has compounded into complete breakdown of drainage mechanism of the Lake with a threat of floods in Lake Catchment unavoidable in coming time.

A Green Mixed Integer Linear Programming Model for Optimization of Byproduct Gases in Iron and Steel Industry

Byproduct gas is an important secondary energy in iron and steel industry, and its optimization is vital to cost reduction. With the development of iron and steel industry to be more eco-friendly, it is necessary to construct an integrated optimized system, taking economics, energy consumption and environment into consideration. Therefore, the environmental cost caused by pollutants discharge should be factored in total cost when optimizing byproduct gas distribution. A green mixed integer linear programming (MILP) model for the optimization of byproduct gases was established to reduce total cost, including both operation cost and environmental cost. The operation cost included penalty for gas deviation, costs of fuel and water consumption, holder booster trip penalty, and so forth; while the environmental cost consisted of penalties for both direct and indirect pollutants discharge. Case study showed that the proposed model brought an optimum solution and 2.2% of the total cost could be reduced compared with previous one.

Electrochemical behavior of Auramine O dye in aqueous solutions at lead dioxide electrode

Electrochemical behavior of Auramine O (AO) was studied by galvanostatic electrolysis at lead dioxide (Ta/PbO 2 ) anodes. The influence of operating parameters, such as current density, initial concentration of AO, temperature and initial pH value was investigated. The oxidation kinetics of the AO was followed by HPLC, UV / visible spectrophotometry and the measurement of chemical oxygen demand (COD). The experimental results showed that the electrochemical process was suitable for almost completely removing COD, due to the production of the hydroxyl radicals at the anode surface. The oxidation of AO is dependent on its initial concentration, current density, temperature and pH. COD decay follows a pseudo first-order kinetic and the process was under mass transport control. The HPLC analysis showed that the main AO oxidation products formed during electrolysis are the hydroquinone (HQ) representing the reduced form of benzoquinone (BQ) and carboxylic acids (CA). The proposed AO anodic oxidation into (BQ) is mainly based on an alternance of indirect monoelectronic discharge by the mediation of hydroxyl radicals and hydrolysis steps. The electrochemical oxidation of AO can be used as an economically adequate way for a pre-treatment of waters containing this dye followed by biological treatment.

Life Cycle Assessment of Metallic Copper Produced by the Pyrometallurgical Technology of China

With the rapid development of industry in China, China has become the largest producer of refined copper as well as the largest consumer of copper in the world. In order to provide the support for decreasing the environmental impact of the copper pyrometallurgy of China, the life cycle assessment methodology was carried out in this study to identify and analyze the typical processes’ environmental load of refined copper production from ‘cradle-to-gate’ perspective. The results showed that the most serious environmental impact of copper pyrometallurgy was abiotic depletion potential and human toxicity. The abiotic depletion potential mainly comes from the copper ore mining, for this reason, increasing the use of renewable copper is an effective means to alleviate environmental load of our country copper pyrometallurgy industry. Meanwhile, reducing the direct and indirect discharge of poisonous and harmful elements (e.g. heavy metals) from the copper ore mining stage and the copper smelting process could decrease the human health damage efficiently.

Occurrence of perfluoroalkyl and polyfluoroalkyl substances in the water environment and their removal in a water treatment process

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) are found in aquatic environments worldwide. The presence of these compounds in the water environment is still unclear, even though direct or indirect discharges of these compounds from industries to the aquatic environment are the potential routes. In this paper, PFOA and PFOS contamination of aquatic ecosystems, and their removal efficiency by different water treatment processes are reviewed. Typically, PFOS and PFOA contamination levels are higher in industrialized countries than in non-industrial countries. Coagulation, sand filtration, sedimentation, oxidation and disinfection are mostly ineffective in removing PFASs from drinking and wastewater. Granular activated carbon demonstrated the removal of PFASs and the extent of removal depends on operational conditions, such as temperature, operational life period and empty bed contact time. High-pressure membrane systems are the most suitable processes for removing the PFOS and PFOA in water sources. In the high-pressure membrane, removal of those chemicals occurs through rejection via electrostatic interaction. The extent of the reduction efficiency depends on the solution chemistry of the sample; lower pH and higher calcium ion addition in the water sample enhance the reduction efficiency in the high-pressure membrane application.

Occurrence and removal of hazardous chemicals and toxic metals in 27 industrial wastewater treatment plants in Korea

For better understanding of the occurrence and the fate of hazardous chemicals and toxic metals through industrial wastewater treatment plants (WWTPs), 27 WWTPs in Korea with each capacity over 2,000 m3/d were surveyed. The sampling campaign was conducted in July through September, 2012 three times at each WWTP for 22 hazardous chemicals and toxic metals in influents and effluents. Concentrations of benzene, mercury, 1,1-dichloroethylene, and arsenic in influents to the WWTPs were relatively high (i.e. above the effluent limits for indirect dischargers in industrial complex). Counting phase transfers for the treatment, average removal rates of volatile organic compounds and metals were over 70 and 60%, respectively. However, neither treatment processes nor conventional pollutants exhibited significant correlation with the non-conventional pollutants, possibly due to complexity of operations in full scale plants. Removal rates of selenium (30%) and 1,4-dioxane (18%) were lower than other chemicals and metals. Since selenium and 1,4-dioxane were detected at a few WWTPs, it may be more efficient to manage concerning non-conventional pollutants at each WWTPs rather than establishing a universal limits for all WWTPs.

A catchment study of sources and sinks of nutrients and sediments in south-east Australia

Summary A study of nutrient and sediment generation was carried out on a dairy farm in south eastern Australia over a period of two years. The study collected nitrogen (N), phosphorus (P) and total suspended sediment (TSS) samples from three headwater subcatchments totalling 4.4 km2 in area, which had streamflow measurement sites located at their outlets. In addition to these three sites, samples were collected from farm tracks, the discharge from a farm dam (water storage pond) and a rainfall sampler. Over 20 runoff events were monitored in addition to background flows in the catchment. The data enabled nutrient exports to be estimated from the total catchment and two of the three subcatchments. The atmospheric nutrient loads were also estimated and found to be similar to other studies in the region, and were low compared with the nutrient export. The nutrient load estimates indicated that a large proportion of the catchment Total Nitrogen (TN) and Total Phosphorus (TP) loads originated from critical source areas on the farm associated with dairy operations, and that the catchment TN and TP export rates were high compared to other studies. The sediment data also indicated that TP concentrations were closely related to TSS in samples collected from surface runoff. Catchment TN loads in baseflow were high relative to the total load, probably due to indirect effluent and direct groundwater discharges into watercourses, with high concentrations of soluble N (nitrate plus nitrite and ammonium). The farm dam was found to trap a high percentage (>60%) of the influent TP load; however, the retention of TN by the dam was seasonally varying and close to net neutral.

Removal of heavy metals by natural adsorbent: review

Water pollution by heavy metals has been recorded as a major problem in the global context. It occurs due to the direct and indirect discharge of diverse chemicals into the water bodies without sufficient treatment to reduce and diminish the harmful compounds. Many methods and materials are used in heavy metal removal from water. Biosorption by plant leaves is a potent and environmentally alternative technique for heavy metals removal from water. This review article revises the most recent studies of biosorbents such as plants’’ leaves, plants’ seeds, barks, and agricultural wastes and their efficiency on heavy metals adsorption, like Lead. Cadmium, Mercury, Chromium, Arsenic, Copper, Zinc and Nickel. This literature revision draw the base line of our ongoing study which explores the removal efficiency of Moringa oleifera leaves on cadmium and the sorption properties of the plant Moringa oleifera Lam. leaves for decontamination of Cd at laboratory scale.