Solid waste management in Estonia

Estonia is a Baltic country, a small member state of the European Union (EU), with an estimated population of about 1.325 million. Estonia has highlighted a shift in its waste management model, less reliance on dumping waste in landfills to produce valuable energy from that waste. Construction of incineration facilities started in 2013, and after this step, there was a diversified effect on reducing municipal waste to the landfills. As for 2013, 2014 and 2015, a total waste of 14%, 8% and 5%, respectively, have been reduced.

The introduction of tax rates to landfills depends upon the type of waste. The rate increases if the waste dumped into the landfills is larger than the permitted quantity, established according to the Environmental Charges Act. This step also led towards the reduction of waste dumped to the landfills.Figure 1 shows the acceleration of the production of the largest part of waste in 2004 to the lowest part of waste produced in 2015. While Figure 3 depicts that Estonia increased its recycling capacity from 18% in 2013 to 31% in 2014 (Eurostat, 2013).

Solid waste management in Poland

Poland, also known as the Republic of Poland, is a part of Central Europe with an estimated population of about 38,645,240 people. Poland also used recycling as a means to reduce waste dumped on the landfills. Figure 3 depicts the recycling rates in Poland obtained in previous years. While Figure 2 reveals the difference in waste management in the last years and interprets that there is an increase in the recovery and recycling of waste while the amount of waste disposed at the landfills decreases (Eurostat, 2019).

Municipal Solid Waste management in United Kingdom

The UK is a large European country with an estimated population of about 65.6 million, which is expected to increase to 79 million by the end of 2039 (Statistics, 2017). The current government tries its best to maintain the natural environment of the United Kingdom in a better and safe state as they found it (Eurostat, 2013). Figure 5 shows the gradual decrease in waste production from 2004 to 2012. There was a slight increase in waste in 2015, but the overall waste generation was 20%, less than in 2004.

The government of the UK introduced a national waste management plan aiming to raise efforts towards a zero-waste economy. High quality recycling techniques are introduced through which waste material is recycled and recovered before going to landfills, this technique reduces the amount of waste in landfills. Figure 6 shows the pre-treatment of solid waste before landfilling (DEFRA, 2017).

Solid Waste in Karachi

Karachi is the largest metropolis of Pakistan, located in the southern province of Pakistan named Sindh. It is the most populous city in Pakistan and the fifth most populous city in the world. This city is considered a premier financial and industrial hub and centre of the country because this city plays a central role in the economy of Pakistan (Kwenda, Lagerwall, Eker, & Ruijven, 2022). Many well-known industries (textile, pharmaceutical, steel mills, automotive manufacturers) and small and medium sized industries are located in this city, making this city crucial for the economy of Pakistan,

Karachi’s social, economic and political conditions are disturbed, due to the ongoing pandemic which has ruined this city’s position. One of the main problems raised is solid waste, which has ruined this city’s position, and Karachi has become famous as the dirtiest city in Pakistan. This issue arises because of improper solid waste management by city and provincial authorities like KMC (Karachi metropolitan city) and SSWMB (Sindh Solid Waste Management Board) (Jerin et al., 2022). If not managed timely and effectively, it will raise various other unrepairable critical issues (Singh, Kumar, Mishra, & Kumar, 2022).

Municipal waste means any unproductive debris or garbage. The primary sources from which solid waste is generated in Karachi include household, commercial, industrial waste, institutions or office sweeping and street sweeping. The estimated waste generated in Karachi city is between 12000 to 15000 tons/day. Out of which, the garbage street picker picks 3105 tons/day of waste, and about 1350 tons/day is the amount of waste which housewives separate at the sources. The amount mentioned above of garbage is collected from five districts of the municipals corporation (DMCs) of Karachi and transported to KMC (Karachi Metropolitan Corporation) landfill sites, where this waste or residue is not properly disposed of or not segregated into its components (DEFRA, 2017). The waste generated in Karachi comprises of the material mentioned in Figure 7. Many challenges or factors affect the progress of solid waste management in Pakistan (Kissan Engineering). In 2021, PepsiCo launched Pakistan’s largest plastic waste collection program and collected and recycled over 16000 tons of plastic.This study aims to provide a facilitating framework for adopting smart waste management in the context of CE for Pakistan (Khan & Ali, 2022).

Bureaucratic hurdles

Solid waste management (SWM) has been the main agenda of the provincial government and many different political parties in Karachi for the last few years. The budget allocated for this purpose by Asian Development Bank’s (ADB) was about $400 million to work on Infrastructure and Service delivery Reform Program. Still, this budget was not allocated to the district and local authorities and became part of the corruption committed by government officials. The provincial government faces difficulty in this epidemic because of inappropriate policies and incompetent bureaucratic engines.

Lack of urban planning

The urban planning of Karachi city is not up to the mark, because the city is continuously expanding. The small disposal sites are located in the middle of many societies, and the major disposal sites also become a part of the city because of the expansion. Major disposal sites are few and cover about 9500 tons/day out of 12000 tons/day (Prinsen, 2022).

Inadequate waste management equipment

The waste management equipments used by the SSWB (Sindh Solid Waste Management Board) and KMC (Karachi Metropolitan Corporation) were outdated and not properly used for waste collection and disposal, creating many hurdles in the path towards waste management in Karachi. The identified zero waste strategy could benefit society and the environment positively and effectively. The mentioned factors or challenges target the primary waste management strategy to solve multiple criticalities of the region. The zero waste strategy could be beneficial and problem solving in managing waste (Zaman, 2016).

Zero Waste Strategy

Zero waste strategy is a focused approach of conserving all the resources through responsible production, consumption, reuse and recovery of product, packaging and materials without burning and with the least discharge to air, water or land that could cause an adverse effect on our environment and human health (Pant & Joshi, 2022). This strategy iterates along three cycles mentioned in the Figure 8. These combined cycles proposed a zero waste solution and economic business model. These zero-waste solutions and business models can give value to the availability of the steps into an arranged sequence of regenerative systems that benefit human health and nature (Tian, Liu, Yasemi, & Liu, 2022).

Ecological cycles

This cycle includes the application of basic laws and principles of Physics, Chemistry and Biology. It defines the effect of room temperature, pressures, etc., on the system’s functioning and easy access to the sources for effective system functioning (Gana, Babanyara, & Abdulkadir, 2022).

The zero waste model not only mention cycles but also provides economics business model with zero waste solutions which includes useful steps that can be implemented into every cycle as per the requirements. These steps are reduced, reuse, recycle and recovery to landfill (Korai, Mahar, & Uqaili, 2016).

Recycling

In Karachi, recycling activities are expensive and connected at all the stages of solid waste management. The private sector runs the recycling activities in Karachi, and recycling helps a lot in reducing the waste amount and earning environmental and economic benefits as this sector employs most of the poverty-ridden garbage pickers in Karachi. There are two main divisions of the recycling sector in Karachi (Muheirwe, Kombe, & Kihila, 2022).

• Packers and sweepers collect waste from street, community and society bins and disposal sites. After passing through several dealers and reaching the small-scale recycling industry, this stream deals with most of the poor quality waste, also known as the dirty stream. These include papers, plastic bags, broken glasses, plastic bottles, and bones.

• Separation of waste at the source of generation was sold to the buyers who travelled from place to place in search of good quality waste and reached small-scale recycling industries. This is called a clean stream (Younes et al., 2016).

Following is the technique used for recycling:

Mechanical recycling technique is used to recover plastic constituents of solid waste into a new product for reuse by using mechanical means. This technique becomes world known back in the 1970s. This technique helps recycle single polymer plastic because more complex the plastic structure would be, more challenging to recycle it mechanically. It is feasible to separate, wash and prevent waste for producing high-quality end products before recycling. The mechanical method involves several steps mentioned below:

• Shredding involves converting significant plastic parts into small chopped forms.

• Contaminant separation involves separating paper, dust and other impurities from plastic.

• Floating involves the separation of plastic flakes in a floating tank based on density difference.

• Milling involves the milling of single polymer plastic.

• Washing and drying involve washing plastic waste at the beginning. The actual washing occurs after the first if further treatment is required and usually can be done by water. Still, sometimes chemicals like caustic soda and surfactants are used.

• Agglutination involves collecting products for storage and further processing after adding additives and pigments.

• Extrusion involves the extrusion of plastic into strands and then production in palletised form.

• Quenching involves cooling plastic to be granulated and sold as a final product (Bikash & Ichihashi, 2022).

Recovery

Recovery involves the production of energy from solid waste.

• Solid waste samples collected from the various commercial and residential areas were used for quantification and composition. We weighed the components (plastic, paper, cloth, cardboard, food waste, glass, etc.) in the collected sample using physical balance. As per consumption equation,Equation 1 can be used for estimating quantities along with potential components by considering a 2.4% solid waste growth rate (Shahab, Anjum, & Umar, 2022).

• Various characteristics of solid waste, including moisture content (MC), total solids (TS), volatile matter (VM), fixed carbon (FC), ash content (AC), calorific value (CV), and element analysis, were determined by adopting standard methodologies. The theoretical biogas potential of the collected waste sample was estimated by using Equation 2.

• By considering various special characteristics of solid waste like Calorific value (CV), Ash content (AC), Fixed carbon content (FC), theoretical bio gas potential (TB_P), were estimated for different waste to energy technologies as per the procedures described below: (Bhat et al., 2022)

1 $X_{SW}=({Gr}_{SW} \times {Pq}_{SW} \times N)+ {Pq}_{sw}$

Whereas;

X_sw=Estimated quantity of solid waste

Gr_sw=Growth rate

Pq_sw=Present quantity of solid waste

N=Number of years

2 \begin{align*}&\!\!\!{TB_P=}\\&\!\!\!\!\!\!{\left(\tfrac{\left(\tfrac{4n+x-2y-3z}8\right)CH_4\;\times Sp.Wt\;of\;CO_2+\left(\tfrac{4n-x+2y+z}8\right)CO_2\times Sp.Wt\;of\;CH_4}{C_nH_xO_yN_z\;\times Sp.Wt\;of\;biogas}\right)\times1000}\end{align*}

Thermochemical conversion process

In this process, biodegradable and non-biodegradable materials contribute to energy output. Equation 3 andEquation 4 were used for estimating the energy recovery and power generation potential of Solid waste, respectively.

3 ERP=1.16\times NCV\times{SW}_{dq}

4 PGP=\frac{\left(0.048\times NCV\times{SW}_{dq}\times Y\right]}{1000}

Whereas;

ERP = Energy recovery potential(KWh/ton day).

PGP = Power generation potential(MW/ton day).

NCV = Net calorific value(kcal/kg).

SW_dq = Dry waste quantity.

Y = Thermochemical conversion efficiency. (N. et al., 2021).

Biochemical conversion process

In this process, a biodegradable portion of organic matter contributes only to the energy output. ; ; were used to estimate energy recovery and energy generation potential of Solid waste and methane generation, respectively.

5 ERP=MG\times NCV/0.042

6 PGP=\frac{\lbrack MG\times NCV\times Y\rbrack}{1008}

7 MG=\;{TM}_P\times Y_d\times OBF\times VM\times{SW}_{dq}\times1000

Whereas;

ERP = Energy recovery potential (KWh/ton day).

PGP = Power generation potential (MW/ton day).

NCV = Net calorific value (kcal/kg).

SW_dq = Dry waste quantity.

Y = Thermochemical conversion efficiency.

MG = Methane generation (m³/day).

TM_P = Theoretical methane potential(m³/kg VM).

VM = Volatile matter in percentage.

Y_d = Digestion efficiency.

OBF = Organic biodegradable fraction.

In solid waste, there are several degradable components (food waste and yard waste) and less degradable (plastic, wood, cloth etc), which is why, solid waste is a heterogeneous mixture. There is a need to develop different scenarios for optimisation of energy from solid waste shown in Figure 11 (Pal & Bhatia, 2022).

Whereas;

Mix-MSW=Mixed municipal solid waste includes leather, card board, rubber, paper, wood, textile, glass, ash, dirt etc.

Mix-OFMSW=Mixed organic fraction of municipal solid waste like wood,leather, paper etc.

BCs-MSW=Biodegradable component of municipal solid waste.

NBCs-MSW=non-biodegradable component of municipal solid waste.

NPCs-MSW=Non-putrescible components of municipal solid waste like wood, plastic, rubber, textiles and cardboard.

PCs-MSW=Putrescible component of municipal solid waste like food and yard waste.

CCs-MSW=Combustible component of municipal solid waste like leather, rubber, textile and wood.

RCs-MSW=Recyclable components of municipal solid waste like card board, paper, glass, metals and plastics.

Waste disposal area needs to be estimated on the prediction of solid waste generation. The capacity of the proposed landfill area can be estimated by using Equation 8.

8 landfill\;area=\frac{(R\times L\times P\times1.5)}{\rho_{bulk}\times H}

Whereas;

R=waste generation rate (kg/capita year).

L=landfill life span (years).

P=population (number of persons).

_{^\rho_{bulk}} waste bulk density (kg/m³).

H=height of the waste disposal at the landfill (m) (Bafail & Abdulaal, 2022).

Zero waste benefits for our environment

Reducing, reusing, and recycling can play a vital role in reducing the release of greenhouse gases and carbon content in the atmosphere. Zero waste strategy helps conserve natural resources and reduces the pollution caused by extrusion, manufacturing and disposal. Recycling focuses on keeping the waste out of landfills and incinerators and providing recycled material for the manufacturers to make new products instead of raw materials (Kwenda et al., 2022).

Zero waste benefits for the community

It helps to protect the community’s health and provides community building capacity. Zero waste practices like composting at the community garden, tool sharing and skills sharing to reuse and repair build capacity to reduce waste and cost. Zero waste practice ensures community health by reducing air pollution, land pollution and water pollution by keeping toxic gases and waste out of landfills and air (Bafail & Abdulaal, 2022).