Solid Waste Management: Current Scenario and Challenges in Bengaluru

Municipal solid waste management (MSWM) has become one of the significant environmental issues, particularly in developing countries. Bengaluru, the state capital of Karnataka, is one of the fastest growing cities in Asia. The Bruhat Bengaluru Mahanagara Palike (BBMP) with an area of 2190 km2 and a population of about 10.18 million generates around 5000 metric tons per day of solid waste at an average generation rate of 0.5 kg per capita per day (kg/capita/d). Presently, Bengaluru City is facing significant problems due to existing disposal practices of generated waste, incurring high cost due to lack of proper infrastructural facilities; also, the open dumping in the expanding zone of the city poses severe problems to the structures constructed on these old dumps. In the meantime, groundwater quality deteriorated due to improper leachate management. Intending to assess the possible impacts on the water environment and suggest a better waste management strategy, the present paper discusses the potential for handling the wastes, thereby reducing the amount of waste to be transported to the landfill. If this waste is used for energy and nutrient recovery, decentralization could also become commercially viable and address the technology-wise deficiencies in the existing MSWM system of Bengaluru City

Electrokinetic removal of heavy metals from soil

Removal of heavy metal ions from soils by electrokinetic treatment has several advantages. The extent of removal, however, is both soil specific and ion specific. The conditions to be maintained have to be established based on laboratory studies. With a view to maximize the removal of metal ions the trends of removal of heavy metal ions such as iron, nickel and cadmium form a natural Indian kaolinitic red earth during different conditions maintained in the electrokinetic extraction process are studied. A laboratory electrokinetic extraction apparatus was assembled for this purpose. Attempts are also made to elucidate the mechanism of removal of the metal ions from soil. The composition of the flushing fluid, voltage and duration of extraction are varied. While dilute acetic acid has been used to neutralize the alkalinity that develops at the cathode, EDTA solution has been used to desorb heavy metals from clay surface. Generally the extent of removal was proportional to the osmotic flow. Nickel and Cadmium are more effectively removed than iron. The percentage removal of Ni is generally proportional to the osmotic flow but shows sensitivity to the pH of the system. There is an optimum voltage for removal of metal ions from soil. The removal of iron was negligible under different conditions studie

Electrokinetic removal of heavy metals from soil

Removal of heavy metal ions from soils by electrokinetic treatment has several advantages. The extent of removal, however, is both soil specific and ion specific. The conditions to be maintained have to be established based on laboratory studies. With a view to maximize the removal of metal ions the trends of removal of heavy metal ions such as iron, nickel and cadmium form a natural Indian kaolinitic red earth during different conditions maintained in the electrokinetic extraction process are studied. A laboratory electrokinetic extraction apparatus was assembled for this purpose. Attempts are also made to elucidate the mechanism of removal of the metal ions from soil. The composition of the flushing fluid, voltage and duration of extraction are varied. While dilute acetic acid has been used to neutralize the alkalinity that develops at the cathode, EDTA solution has been used to desorb heavy metals from clay surface. Generally the extent of removal was proportional to the osmotic flow. Nickel and Cadmium are more effectively removed than iron. The percentage removal of Ni is generally proportional to the osmotic flow but shows sensitivity to the pH of the system. There is an optimum voltage for removal of metal ions from soil. The removal of iron was negligible under different conditions studied

Induced swelling of kaolinitic soil in alkali solution

Unexpected swelling induced in foundation soils can cause distress to structures founded on them. In this paper, the swelling of kaolinitic soils due to interaction with alkali solution has been reported. The induced swelling is attributed to the formation of new minerals, which has been confirmed by X-ray diffraction patters and SEM studies. To understand the effect of alkali concentration and duration of interaction, two series of consolidation experiments have been carried out. In series 1, the specimen were remoulded with water and inundated with alkali solutions and in series 2, the specimen were remoulded and inundated with same alkali solutions. A steep compression during loading cycle and no abnormal swelling during unloading cycle has been noticed for the specimen remoulded with water and inundated with 1 N NaOH solutions. The steep compression is due to the segregation or break down of clay minerals due to alkali interactions. In case of specimen inundated with 4 N NaOH solutions, abnormal swelling has been observed during unloading cycle of the consolidation test. New minerals are formed on interaction of soil with 4 N solution as confirmed by X-ray diffraction patterns. These minerals are known to have very fine pores and possess high water holding capacity. The differences in the amount of swelling of samples remoulded with water and remoulded with alkali solution are due to variations in the concentration of alkali and duration of interaction

Optimum lime content of fly ash with salt

The pozzolanic reactivity of fly ash, which plays an important role in its utilisation for geotechnical applications, depends on the reactive silica and the lime content. Fly ashes containing sufficient reactive silica but insufficient lime content improve strength on the addition of lime. The development of strength up to optimum lime content is particularly high. The formation of pozzolanic reaction compounds, which is responsible for improvement of strength, can be enhanced in the presence of sodium chloride. This can possibly be attributed to the higher solubility of silica and the formation of sodium silicate hydrate rather than calcium silicate hydrate. More voluminous pozzolanic compounds with higher water-holding capacity that can bind fly ash particles, leading to increased strength, are formed in the presence of sodium chloride. This paper examines the effect of sodium chloride on the free swell, liquid limit and strength of a lignitic fly ash obtained from Neyveli with different lime contents, and the effect on the optimum lime content. It has been shown that the free swell volume, liquid limit and strength of fly ash increase at every lime content in the presence of sodium chloride compared with lime content alone. The optimum lime content, obtained by any of the methods, has not altered in the presence of sodium chloride. This might be due to the formation of more pozzolanic compounds at every lime content