Characteristics of pipe corrosion scales in untreated water distribution system and effect on water quality in Peshawar,Pakistan

This study investigated the characteristics of iron corrosion scales in pipes at tube well, overhead tank, and consumers’ end in older untreated water distribution system in Peshawar city, Pakistan. Effect of water quality conditions on corrosion scales and that of scales on drinking water quality in such systems was also assessed by undertaking a comparison with new piped distribution systems. The scales were analyzed for chemical composition and morphology using X-ray diffraction (XRD), inductively coupled plasma (ICP), and a scanning electron microscope (SEM), while water quality was examined for physicochemical and biological characteristics. The main crystalline phases of corrosion scales were goethite, magnetite, siderite, and quartz. From tube well to consumers’ end, goethite increased from 36 up to 48%, quartz declined from 22 to 15%, while magnetite fluctuated and siderite disappeared. Elemental composition of scales showed the deposition of Zn, Al, Mn, Cr, Pb, Cu, As, and Cd with Zn (13.9 g/kg) and Al (3.6 g/kg) in highest proportion. The SEM analysis illustrated the presence of microbial communities indicating the formation of biofilms in the corrosion scales. The significant difference (P <?0.05) in levels of dissolved oxygen (DO), Cl^?, SiO₄^4?, electrical conductivity (EC), SO₄^2?, NO₃^?, alkalinity, hardness, and trace metals between old (DS-O) and new piped systems indicated their role in corrosion scale formation/destabilization and the effect of scale dissolution on water quality. In DS-O, EC, Cu, and Mn were significantly higher (P?<?0.05), whereas turbidity, EC, DO, and SiO₄^4? significantly increased from source to consumers’ end implying a higher dissolution of scales and lowered corrosion rates in DS-O to utilize SiO₄^4? and DO for iron oxidation.

     

Urban Flood Problems in Dhaka,Bangladesh: Slum Residents’ Choices for Relocation to Flood-Free Areas

This article applies a stated preference choice model to assess trade-offs that residents of two squatter settlements in Dhaka, Bangladesh might consider if they were given choices for relocation to flood-free areas. The respondents were asked to choose repeatedly from a set of choice cards, which displayed different configurations of financial incentives for relocation, such as free or inexpensive land, loans or nonrepayable grants, and provisions for temporary or permanent employment opportunities. The survey results indicated that despite extensive experience with flood problems, many residents of Mirpur and Vasantek found that certain configurations of economic incentives were not attractive enough for them to relocate to flood-free areas. At the same time, they would prefer a reduction in the risk of flooding at their current location. The economic incentives that would best assist in increasing voluntary relocation of residents from their current locations included free land, nonrepayable grants (Taka 20,000), and long-term employment opportunities. Further, differences in geographic location (i.e., Mirpur vs. Vasantek), income levels, and membership in neighborhood communities were linked with the tendency of residents to stay at their current location.     

The Shaping of Environmental Information in Social Media: Affordances and Technologies of Self-control

This article studies environmental information as it circulates in social media, specifically in personal blogs and microblogs. It rests on a thematic analysis of a selection of Swedish language, personal, everyday life environment blogs active during 2011 and 2012 and the social media applications connected to these blogs. Gibson's concept of affordances and Foucault's notion of governmentality are brought together to examine how material and technological affordances of social media and the structures of governmentality work together to engender a type of information on environmentally friendly living that is rooted in the conditions of the Web, together with a view of society which is structured around choice and individual responsibility. The article argues that information is woven into the texture of the social on every level, including everyday life practices, and hence social media, as tools in such practices, contribute to shaping the way in which information on environmentally friendly living is articulated, shaped, and filled with meaning.     

Biology and management of two important <Emphasis Type="Italic">Conyza</Emphasis> weeds: a global review

Weed management is one of the prime concerns for sustainable crop production. Conyza bonariensis and Conyza canadensis are two of the most problematic, noxious, invasive and widespread weeds in modern-day agriculture. The biology, ecology and interference of C. bonariensis and C. canadensis have been reviewed here to highlight pragmatic management options. Both these species share a unique set of biological features, which enables them to invade and adapt a wide range of environmental conditions. Distinct reproductive biology and an efficient seed dispersal mechanism help these species to spread rapidly. Ability to interfere strongly and to host crop pests makes these two species worst weeds of cropping systems. These weed species cause 28–68 % yield loss in important field crops such as soybean and cotton every year. These weeds are more prevalent in no-till systems and, thus, becoming a major issue in conservation agriculture. Cultural practices such as crop rotations, seed rate manipulation, mulching, inter-row tillage and narrow row spacing may provide an effective control of these species. However, such methods are not feasible and applicable under all types of conditions. Different herbicides also provide a varying degree of control depending on crop, agronomic practices, herbicide dose, application time and season. However, both these species have evolved resistance against multiple herbicides, including glyphosate and paraquat. The use of alternative herbicides and integrated management strategies may provide better control of herbicide-resistant C. bonariensis and C. canadensis. Management plans based on the eco-biological interactions of these species may prove sustainable in the future.     

Recycling of waste glass as a partial replacement for fine aggregate in concrete

Waste glass creates serious environmental problems, mainly due to the inconsistency of waste glass streams. With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal. The properties of concretes containing waste glass as fine aggregate were investigated in this study. The strength properties and ASR expansion were analyzed in terms of waste glass content. An overall quantity of 80 kg of crushed waste glass was used as a partial replacement for sand at 10%, 15%, and 20% with 900 kg of concrete mixes. The results proved 80% pozzolanic strength activity given by waste glass after 28 days. The flexural strength and compressive strength of specimens with 20% waste glass content were 10.99% and 4.23%, respectively, higher than those of the control specimen at 28 days. The mortar bar tests demonstrated that the finely crushed waste glass helped reduce expansion by 66% as compared with the control mix.     

Use of waste plastic in concrete mixture as aggregate replacement

Industrial activities in Iraq are associated with significant amounts of non-biodegradable solid waste, waste plastic being among the most prominent. This study involved 86 experiments and 254 tests to determine the efficiency of reusing waste plastic in the production of concrete. Thirty kilograms of waste plastic of fabriform shapes was used as a partial replacement for sand by 0%, 10%, 15%, and 20% with 800 kg of concrete mixtures. All of the concrete mixtures were tested at room temperature. These tests include performing slump, fresh density, dry density, compressive strength, flexural strength, and toughness indices. Seventy cubes were molded for compressive strength and dry density tests, and 54 prisms were cast for flexural strength and toughness indices tests. Curing ages of 3, 7, 14, and 28 days for the concrete mixtures were applied in this work. The results proved the arrest of the propagation of micro cracks by introducing waste plastic of fabriform shapes to concrete mixtures. This study insures that reusing waste plastic as a sand-substitution aggregate in concrete gives a good approach to reduce the cost of materials and solve some of the solid waste problems posed by plastics.     

Calibration and verification of a dissolved oxygen management model for a highly polluted river with extreme flow variations in Pakistan

A dissolved oxygen (DO) model is calibrated and verified for a highly polluted River Ravi with large flow variations. The model calibration is done under medium flow conditions (431.5 m³/s), whereas the model verification is done using the data collected during low flow conditions (52.6 m³/s). Biokinetic rate coefficients for carbonaceous biochemical oxygen demand (CBOD) and nitrogenous biochemical oxygen demand (NBOD) (i.e, K _cr and K _n ) are determined through the measured CBOD and ammonia river profiles. The calculated values of K _cr and K _n are 0.36 day^?1 and 0.34 day^?1, respectively. The close agreement between the DO model results and the field values shows that the verified model can be used to develop DO management strategies for the River Ravi. The biokinetic coefficients are known to vary with degree of treatment (DOT) and therefore need to be adjusted for a rational water quality management model. The effect of this variation on level of treatment has been evaluated by using the verified model to attain a DO standard of 4 mg/L in the river using the biokinetic rate coefficients as determined during the model calibration and verification process. The required DOT in this case is found to be 96 %, whereas the DOT is 86 % if adjusted biokinetic rate coefficients are used to reflect the effect of wastewater treatment. The cost of wastewater treatment is known to increase exponentially as the removal efficiency increases; therefore, the use of appropriate biokinetic coefficients to manage the water quality in rivers is important.     

Assessing the recycling potential of industrial wastewater to replace fresh water in concrete mixes: application of polyvinyl acetate resin wastewater

This study presents the use of industrial wastewater released from polyvinyl acetate resin manufacturing plant to totally replace the fresh water in concrete composites. Seventy-two laboratory prepared concrete composites were tested to investigate the effect of using various PVAW/C ratios of 0.30, 0.35, 0.40, and 0.45 on the slump, compressive strength, flexural strength, and dry density of the concrete mixes. Results indicated a slight to moderate increase in compressive strength and hard density values compared to those of the control concrete made with fresh water at 7 and 28 day curing. On the contrary, a reduction in the slump values of the PVAW–concrete was observed compared to the slump of the control mixes. However, the slump values increased with increasing the PVAW/C ratios. On the other hand, the waste material leaching test revealed that none of the PVAW toxic constituents was detected. The findings of this work would form basic information for recycling PVAW in concrete mixes and indicate a potential alternative for diminution the adverse effects on the environment posed by the hazardous effluent of the polyvinyl acetate resin industry.