Comprehensive assessment of solid waste management of a highly urbanized city in Metro Manila, Philippines during the COVID-19 pandemic

This study aims to gather primary and secondary data on the municipal SWM system of an urban area in Metro Manila during the pandemic to design targeted and effective measures to improve SWM practices and reduce plastic pollution. The study results show that the city’s waste generation rate is at 0.93 kg/cap/day, while the disposal rate is at 0.66 kg/cap/day. Most of the wastes in both generation and disposal are biodegradables, mainly consisting of food wastes. Among the plastic wastes, lightweight plastic bags were the most abundant in terms of weight. From total plastics waste generation, about 7% of them entered the water system; 5% retained on land and the remaining are burnt or in storm drains. An important recommendation from this baseline study is the effective segregation of biodegradable, recyclable, residual, and special wastes.


Introduction
The COVID-19 pandemic caused a rise in worldwide food and plastic packaging waste, resulting in an overwhelming increase in solid waste generation that surpassed the existing infrastructures for solid waste management (SWM) in most cities [1,2,3].The pandemic brought about drastic changes in lifestyles and consumption habits, which in turn affected material flows, waste recovery schemes, and waste circularity globally [4,5].The implementation of containment measures has impacted households in different job sectors and income brackets to varying extents [6].Many public transport, schools, and business operations have been closed.Households had difficulty accessing health services, and experienced food insecurity [6].The event also led to a boom in food and item delivery services and a subsequent increased demand for single-use plastic packaging and containers along with the sudden rise 1257 (2023) 012010 IOP Publishing doi:10.1088/1755-1315/1257/1/012010 2 of household consumption to healthcare items such as face masks [7].Sudden changes in waste amount and composition, especially in highly urbanized cities (HUCs), calls for the immediate need to design targeted and effective measures to improve current waste management practices, reinforce implemented waste regulations, and develop responsive and effective waste management systems [8].
In the Philippines, the Republic Act No. 9003: The Ecological Solid Waste Management Act of 2000 outlines the roles of the barangay and city/municipality regarding SWM [9].Ideally, biodegradable, and recyclable wastes from household and non-household sources should have a separate collection and treatment at the barangay's materials recovery facility (MRF).While only residuals and treated special wastes which should be collected by city are permitted in the sanitary landfill.However, even before the pandemic, challenges arose in implementing these roles and responsibilities in the highly urbanized cities (HUCs), particularly at the barangay level, due to constraints such as limited MRF space, insufficient budget allocation for biodegradable and recyclable waste collection, and the constant turnover of leaders every three years during elections [10].Consequently, the burden of waste collection falls on the city, but even at the city level, financial and technical constraints pose additional challenges [11].A certain HUC in Metro Manila has been grappling with SWM challenges and plastic leakage concerns for the past few decades [12,13].
In addition, the Law also mandates the local government units (LGUs) the updating of the 10-year solid waste management plan (SWMP) to identify strategies and long-term plans for service improvement.A key component in the plan is the waste analysis and characterization study (WACS) which determine the quality and quantity of solid waste that are generated and disposed of within an area, including information on the volume and weight percentages of constituent materials, as well as their volumetric equivalence, material types, and sources of generation.These sources encompass residential, commercial, industrial, and institutional sectors [9].It is important, however, to note that WACS data collected prior to the pandemic may not be applicable to the pandemic scenario, as there have been certain waste categories that experienced an increase in generation.Therefore, it is crucial to update the data to reflect the current waste generation patterns during the pandemic, utilizing internationally accepted tools such as the Waste Flow Diagram (WFD), Waste Wise Cities Tool (WaCT), and Wasteaware Benchmark Indicators (WABI).These tools will provide a comprehensive baseline assessment of SWM practices in the city.This study aims to gather primary and secondary data on the municipal SWM system of an HUC in Metro Manila during the pandemic to design targeted and effective measures to improve SWM practices and reduce plastic pollution.Specifically, the objectives of this research are to quantify the amount and composition of MSW that are generated from household and non-household sources as well as those received by the disposal facility using WACS guidelines, to generate waste and plastic waste flow diagrams using the WaCT and WFD tools, and to assess the overall integrated SWM system of the city through standardized benchmark indicators using WABI.

Study Area
The city's population exceeded 1 million in 2020 [14].It consists of numerous barangays, which are the smallest units of government in the country, and some of these barangays are situated near Manila Bay [15,16,17].The city is located downstream along the Pasig River, a significant river system in Metro Manila that connects Manila Bay and Laguna de Bay.This river system has been identified as a major contributor of ocean plastics globally [18].Due to the city's proximity to heavily polluted water bodies, along with the clustering of settlements in coastal regions [19,20], the escalating plastic waste poses a significant risk of environmental leakage.
Due to a non-disclosure agreement with the LGU, the specific study area cannot be disclosed.However, this study still provides a general overview of SWM practices, challenges, and potential solutions in the city.The findings and recommendations of the study will contribute to the broader understanding of SWM and aid in the making of sustainable waste management strategies for similar contexts.

Assessment Processes and Tools Used
Several guidelines and tools were utilized to comprehensively assess the SWM of the city.Philippine WACS guidelines provide data on the amount and composition of municipal solid waste (MSW) from both at source and end-of-pipe as basis for the development of effective SWM strategies by LGUs.While the internationally accepted tools of WaCT, WFD, and WABI are aligned with the Sustainable Development Goal (SDG) indicator 11.6.1 on MSW and essential to determine the amount of plastic leakage to environment.SDG indicator 11.6.1 is defined as percentage of collected and managed MSW in controlled facilities over the total generated MSW by the city.[21,22].

Waste Analysis and Characterization Study (WACS).
The Philippine WACS manual is developed by the Industrial Technology Development Institute (ITDI) of the Department of Science and Technology (DOST) and published by the National Solid Waste Management Commission (NSWMC).It is considered as the standard of all LGU-initiated WACS and the basis of all SWMP submitted to the Commission for approval [23].
The manual provides guidelines on two types of WACS which are to be conducted at two different points in the waste stream -at-source and end-of-pipe.At-source WACS, which is conducted through sampling directly from the household and non-household sources, is used when the waste generation rate, waste sources, and materials in the waste stream are to be determined for a Ten-Year SWMP.End-of-pipe WACS, which is conducted using samples just before its final treatment or disposal, such as samples from transfer stations, waste processing and conversion facilities, and landfills, is used when making feasibility studies for treatment and disposal technologies [23].

Waste Wise Cities Tool (WACT).
Waste Wise Cities Tool (WaCT) is formulated by UN-Habitat as a rapid implementation tool that evaluates a city's municipal SWM performance through evidence-based data which makes it coherent with other waste statistics systems to achieve 2030 agenda in waste management based on the SDG indicator 11.6.1 [24].Data points such as total generated MSW and total collected and managed MSW in controlled facilities are required to calculate SDG indicator 11.6.1.With these, the percentage of MSW that remains uncollected is identified.
WaCT is a seven-step process that shows cities how to gather data on generated, collected, and managed MSW in controlled and uncontrolled facilities.The tool consists of a guide to estimate the total MSW generation, a survey questionnaire to examine the MSW recovery process, and criteria for evaluating the environmental control level of the city's waste management facilities.The last phase develops forward links to other SDG indicators and introduces an evaluation using a WFD.It maps flow of plastic waste and quantifies leakage from the functional elements of SWM using quick and observation-based evaluation [24].

Waste Flow Diagram (WFD).
Waste flow diagram is a rapid and observation-based assessment tool for mapping waste flows and identifying potential leakage of waste specifically plastics in each aspect of the SWM system [25].It is a separate but a complementary tool to the WaCT [24].The WFD tool estimates the amount of plastic waste leakages to the environment as it was developed since ineffective waste management is considered as a major source of marine litter.It aids in visualizing the quantities of solid waste streams within a waste management system and is used in IOP Publishing doi:10.1088/1755-1315/1257/1/0120104 planning projects related to wastes, especially on decreasing marine litter.It is also used to monitor the effectiveness of waste interventions applied in an area [25].
WFD is a Microsoft Excel-based program that uses Sankey diagrams to map municipal waste flows and quantify the origins and fates of plastic waste entering the environment.The toolkit is meant to work in conjunction with SDG 11.6.1 by providing information on the sub-indicators and may be used for baseline assessment or scenario forecasting [25].

Wasteaware Benchmark Indicators (WABI)
. WABI is a standardized tool and was used to measure and analyze the municipal SWM and recycling system in the study area.Through the use of a standardized indicator set, the results of this study should aid in the decision-making for service improvements and in determining the strength and weaknesses of the system and compare the performance of the city against similar cities on a rational and consistent basis in order to relate applicable and efficient solutions [26].The tool is composed of three main parts that are sub-divided into different categories which tackle various aspects that influence a SWM system.Relevant supporting information is collected to provide background to the existing system in place in the city.Both the physical and governance aspects are broken down into specific components, with each component corresponding to a benchmark indicator.

Conduct of WACS
WACS was conducted at-source and end-of-pipe between October and November 2021 to determine the quality and quantity of MSW generated and disposed of in the city.Samples were taken from the households, non-households, and collection trucks for seven days each and these were characterized into different categories, weighed, and recorded.

At-Source WACS.
About 73 households, 66 commercial establishments, 67 industries, and 63 institutions were sampled.The number of household and non-household samples was beyond the minimum required samples using the Standard formula with a 10% margin of error (Equation 1).
Wherein, n = representative number of households and non-households N = total number of household and non-household generators z = 1.96 for 95% confidence level P = 20% standard of deviation = 0.20 e = 10% margin of error for HUCs, 1 st to 6 th class municipalities Equation 1.Standard formula for household sample [23].
The household and non-household cooperators were instructed to collect their daily waste and put it in the designated garbage bags provided.On the following day, the garbage bags were collected by vehicles of each district from the households from 7 to 8 am, and these were brought to their designated sorting areas.The samples were characterized according to waste categories prescribed by the WACS manual [23].Once sorted, each waste category was weighed and recorded for data processing and analysis.
The household waste generation rate (WGR) was calculated using the formula (Equation 2) given the number of sampling days of seven, and the total waste generated of households and total number of household members.The WGR for each type of non-household was calculated by getting the quotients of the total waste generated of the type of non-households, total units, over the number of sampling days (Equation 3).Combining the daily projected waste generation of household and non-household sources, the total daily MSW generation in the city was determined.

End-of-Pipe.
Nine collection trucks per day were sampled for seven days.Incoming trucks to be sampled were initially weighed using weigh pads.After the initial weighing, the trucks then proceeded to the sorting area where approximately 200 kg of wastes were collected from each truck.These wastes were initially stored in three density cube boxes with dimensions of 60 cm each to determine the average bulk density per truck.Bulk density is computed by dividing the total weights of the waste sampled by the total volume of the density boxes and number of sampling days (Equation 4).Wastes from the density boxes of each truck were divided using coning and quartering method.A quarter with a weight of approximately 50 kg were selected and sorted to the waste categories.Once sorted, each waste category was weighed and recorded for analysis.
Using the product of the average bulk density and the daily average volume of waste, the amount of waste disposed to the landfill was computed.The average volume of waste per day was calculated from the actual volume disposed in transfer station from 2020-2021 which was provided by the city.Then the waste disposal rate (WDR) was calculated by dividing the amount of daily waste disposed over the projected population in 2021.

Conduct of Field Activities using WaCT, WFD, and WABI Tool
An extensive series of field activities, which included site inspections, interviews, and tailgating of collection trucks were conducted for this study, upon completion of data gathering and review of related documents.A total of 23 facilities within the city were visited to observe and gain deeper understanding of the operations and practices related to waste management.The control levels of the junkshops and MRFs were determined using the criteria from WaCT.Potential plastic leakage factors in these facilities were also assessed using WFD.

6
Tailgating activities were conducted to observe the collection system of the city and to identify potential leakage factors of plastics during collection, transportation, and disposal.Two collection trucks were followed from their starting collection points until they completed their assigned routes to the disposal facility in the morning -one during biodegradable waste collection and one during nonbiodegradable wastes collection.Sources covered by the collection trucks represent all income groups and some establishments such as convenience stores, barangay halls, and among others.
A series of interviews with relevant stakeholders such as representatives from the LGU, junkshop operators, waste collectors, barangay officials, and waste pickers was conducted using survey forms, phone communication, video conferencing apps, and in person.The interview questions were based on the benchmark indicators as indicated in the WABI tool.

Limitations
The study area, during the conduct of WACS in wet season, was under the Modified General Community Quarantine (MGCQ) Alert Level 4.Under this status, the Inter-Agency Task Force (IATF) only allowed 30% capacity for outdoor services and 10% capacity for indoor seating for commercial establishments.Some offices were operational but with at least 20% on-site capacity.Some establishments such as schools, parks, recreational centres, and other facilities were already closed due to the restrictions and COVID-19 protocols being implemented.These factors were taken into consideration on the calculation of generation rates for non-households.

Waste Analysis and Characterization Study Results
The analysis and characterization of wastes reveal that the WGR in the city is presently 0.93 kg per capita per day, while the WDR is calculated at 0.66 kg per capita per day.The majority of the generated and disposed wastes consist of biodegradables, with majority of food wastes.Notably, plastic bags, which are lightweight in nature, are one of the most abundant plastic wastes observed in both generated and disposed waste.

At-Source Generation.
The daily total amount of waste generated by the city is about 1,750,508 kg or 1,751 tonnes, or equivalent to 0.93 kg/cap/day.About 64% of the wastes are from the residential while 29% are from the commercial establishments.The remaining 7% constitutes the contribution from industries and institutions.
The calculated WGR of the city is within the range of the synthesized waste generation rates from the Solid Waste Management Status Report of the Department of Environment and Natural Resource (DENR) through Environmental Management Bureau (EMB) in 2018 [27] (Table 1).Compared with the national average of 0.4 kg/cap/day, the WGR of the city is approximately two times higher.Possible reasons for the higher WGR are likely due to the increase in consumption as well as the increase in the production and usage of plastics and healthcare products like face masks, face shields, and among others during the COVID-19 pandemic.1).About 930,686 kg of wastes are biodegradables in which food waste being the highest at 47% while 367,623 kg are recyclables of which are dominated by paper and plastic (Figure 2).The increase of paper and plastic recyclables such as plastic bottles, utensils, and containers by 75,000 kg/day as compared to pre-pandemic data may be attributed to the boomed consumption of the Filipino households especially of paper and plastic packaging during the pandemic.Despite the need to manage these kinds of waste during the pandemic, the fear that reusable products could carry the virus and increase transmission prevails.
Residual wastes are 355,398 kg with 205,402 kg for those with potential for recycling and 149,996 kg for disposal.Most of these wastes are made up of plastic bags at 5%, and textiles, clear sachets, and laminates at 2% each.High proportion of these plastics may indicate high single use plastic usage in the city.Special wastes, which include COVID-19 related health care wastes such as masks and gloves are found to be at 96,801 kg which comprise around 4% of the overall waste generated (Figure 2).Comparatively, the pre-pandemic special waste production in 2015, accounted for merely 0.08%, illustrating a fiftyfold surge in medical waste consumption attributable to the COVID-19 pandemic.This sudden increase of the healthcare waste during the pandemic is also observed in other studies [30,31].

End-of-Pipe Waste Disposal.
The average bulk density of the waste of the city was calculated at 238.05 kg/m 3 .It was observed during sampling that whether the day is a biodegradable or non-biodegradable collection, the wastes were still mixed as supported by the close values of bulk waste density per day.This may signify that the segregation policy in the city is not being strictly followed.
A total of 1,240,146 kg of waste is estimated to be the daily amount of waste being disposed of to the landfill.The WDR is then calculated at 0.66 kg/cap/day, which falls within the range of 0.33-0.67kg/cap/day for the WDR of HUCs [32].

End-of-Pipe Waste Composition.
Wastes samples from the End-of-Pipe WACS are comprised of about 57% of biodegradable wastes (Figure 3).Food wastes make up majority of these biodegradables at 31%. High proportion of food wastes could have led to the high consumption of food in residences and establishments in the city, as well as the high moisture content observed in these samples.Although the Law mandates the utilization of biodegradable waste, particularly food waste, for composting at the barangay level, it has been observed that these wastes are often mixed with other types of waste and ultimately disposed of in landfills.
Recyclables were found at 10% with plastic and paper being the highest at 4% each (Figure 3).These materials should also be diverted to recovery facilities.However, the lack of such facilities and the low market prices during the pandemic have resulted in some recyclables being considered low value and ultimately not effectively recycled.Residuals with potential for recycling comprise about 20% of the entire waste sampled (Figure 3).Textiles mostly make up these residuals at 7%, followed by plastic bags and clear sachets at 4% each.Residual wastes for disposal make up 9% of the waste sampled with most diapers and napkins at 5%.Special wastes comprise about 4% of the end-of-pipe wastes (Figure 3).Most of these wastes are comprised of bulky waste at 2%.Healthcare and hazardous wastes including the face masks were found at about 1% each wherein these wastes should be treated first before the final disposal.

Waste Wise Cities Tool (WaCT) Flow Diagram
A total of 1,751 tonnes of wastes are generated daily in the city in 2021 (Figure 4).About 64% of these wastes are generated from the households while the remaining 36% are from non-household sources.
The collection rate is determined to be at 86%.All the collected wastes are managed in both controlled and uncontrolled recovery facilities with 206 tonnes of wastes go to the controlled facilities such as registered junkshops and materials recovery facilities while the remaining 26 tonnes of wastes go to the uncontrolled facilities such as informal/unregistered junkshops.With these numbers, the recovery rate of the city is only about 13%.
A total of 1,266 tonnes of wastes ends up in the disposal facility including the 26 tonnes rejects and residues from the recovery facilities.This signify that most of the generated waste still end up to the landfill.By comparing the findings of two cities or provinces with similar populations [31] to the WaCT results of the study in the HUC in Metro Manila, it was revealed that the city under study had the lowest waste recovery rate, amounting to 13%.This rate is significantly lower than Chonburi Province, Thailand, which stands at 26%, and slightly higher than Seremban City, Malaysia, which stands at 11%.These results highlight the need for enhancing waste recovery measures in the city.These findings emphasize the urgent need to enhance waste recovery measures in the city.Furthermore, it is worth noting that all three areas demonstrated comparable rates of food waste generation, ranging from 0.26 kg/cap/day to 0.29 kg/cap/day.Additionally, the city under study exhibited the highest amount of uncollected waste, which contributes to plastic leakage, totalling 191 tonnes per day, in contrast to Chonburi Province's 44 tonnes per day and Seremban City's 21 tons per day (Table 2).Overall, about 13% of the total generated plastic wastes are unmanaged.Approximately 7% or 7,686 tonnes of plastic waste end up in water systems, 5% or 5,223 tonnes remain on land, while the remaining of about ~0.1% are either burned or found in storm drains (Figure 5).
From the collection services and disposal facilities, notable amounts of potential plastic leakages were detected, amounting to approximately 2,910 tonnes and 7,609 tonnes, respectively.Three percent of the plastic wastes are calculated to leak during collection, while 10% of the plastic wastes are estimated to leak in the disposal facility (Figure 5).Collection can be improved by ensuring that garbage bags are properly sealed and kept indoors to minimize the effects of external factors such as animal access, winds, and heavy rains.While the landfill can be analyzed for slope stability to determine the risk of a landslide and to recommend mitigating measures.Rehabilitation of fencing and acquisition of proper compacting equipment are improvements to significantly reduce plastic leakage in the disposal facility.

Wasteaware Benchmark Indicators (WABI) Results
The radar diagram visualizes the performance of the city based on the data collated from the field data on the WACS of the waste composition, waste pathways in the WFD, the levels of control in the WaCT Results of both the physical and governance aspects in the SWM of the city was summarized in a radar graph to determine which specific indicator should be given focus (Figure 6).
Both benchmark indicators 1.1 -Waste Collection Coverage at 86% and 2 -Level of Controlled Waste Treatment and Disposal at 84%, have fared well in the assessment.At 86% collection coverage, the LGU and its waste hauler can reach and collect majority of the wastes in the city.Informal waste collectors are also recognized in their contribution to the collection system (Figure 6).
Inclusiveness in the solid waste planning, management, and implementation for both users and providers are also evaluated in the assessment.High level of compliance is observed for both 4U -User Inclusivity at 92% and 4P -Provider Inclusivity at 85%.Presence of proper and easily accessible outlets of communication through the LGU's Facebook page, email, and contact numbers allows for a high level of engagement with the public.Further Information, Education, and Communication (IEC) campaigns are however still recommended for increased public participation.Proper bidding process, cost accounting, and contract audits also allows for good provider inclusivity in the SWM of the city.While the role of the informal sector in the waste collection, diversion, and recycling is recognized, they are yet to be fully and formally integrated into the system (Figure 6).

Figure 6. Radar Diagram of Wasteaware Benchmark Indicators in an HUC in Metro Manila
Benchmark indicator 6N -Adequacy of National SWM Framework is rated 67%.RA 9003 presents a comprehensive national framework on the SWM in the country.Although developments on the implementation of its provisions have also been observed in recent years, actual enforcement of the policies and corresponding local ordinances need to be more stringent.The presence of bills both in the senate and congress on the "Extended Producers Responsibility" is noted for the continued increase in the public awareness on SWM and various pollution related issues.
The performance of the LGU in the SWM of the city is also acknowledged for its medium to high level of compliance for benchmark indicators 6L -Local Institutional Coherence at 79% and 5F -Financial Sustainability at 75%.The department and all its relevant divisions show good organizational structure and institutional capacity, and proper city-wide SWM strategy and planning.
Benchmarks indicators for both 2E -Quality of Environmental Protection of Waste Treatment and Disposal with 42% rating, and 3R -Quality of Resource Value Chain with 33% rating needs however much improvement.Programs that would increase the rate of recycling of the total MSW both for dry recyclables and organic materials should also be given focus, as current rate is only at 16%.
Comparing the WABI results of this study with Quezon City, an HUC in Metro Manila with a population of nearly 3 million [34] in 2020, and Singapore City, a city-state in Southeast Asia known for its excellent waste management infrastructure and highest per capita waste recycling rate among 168 countries worldwide in 2016 [35], with a population of 5.7 million in 2020 [36], the HUC under study demonstrates superior performance in terms of User Inclusivity and Provider Inclusivity benchmark indicators.However, this superiority does not extend to the city's performance in relation to the physical component indicators, specifically the recycling rate, which falls behind both Quezon City and Singapore (Table 3).Furthermore, it is important to highlight that the studied HUC demonstrates better performance in terms of the quality of the 3Rs (Reduce, Reuse, Recycle) when compared to Singapore.However, it is worth noting that if the assessment were to incorporate data from 2021, significant improvements could be observed in both Quezon City and Singapore.The efforts of various government agencies, private entities, enterprises and NGOs in waste reduction, technological, and technical capacity building in the HUC under study are recognized.The actual performance of local resource value-chain however needs to catch up.The lack of detailing and standardization on the design of an MRF often results in these facilities only serving as storage instead of effectively reaching the deemed recycling and diversion process to take place in these facilities.Coordination between barangay MRFs as much as the creation of a centralized city-wide MRF is recommended for better coherence on either the processing of all wastes or the specialization in processing certain recyclables.As many junkshops often only trade recyclables that has higher potential monetary value, a lot of wastes with potential for recycling are mixed with other wastes for disposal.

Conclusion and Recommendations
The SWM condition within an HUC in Metro Manila during the COVID-19 pandemic was assessed using the Philippine WACS guidelines, as well as internationally accepted tools such as WaCT, WFD, and WABI.
The analysis and characterization of wastes reveal that the WGR in the city is presently 0.93 kg per capita per day, while the WDR is 0.66 kg per capita per day.The majority of the generated and disposed wastes are biodegradables which are mainly consisted of food wastes, while for plastic wastes, plastic bags dominate the composition.Uncollected wastes are approximately at 253 tons/day using WaCT wherein majority of the leaked plastic wastes are assessed to enter the water system or retain on land using WFD.WABI shows the governance aspect of the city performs well in terms of inclusivity and proactive policies.The physical components, however, lags with the recycling rate -only at 13%.An important recommendation from this baseline study is the effective segregation of biodegradable, recyclable, residual, and special wastes.Ideally, the waste collected by trucks and disposed of in landfills should consist solely of residuals, reducing the space and land required for landfilling and the associated transportation costs.In the case of the city under study, only 18% of the total waste generated is considered residuals, while the rest can be utilized.Utilization of food waste and recyclable plastics with potential for recycling would greatly decrease the number of wastes ending up in landfills and the environment.However, the successful implementation of such interventions requires the establishment and improvement of infrastructure, such as MRFs equipped with necessary tools and equipment, as well as the availability of markets to incorporate these types of waste into the circular economy.
The inclusion of informal waste sector into the formal waste management system should also be prioritized, as they can bridge the gap between uncollected waste and the overall recycling process within the current system.Although their role is acknowledged, their potential within the waste value chain needs to be elevated.
Additionally, it is recommended to develop a contingency plan in case of future pandemics to prevent the city from being overwhelmed by sudden increases in specific waste types such as food waste, plastic waste, and healthcare waste.
Overall, the comprehensive baseline assessment provided the whole picture of the current condition of the SWM of an HUC during the pandemic, revealing significant findings and identifying areas in need of intervention.It is recommended that further studies be conducted in other areas using similar guidelines and tools.

Figure 1 .
Figure 1.At-source waste composition from household and non-household sources.

Figure 4 .
Figure 4. Waste wise cities tool flow diagram of an HUC in Metro Manila during the pandemic in 2021.

Figure 5 .
Figure 5. Plastic waste flow in tonnes per year of an HUC in Metro Manila in 2021

Table 1 .
[27]hesized Waste Generation Rates in the Philippines in 2010[27]The amount of waste generated daily from each source are distributed to the general waste categories of waste (Figure

Table 2 .
[31] results in three cities in Southeast Asia[31].Plastic waste flow diagram with unit in tonnes/year was generated using the calculated quantities in different stages of the SWM of the city.In 2021, about 102,972 tonnes of plastic wastes are generated.Out of the total plastic waste generated, 97% or 100,277 tonnes are collected by both formal and informal waste collectors, leaving 2,695 tonnes/year of plastics categorized as uncollected.

Table 3 .
WABI Performance of this study, Quezon City, and Singapore.