Waste Water Treatment, solidwaste Engineering and management

E-waste is one of the fastest growing waste streams in developed as well as in developing countries. Due to the fact that the life span of computers has dropped in developed countries from six years in 1997 to just two years in 2005, and mobile phones have a lifespan of even less than two years, the amount of generated e-waste per year grows rapidly. This has
a major impact on developing countries as loopholes in the current Waste Electrical and Electronic Equipment (WEEE) Directives allow the export of e-waste from developed to developing countries (70% of the collected WEEE ends up in unreported and largely unknown destinations). The objective of this paper is to present trends in E-waste identification of
reasons for E-waste and suggest measures for E-waste management.

The use of wastewater in agricultural irrigation has the potential for positive and negative environmental impacts.With careful planning and management, the use of wastewater can be beneficial to the environment. Constructedwetlands are usedworldwideforwastewater treatment, and this study discussesthe resultsofthesewetlandsincold and moderateregions ofthe world.Results show a remarkable BOD5 removal efficiency (58.8–99.84% of the influent BOD5 concentration( , even though only 62% of these wetlands were constructed following the U.S. EPA guidelines. The constructed wetlands can help remove TSS up to a level that is compatible with the quality standards for most reuse application in irrigation of crops. These wetlands cannot provide a water reclamation solution from a microbiological quality perspective that can meet reuse quality standards for irrigation.In terms of acidity, the effluent from constructed wetlands in cold climate is appropriate for irrigation of all crops. As a result, for reusing constructed wetland effluent in irrigation, combined systems like WSP-CW system require complying with the standard effluent for reuse water

Keywords:
Constructed wetlands, feasibility, irrigation, removal efficiency, reuse water

Nigeria just likes every other country in sub-Sahara Africa is faced with solid waste generation and management. Solid waste is dump indiscriminately and seen in huge heaps on any piece of unused land, around buildings, drainage system, institutions, playing ground, roads side, and in the open market places in major cities and towns. Living with solid wastes littered around seems to be an acceptable way of life among the people in this part of the world. This research work reported intensive review on solid wastes generation and management in this region using Nigeria as a case study. The application of knowledge of solid waste generation and management approach is crucial for inculcating a change of attitude towards improving the management of generated solid waste in this region. From the review, it was observed that biodegradable solid waste that can be managed via the biogas technology and landfill technology have the highest percentage fraction while the remaining fraction that comprised of non-biodegradable and combustible solid waste can be managed via other technology such incineration, gasification, pyrolysis, etc. Besides, the inefficient management of generated solid waste by individuals, households, institution, consumers and waste management companies can be attributed to inadequate information on waste management benefits, insufficient academic research and industry linkages, financial constraint, economic constraint, cultural constraint, lack of planning and projection, social constraint, lack of producers' involvement in waste management as well as poor implementation of government policies and lack of comprehensive legal framework.

A field experiment using squash crop (Cucurbita pepo L.) variety askandrani was carried out at the Experimental Farm, Faculty of Agriculture (Saba-Basha), Alexandria University, Egypt during 2014 growing season. The farm is located at Abees region 31˚10.102′ N and 29˚58.085′ E with altitude of (-5m) below sea level. The present research studied the effect of soil amendments such as animal manure, bagasse, sulphur and gypsum with different combinations on the physical and chemical properties of saline-sodic soil and also its effects on squash growth and fruit yield characteristics besides the nutrients content of leaves and fruits. Seventeen treatments of soil amendments were applied to soil and mixed thoroughly with the upper 30 cm layer. The squash was sowing at 13 th October. Seeds were sown at 4-5 seeds in each hill with spacing of 0.25 m within each row and 0.6 spacing, and then thinned to one plant after 2 weeks from sowing. After emergence, the plots were irrigated by the furrow irrigation method. Harvesting was at 6, 11 and 27 December. Vegetative growth, yield and yield components and nutrients content of leaves and fruits were measured. Also, physical and chemical characteristics were determined. The obtained results revealed that all vegetative characters (leaf fresh and dry weights, leaf water content, gross plant weight and chlorophyll contents) were not affected by amendments treatments. The highest values were attained with animal manure (24 ton/ha) plus gypsum (4 ton/ha). The maximum squash fruit yield characters (fruit diameter, fruit length, fruit weight and fruit yield) were attained with animal manure plus gypsum treatment. The value of squash fruit yield was significantly increased with soil amendments treatments and the maximum value was attained with animal manure plus gypsum treatment (6954.0 kg/ha, it is accounted as 271.30% over the control treatment. All macro-and micro-nutrients content of leaves and fruits are significantly affected by application of soil amendments, especially animal manure plus gypsum treatment. The soil physical properties such as bulk density, mean weight diameter, geometric mean diameter, structure coefficient and geometric standard deviation are significantly improved by applications of soil amendments. The soil stability index (SI), Kelly's ratio (KR) and permeability index (PI) indicates an excess level of sodium and the soil qualified to alkali hazards. Thus soil has problem about the water permeability. All soil chemical properties including the nutrients availability were improved as a result of application of different soil amendments, especially animal manure plus gypsum. Also, soil available macro-and micro-nutrients were improved with application of soil amendments. It is clear that animal manure plus gypsum treatment is the best treatment for improvement of the sodic soil.

Rose bengal (RB) is xanthene dye, that extensively used in dyeing, printing industries and also as an insecticide.It has severe toxic effects on the human health. Although there are many studies on adsorption/photodegradation ofrose bengal using different reductants, it is of interest to explore the environmentally benign Fe(III)montmorillonite (Fe(III)–Mt). Fe(III)–Mt was interacted with rose bengal (RB) solution at different pH (5-10), temperature (0-40°C) and
solid-to-liquid ratio. The concentration of RB removal was estimated from its absorbance at λmax = 545 nm using UV-Vis spectrophotometer. In general, the dye removal was rapid in acidic pH and increases with temperature up to 50°C. A complete reduction through adsorption occurred within 3 min at pH 5 and 6. The time taken for complete adsorption at 0°C, 30°C and 40°C are 7 min, 5 min and 3 min respectively. The adsorption followed by immobilization of dye on the spent clay mineral was evident from FT-IR and FESEM/ EDX analysis. This adsorption process can be easily scaled-upfor real system applications.

The surface water solid stuff disintegration system is a device that can be easily adapted to the boats very easily. It mainly consists of two conveyer system and a wide opening which is specially designed such that it will promote the easy entry of algae or waste into the conveyer when the boat is moving, which is fitted on the front side of the boat. The two conveyors are kept in such a way that the primary conveyor stays up the water surface and the other stays below the water and when the boat moves through the water, solid stuffs will be forced into the opening and is further forced in by the motion of the conveyer. Both the conveyors move in opposite direction such that it offers more easy movement of waste materials. The conveyor's movement allows the algae to fall into a collecting chamber. The conveyor will be powered by an engine or a powerful motor. The opening where the algae enters will be slightly narrowed in the inside region. Then the algae in the collection chamber is either disintegrated or crushed to smallest size possible. The crushed algae which is dumped offshore is further processed to get organic manure, bio diesel etc.

Colloidal gas aphrons (CGAs), first described by Felix Sebba in his book Foams and Biliquid Foams-Aphrons in 1987, consist of a system of spherical microbubbles with diameters mostly above 25 μm and classified as kugelschaums (ball foam). They possess some colloidal properties and can be pumped at uniform rate through pipes and channels, much like liquids. Also, they have high stability due to very small size and thick surfactant shells. Research work published over the past two decades indicate effective applications of CGAs for clarification of particles and microorganisms, protein separation, gas and nutrient transfer and pollutant separation from water and soil matrices. In this review paper, the techniques for generating CGAs and their application to pollution abatement are discussed. Some mineral separation processes by CGA flotation have also been reviewed because of their relevance to contaminant removal processes. The CGAs were found to function on the principles of bubble entrained floc flotation, electrostatic and ionic interaction, diffusion of entrapped gas and hydrophobicity of the pollutant particles. Two tables have also been provided to present a comparative overview of the generation technologies and the effectiveness of pollution remediation techniques. © 2012 Society of Chemical Industry.

http://onlinelibrary.wiley.com/doi/10.1002/jctb.3691/full

Reducing the environmental risk of soluble P loss from sludge-amended soils is essential for increasing soils
capacity to utilize sewage sludge beneficially. Fresh dewatered anaerobically digested sewage sludge (FSS), stabilized
with ferrous sulphate (FeSul–SS), calcium oxide (CaO–SS) and aluminum sulphate (alum–SS), each at
three chemical-to-FSS ratios, or by composting (BSC), was applied to alluvial soil at rates of 150 and 300 mg P
kg−1 soil. Changes in P phytoavailability in comparison to KH2PO4-amended soil were probed during 100 days
of incubation by a P-bioassay and were compared to the concentration of water-soluble P (WSP) and Olsen-P.
P phytoavailability was notably linked to the incubation duration and the stabilization process. In general, P
phytoavailability at equal P-addition rates was KH2PO4 >>alum–SS>BSC≥FSS>CaO–SS >>FeSul–SS; and it
was positively related to the added P rates, although with quite different patterns among the various sludge
products. The concentration of inorganic WSP (WSPi) extracted from the soil increased following the application
of FSS or BSC, and additional P mineralization further increased its concentration during incubation. In contrast,
in most cases the chemically stabilized sludges, especially the FeSul–SS, showed considerably reduced inorganic
WSP concentrations relative to the untreated soil. The total WSP, Olsen-P and organic WSP (WSPo) positively
correlated to P phytoavailability, indicating thatWSPo plays a role in plant P utilization in these soils. It is concluded
that all the chemically stabilized sewage sludge studied effectively controlled WSPi in soil while still supplying
P to support plant growth.

Waste streams generated by electroless copper plating in the printed circuit boards manufacturing industry often contain copper complexed by strong chelating agents such as EDTA. The consequence of metal complexation by chelating agents is that alternative treatment to chemical precipitation is often necessary to achieve the low metal concentrations required by increasingly stringent environmental regulations. This paper examines the feasibility of using activated carbon to remove EDTA-chelated copper(II) species as well as free copper(II) ions from aqueous solution. The adsorption characteristics of copper(II) and EDTA-chelated copper(II) on two granular activated carbons prepared from coal and coconut shell were evaluated. Adsorption equilibrium data of copper(II) on the two carbons corresponded well to the Langmuir model. The coconut shell-based carbon exhibited a greater adsorption capacity for copper(II) than the coal-based carbon under similar experimental conditions. Solution pH had a considerable influence on copper(II) adsorption by the two carbons. Low adsorption levels of copper(II) at pH 3 and high adsorption levels in the pH range of 4-6 were observed. However, a reverse adsorption trend was observed when the chelating agent EDTA was added to the copper(II) solution. Adsorption of EDTA-chelated copper(II) by the two carbons was higher at pH 3 than at pH 6. The contrasting adsorption behaviour of copper(II) ions and EDTA-chelated copper(II) species can be readily explained in terms of electrostatic interaction in that solution pH influences the surface charge of the carbons as well as the charge property of copper(II) ions and EDTA-chelated copper(II) species. (C) 2000 Society of Chemical Industry. Waste streams generated by electroless copper plating in the printed circuit boards manufacturing industry often contain copper complexed by strong chelating agents such as EDTA. The consequence of metal complexation by chelating agents is that alternative treatment to chemical precipitation is often necessary to achieve the low metal concentrations required by increasingly stringent environmental regulations. This paper examines the feasibility of using activated carbon to remove EDTA-chelated copper(II) species as well as free copper(II) ions from aqueous solution. The adsorption characteristics of copper(II) and EDTA-chelated copper(II) on two granular activated carbons prepared from coal and coconut shell were evaluated. Adsorption equilibrium data of copper(II) on the two carbons corresponded well to the Langmuir model. The coconut shell-based carbon exhibited a greater adsorption capacity for copper(II) than the coal-based carbon under similar experimental conditions. Solution pH had a considerable influence on copper(II) adsorption by the two carbons. Low adsorption levels of copper(II) at pH 3 and high adsorption levels in the pH range of 4-6 were observed. However, a reverse adsorption trend was observed when the chelating agent EDTA was added to the copper solution. Adsorption of EDTA-chelated copper(II) by the two carbons was higher at pH 3 than at pH 6. The contrasting adsorption behaviour of copper(II) ions and EDTA-chelated copper(II) species can be readily explained in terms of electrostatic interaction in that solution pH influences the surface charge of the carbons as well as the charge property of copper(II) ions and EDTA-chelated copper(II) species.

http://onlinelibrary.wiley.com/doi/10.1002/1097-4660%28200011%2975:11%3C1054::AID-JCTB315%3E3.0.CO;2-T/full

The continuous adsorption of lead ions from aqueous solution on commercial, granular, unpretreated palm shell activated carbon (PSAC) was studied. Effect of pH, flow rates and presence of complexing agents (malonic and boric acids) were examined. The breakthrough period was longer at pH 5 indicating higher adsorption capacity of lead ions at higher pH. Increase of the flow rate, expectedly, resulted in the faster saturation of the carbon bed. Presence of complexing agents did not improve adsorption uptake of lead ions. However, presence of malonic acid resulted in smoother pH stabilization of solution compared to single lead and lead with boric acid systems. The results on continuous adsorption of lead were applied to the model proposed by Wang et al. [Y.-H. Wang, S.-H. Lin, R.-S. Juang, Removal of heavy metals ions from aqueous solutions using various low-cost adsorbents, J. Hazard. Mater. B 102 (2003) 291-302]. The agreement between experimental and modelled breakthrough curves was satisfactory at both pHs. © 2007 Elsevier B.V. All rights reserved.

http://ac.els-cdn.com/S0304389407016640/1-s2.0-S0304389407016640-main.pdf?_tid=38ad17d0-025e-11e4-9d10-00000aab0f6b&acdnat=1404356623_7d3a2e8d154794cee46ba79a79cbfb61 
http://www.sciencedirect.com/science/article/pii/S0304389407016640

Adverse effect of the highly biorecalcitrant compound phenol to the environment is well established and its concentrations in industrial effluents vary greatly from 2.8 to 6,800 mg/l depending on the source. Fenton process effectively mineralises to CO 2 and H 2O but reported works consumed more reagents and require longer reaction times. Due to the strong interaction between the several predictor variables in the Fenton oxidation, response surface methodology was used to optimise the mineralization treatment. Efficient, faster and economical operating conditions for phenol removal were explored by investigating four parameters namely the concentration ratio of hydrogen peroxide to phenol-((H 2O 2):(Phenol)), mass ratio of hydrogen peroxide to ferrous ions-((H 2O 2):(Fe 2+)), initial phenol concentration - ([Phenol] o) and reaction time - (t r). The optimal TOC % reduction obtained were 35 and 88% for initial phenol concentrations of 100 and 5 mg/l, respectively. Reaction conditions corresponding to this phenol mineralization a reaction time of 20 min at ratios of 6 and 15 for [H 2O 2]:[Phenol] and [H 2O 2]:[Fe 2+], respectively. For mineralisation at 52.5 mg/l phenol concentration, the optimal conditions were 20 min, ratios 10 and 15 for the reaction time, [H 2O 2]:[Phenol] and [H 2O 2]:[Fe 2+], respectively. The soluble iron content of the analysed supernatant was found to be below the 15 mg/l (the maximum limit allowable for total iron discharges required by common regulative subscribed). This indicated that, the Fenton reagents were utilised during the peroxidation reaction evident from the almost near consumption of all Fe 2+ introduced in about 85% of the samples, thus, negating the need for immobilising the Fe 2+ catalyst or its removal by post treatment. The work proves that the optimized Fenton process can be potentially used for treatment of any phenol containing wastewater. © 2011 Academic Journals.

http://www.ajol.info/index.php/ajb/article/view/95907

The mineralisation kinetics of petroleum refinery effluent (PRE) by Fenton oxidation were evaluated. Within the ambit of the experimental data generated, first-order kinetic model (FKM), generalised lumped kinetic model (GLKM), and generalized kinetic model (GKM) were tested. The obtained apparent kinetic rate constants for the initial oxidation step (k 2 ′), their final oxidation step (k 1 ′), and the direct conversion to endproducts step (k 3 ′) were 10.12, 3.78, and 0.24 min-1 for GKM; 0.98, 0.98, and nil min-1 for GLKM; and nil, nil, and >0.005 min-1 for FKM. The findings showed that GKM is superior in estimating the mineralization kinetics. © 2014 Diya'uddeen Basheer Hasan et al.

http://downloads.hindawi.com/journals/tswj/2014/252491.pdf

Removal of Cr(VI) ions from aqueous solution was investigated using modified palm shell activated carbon. Low Molecular Weight Polyethyleneimine (LMW PEI) was used for impregnation purpose. The maximum amount of LMW PEI adsorbed on activated carbon was determined to be approximately 228.2 mg/g carbon. The adsorption experiments were carried out in a batch system using potassium dichromate K2Cr2O7 as the source of Cr(VI) in the synthetic waste water and modified palm shell activated carbon as the adsorbent. The effects of pH, concentration of Cr(VI) and PEI loaded on activated carbon were studied. The adsorption data were found to fit well with the Freundlich isotherm model. This modified Palm shell activated carbon showed high adsorption capacity for chromium ions. © 2010 Elsevier Ltd. All rights reserved.

http://ac.els-cdn.com/S096085241000221X/1-s2.0-S096085241000221X-main.pdf?_tid=f51c8916-2363-11e4-bb24-00000aacb35f&acdnat=1407987475_43bf713021931bbda2492ab1193f1a87 
http://www.sciencedirect.com/science/article/pii/S096085241000221X

Treatment of a wastewater containing high concentration of branced alkylbenzene sulphonates (123 to 250 mgL-1 MBAS) was achieved by means of an activated sludge system with recycle. The BOD, COD and MBAS levels of the recalcitrant wastewater were reduced by 87, 68 and 69 per cent, respectively. The high value of K(s) (111 mgL-a1) found for this recalcitrant wastewater indicates a lack of affinity by the enzymes to the substrate present. As such, biodegradation can be said to occur through a non-specific enzymatic action.

http://www.tandfonline.com/doi/abs/10.1080/09593338909384781#.U7-OkEC9gtE

Colloidal gas aphrons (CGAs) are micron-sized gas bubbles of 25-30 μm in diameter produced by a highspeed stirrer in a vessel containing dilute surfactant solution. These bubbles, because of their small size, exhibit some colloidal properties. In this work, CGAs were used to separate fine fibres from a lean slurry of cellulosic pulp in a flotation column. The pulp fibres were recovered as foamate from the top. Sodium dodecyl sulphate at a concentrations of 2.0 kg/m3 was used as a surfactant to generate the CGAs in a spinning disc apparatus. The results indicated that up to 70% flotation efficiency could be obtained within a short column height of 0.3-0.35 m. This technique can be applied to recover fine cellulosic pulp from paper-machine backwater. Colloidal gas aphrons (CGAs) are micron-sized gas bubbles of 25-30 μm in diameter produced by a high-speed stirrer in a vessel containing dilute surfactant solution. These bubbles, because of their small size, exhibit some colloidal properties. In this work, CGAs were used to separate fine fibres from a lean slurry of cellulosic pulp in a flotation column. The pulp fibres were recovered as foamate from the top. Sodium dodecyl sulphate at a concentration of 2.0 kg/m3 was used as a surfactant to generate the CGAs in a spinning disc apparatus. The results indicated that up to 70% flotation efficiency could be obtained within a short column height of 0.3-0.35 m. This technique can be applied to recover fine cellulosic pulp from paper-machine backwater.

http://ac.els-cdn.com/S0960852497001697/1-s2.0-S0960852497001697-main.pdf?_tid=402f21f4-0ca1-11e4-b35b-00000aacb360&acdnat=1405484923_24d92d1270932faec95b83369b8a57ad 
http://www.sciencedirect.com/science/article/pii/S0960852497001697

Researchers have implied that natural bioremediation in karst or fractured rock is unlikely to occur because of the lack of bacteria biofilm in karst aquifers. Hydrologic and geologic characteristics of fractured rock aquifers have been described as not being suited for natural bioremediation because of small microbial populations. If bioremediation in bedrock aquifers is dependent upon contact between surface-attached bacteria and contaminants, then bioremediation would be limited by the low surface area to volume ratio (SA/V) of karst aquifers. A quantitative basis, however, for accepting or rejecting the assumption that attached bacteria dominate the biodegradation process in karst conduits has not been shown. The objective of this research was to determine if free-living karst bacteria contributed as much to toluene biodegradation as attached bacteria. Two flow-through reactor systems were established to test the different biodegradation rates. Each reactor system consisted of four 1.24-liter cylinders connected together with glass tubing for a total open volume of approximately 5 liters. The second reactor system was similar to the open system except the cylinders were filled with acid-washed, circular glass spheres that increased surface area to volume ratio approximately fivefold compared to the open system. Rhodamine dye was used to calculate the different residence-time distributions in each system. A sterile control study established that less than 3 percent of the toluene was lost to abiotic processes. Next, raw water from a karst aquifer containing live, indigenous bacteria was pumped through each system for 5 days to establish a biofilm on the glass surfaces. Colonization of the surface was confirmed by microscope visualization before toluene was added to the systems. The resulting first-order rate constants were computed to be 0.014 per hour for the open system and 0.0155 per hour for the packed reactor system. If surface-attached bacteria were the main contributors to the biodegradation process and the SA/V ratio was increased fivefold, a significantly higher biodegradation rate should have occurred in the packed reactor. The results of this study indicate that the free-living bacteria indigenous to a karst aquifer contribute as much to the toluene biodegradation process as attached bacteria.