Municipal Solid Waste Management through Sustainable Landfilling: In View of the Situation in Karachi, Pakistan

Experimental investigation and multi-performance optimization of the leachate recirculation based sustainable landfills using Taguchi approach and an integrated MCDM method

Landfill leachates contain harmful substances viz. chemicals, heavy metals, and pathogens, that pose a threat to human health and the environment. Unattended leachate can also cause ground water contamination, soil pollution and air pollution. This study focuses on management of leachate, by recirculating the rich, nutrient-filled fluid back into the landfills, turning it to a bioreactor, thereby maximising the performance parameters of landfills favourable for electricity production by the waste to energy plants. This study demonstrates a sustainable alternative method for utilising the fluid, rather than treating it using an extremely expensive treatment process. Further, it also experimentally investigates the effect of varying levels of five input parameters of the landfill including waste particle size, waste addition, inorganic content in waste, leachate recirculation rate, and landfill age, each at five levels, on the multiple performance of the landfill using Taguchi's L25 standard orthogonal array. Experimental results are analysed using an integrated MCDM approach i.e. MEREC-PIV method and statistical techniques such as analysis of mean (ANOM) and analysis of variance (ANOVA). The results indicate that the optimal setting of the input parameters is waste particle size at 9 ppm, waste addition at 80 Ktoe, inorganic content in waste at 2%, leachate recirculation rate at 250 l/day and landfill age at 3 years. Further, inorganic content waste is found to be the most significant parameter for the multiple performance of the landfill. This study presents a novel approach to produce input parameters for power plants which may enhance their profitability and sustainability.

Bioremediation of reverse osmosis concentrate generated from the treatment of landfill leachate

The moisture content of municipal solid waste (MSW) and local precipitation events lead to the leachate generation from MSW landfills. The high concentration of organic pollutants in landfill leachate (LL) makes it hazardous, requiring treatment before disposal into the environment. LL is most commonly treated by reverse osmosis (RO), which generates large volumes of concentrate known as RO concentrate. This investigation aims to stabilize the RO concentrate through an inexpensive and effective bioremediation strategy. A bench-scale aerobic suspended growth reactor study was conducted using three commercial conversion agents, namely EM.1, Bokashi powder, and coir pith powder. Overall bench-scale efficiency of 63% was achieved in this study. The onsite studies were conducted in 7.5-m3 artificial ponds with 46% efficiency amid atmospheric influences and constraints. The overall efficiencies of both bench and field-scale studies were derived by ascertaining the arithmetic mean of the individual efficiency of the following parameters: chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total dissolved solids (TDS). In contrast, the control pond with no conversion agents showed an increase in pollution concentration over the 100 days of retention time. The findings revealed that the investigated technology had a marginally lower evaporation rate and performed relatively well compared to traditional solar evaporation ponds. Moreover, the technology can be easily scaled-up and readily applied for RO concentrate treatment in MSW landfills.

Do information publicity and moral norms trigger waste-sorting intention among households? A sequential mediation analysis

Introduction

The quick pace of technological advancement and urbanization has led to a significant increase in waste production, severely damaging environmental quality and human health. The sorting of waste is a viable option to reduce environmental hazards and attain high recovery rates in the cities. This research extended the theory of planned behavior (TPB) by integrating information publicity (IP) and moral norms (MNs).

Methods

A conceptual model has been developed to explore the predictors of waste-sorting intention of households. The data from 361 Pakistani households have been collected using the purposive sampling method and analyzed via PLS-SEM.

Results and discussion

The study's results revealed that IP is important in creating awareness and establishing moral norms regarding waste sorting among households. The findings further confirm that MN, attitude (ATD), subjective norms (SNs), and perceived behavioral control (PBC) sequentially mediate between IP and WSI. The findings of the current study provides useful practical implications to the practitioners and academicians to combat environmental pollution.

Climate change adaption strategies in urban communities: new evidence from Islamabad, Pakistan

Pakistan is urbanizing at the fastest pace in South Asia, and if left unplanned, it will not only reduce adaptive capacity of its residents rather it will be a chaos for its residents. The aim of this study is to answer the question on how urbanites of Pakistan are coping with climate change and which part of the society required support to cope with changing climate? To answer this questions, this study conducted survey through a structured questionnaire, from the urban residents of Islamabad, to explore their coping mechanisms towards climate change. Survey collected information on demographic, social, economic, and physical aspects, using Hackman's Treatment effect model. The sample selection equation is conditional on the adaptations to climate change in the outcome equation. Main independent variables are income, age, education, and occupation. Selection equation is based on perceptions of individuals about climate change which contains dependent variables of changes in temperature of summers and winters, changes in rain fall pattern, fog, hailstorm, and information received from social media and peer groups. With the result of 57.55, the Wald test shows that overall, there exists goodness of fit at the 99 percent confidence level. The value of rho in the Heckman model is 0.40 which implies the Heckman model provides more consistent and more efficient estimates. The results are suggesting that increasing age enhances the likelihood of adaptations as the positive and significant coefficient of age implies that age has probability to adapt to climate change. The positive and significant coefficient of income, education, and occupation implies that urbanites have higher probability to adapt to climate change. Perception is the essential foundation of adaptation, and differences in perception can be transferred to the adapted strategies. Households that experience a greater variation in annual mean temperature are more likely to adopt any adaptation strategy to cope with climate change. Essentially, poverty encompasses the majority of the characteristics that reduce respondents' adaptation capacity and increase their susceptibility to climate change. The major contextual disparities were discovered across union councils in the form of financial, personal, social, physical, and natural capitals of families. Therefore, obligation is on government to offer greater support for individuals who are less affluent in terms of these assets. For this city, officials must offer subsidy schemes to less privileged and marginalized people of urban dwellers to enhance their adaptive capacity.

Greenhouse Gas Emissions from Beef Cattle Breeding Based on the Ecological Cycle Model

Over the past few decades, the supply of beef has increasingly become available with the great improvement of the quality of life, especially in developing countries. However, along with the demand for meat products of high quality and the transformation of dietary structure, the impact of massive agricultural greenhouse gas emissions on the environmental load cannot be ignored. Therefore, the objective of this study is to predict the annual greenhouse gas emissions of 10 million heads of beef cattle under both the ecological cycle model (EC model) and the non-ecological cycle model (non-EC model), respectively, in order to compare the differences between these two production models in each process, and thus explore which one is more sustainable and environmentally friendly. To this end, through the life cycle assessment (LCA), this paper performs relevant calculations according to the methodology of 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (2019 IPCC Inventories). The results have shown that the total GHG emissions of the non-EC model were almost 4 times higher than those of the EC model, and feed-grain cultivation and manure management were main emission sources in both models. The non-EC model produced significantly more emissions than the EC model in each kind of GHG, especially the largest gap between these two was in CO₂ emissions that accounted for 68.01% and 56.17% of the respective planting and breeding systems. This study demonstrates that the transformation of a beef cattle breeding model has a significant direct impact on cutting agricultural GHG emissions, and persuades other countries in the similar situation to vigorously advocate ecological cycling breeding model instead of the traditional ones so that promotes coordinated development between planting industry and beef cattle breeding industry.

Conceptualization of Bioreactor Landfill Approach for Sustainable Waste Management in Karachi, Pakistan

Finding a sustainable approach for municipal solid waste (MSW) management is becoming paramount. However, as with many urban areas in developing countries, the approach applied to MSW management in Karachi is neither environmentally sustainable nor suitable for public health. Due to adoption of an inefficient waste management system, society is paying intangible costs such as damage to public health and environment quality. In order to minimize the environmental impacts and health issues associated with waste management practices, a sustainable waste management and disposal strategy is required. The aim of this paper is to present a concept for the development of new bioreactor landfills for sustainable waste management in Karachi. Furthermore, this paper contributes to estimation of methane (CH4) emissions from waste disposal sites by employing the First Order Decay (FOD) Tier 2 model of the Intergovernmental Panel on Climate Change (IPCC) and determining of the biodegradation rate constant (k) value. The design and operational concept of bioreactor landfills is formulated for the study area, including estimation of land requirement, methane production, power generation, and liquid required for recirculation, along with a preliminary sketch of the proposed bioreactor landfill. This study will be helpful for stockholders, policy makers, and researchers in planning, development, and further research for establishment of bioreactor landfill facilities, particularly in the study area as well as more generally in regions with a similar climate and MSW composition.