• International Journal of Technology (IJTech)
  • Vol 15, No 5 (2024)

Vertical Greenery Systems as Microbial Air Quality Filters for Community Houses Located Near the Landfill Site

Vertical Greenery Systems as Microbial Air Quality Filters for Community Houses Located Near the Landfill Site

Title: Vertical Greenery Systems as Microbial Air Quality Filters for Community Houses Located Near the Landfill Site
Natasia Heindri , Ova Candra Dewi, Nandy Putra, Andrew Flynn, Tika Hanjani, Kartika Rahmasari

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Published at : 18 Sep 2024
Volume : IJtech Vol 15, No 5 (2024)
DOI : https://doi.org/10.14716/ijtech.v15i5.6958

Cite this article as:
Heindri, N., Dewi, O.C., Putra, N., Flynn, A., Hanjani, T., Rahmasari, K., 2024. Vertical Greenery Systems as Microbial Air Quality Filter for Community Houses Located Near the Landfill Site. International Journal of Technology. Volume 15(5), pp. 1361-1379

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Natasia Heindri Architectureal Sciences and Building Technology Research Cluster, Department of Architecture, Faculty of Engineering, Universitas Indonesia, Kampus Baru UI Depok 16424, Indonesia
Ova Candra Dewi 1. Architectureal Sciences and Building Technology Research Cluster, Department of Architecture, Faculty of Engineering, Universitas Indonesia, Kampus Baru UI Depok 16424, Indonesia. 2. Graduate Prog
Nandy Putra Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus Baru UI Depok 16424, Indonesia
Andrew Flynn School of Geography and Planning, Cardiff University, Glamorgan Building, King Morgan VII Avenue, Cardiff, Walles, United Kingdom
Tika Hanjani Architectureal Sciences and Building Technology Research Cluster, Department of Architecture, Faculty of Engineering, Universitas Indonesia, Kampus Baru UI Depok 16424, Indonesia
Kartika Rahmasari Architectureal Sciences and Building Technology Research Cluster, Department of Architecture, Faculty of Engineering, Universitas Indonesia, Kampus Baru UI Depok 16424, Indonesia
Email to Corresponding Author
Abstract
Vertical Greenery Systems as Microbial Air Quality Filters for Community Houses Located Near the Landfill Site

Rapid urban development, along with high population growth in Indonesia, has forced some communities to move away from the city center. At the same time, the city needs space for its waste, which is typically deposited in landfill sites. In both cases, the city outskirts have become favored sites for development. As a result, some communities now find themselves living adjacent to a landfill site and must cope with its air pollution. This study assesses the application of a vertical greenery system (VGS) acting as a microbial air quality filter for community houses located near the landfill site in Kampung Nambo in South Tangerang, Indonesia. Six types of plants were selected for analysis. The study found that Hedera helix was the most effective plant for filtering microbes from the air; the highest recording was reaching 717.3 CFU/m3 (day 10). The study also highlighted the presence of solar radiation, additional shading, and natural ventilation combined with the VGS help to improve air quality. Higher temperatures can reduce the microorganisms, thus impacting the number of bacteria and fungi. Every 1 W/m2 increase in solar radiation can reduce bacteria by 1.98 to 2.16 CFU/m3.  Furthermore, the insights of this study should encourage both governmental decision-makers and the broader community to reexamine the importance of vertical greening in settlements adjacent to a landfill.

Air quality; Dense settlement; Landfill; Vertical greenery system

Introduction

Indonesia experiences high humidity ranging from 55% to 100% along with daytime temperatures between 20°C to 32°C, and nighttime temperatures between 21°C to 27°C (Direktorat Jenderal Cipta Karya, 2020). These climatic conditions, together with Indonesia becoming one of the top twenty most polluted countries globally (The World Bank, 2022), can combine to produce potentially adverse health effects (Ahad et al., 2020). Additionally, the country's population has experienced a 211% increase from 1960 to 2022, with significant growth occurring in urban areas (The World Bank, 2022). A growing population and increasing consumption levels have resulted in more waste production. Thus, landfill sites have grown. Some landfill sites are located close to nearby communities that are also extending their boundaries, sometimes through informal settlements, and this too will have potentially adverse consequences for the environment and health. Despite a key regulation stating that settlements must be at least 500 meters away from landfill areas (Minister of Public Works Republic of Indonesia, 2013), housing settlements and landfill areas still become unavoidably “close neighbors”.

Building practitioners face challenges in considering future climate conditions in construction and retrofitting projects. Currently, there is a growing focus on developing models and gathering evidence to support the creation of more resilient buildings. One area of growing interest is in implementing Vertical Greenery Systems (VGS) to improve building envelope performance and address multifunctional benefits for dense settlements and nature (Ryan and Bristow, 2023; Rupasinghe and Halwatura, 2020; Hong, Ibrahim and Loo, 2019; Oluwafeyikemi and Julie, 2015).  A VGS is a vegetated wall system that can be applied to interior areas or building facades (Fernández-Cañero, Urrestarazu, and Perini, 2018). VGS helps to improve external and internal air quality (Megahed and Ghoneim, 2021). In addition, there is potential to enhance the "green feel" within communities by transforming ecologically barren walls into vibrant green spaces. This is especially beneficial in metropolitan areas (Shaharudin, Khalil and Saleh, 2019), where the layer of leaves that grows on walls acts as traps for reducing dust and particulate matter (Axmalia and Mulasari, 2020). Previous applications of VGS, such as in Pasir Gudang, Malaysia, show that it can enhance thermal performance while lowering air pollution (Ghafar et al., 2020). It has been claimed that if an inner-city area were greened on all potential facades, 4% of annual dust fall may be captured on the leaves (Köhler, 2008).

An early study on VGS by Zaid found that it can lower air pollution in a tropical context (Zaid et al., 2018). Subsequent work by Megahed and Ghoneim on spaces in densely populated residential areas discussed the use of VGS on building facades for natural ventilation, air quality management, thermal comfort, and green spaces (Megahed and Ghoneim, 2021). A vibrant debate is emerging on the applicability and efficacy of VGS in various settings (Bustami et al., 2018; Coma et al., 2017; Pan and Chu, 2016). Important developments have taken place in understanding thermal performance, energy efficiency, and plant variety.

        While other studies have made valuable contributions to the impacts of VGS on air quality (Yang et al., 2023b) and cooling (Yang et al., 2023a), less attention has been given to more marginal, densely populated communities where space is likely to be heavily contested and where environmental issues may be given only passing attention. Our study is to test if VGS could help improve the sustainability of waste concerns in our case study community and, more generally, around urban landfill sites in developing countries (Schlosser, Robert, and Debeaupuis, 2016). The contribution of our work, therefore, is to demonstrate that persuasive, evidence-based cases can be made for investments in VGS where they are sympathetic to community aspirations. VGS meets local community interests because it has minimal impact on space for homes and can help to improve air quality where there are concerns about respiratory health. Our study extends the role of VGS, which has typically adopted a planning-led approach (Fang, Li, and Ma, 2023) that underplays inequality in decision-making and outcomes. Kampung Nambo in South Tangerang City is selected as a case study to represent communities in a hot, humid climate. The research process is outlined in Figure 1 below. In Section 2, we develop our argument by combining insights into the negative health impacts of landfills with an understanding of VGS. This approach provides us with an opportunity to develop solutions that are more sensitive to the needs of the community and better address ongoing environmental problems. In Section 3 we outline our approach to data collection in our case study community and the selection of different types of plants to populate the box models that replicate potential VGS schemes. Section 4 reports on our results and shows the variability of different types of plants on air quality and thus supports our contention of the need for community-level analysis to maximize the benefits of green infrastructure investments. Finally, in Section 5 we draw together our insights and conclude that sympathetic plant selection plays a crucial role in the effectiveness of VGS. This is because, first different plant varieties perform an air cleansing function in variable ways at the local level; and second, where public and private funding is likely to be constrained community management of VGS will move to the fore, and communities need to be able to draw on their tacit knowledge of local plants to nurture their growth and care.

Figure 1 Study framework and keywords compilation

Experimental Methods


Literature review        
        In this section, we will discuss the issues surrounding landfill sites and their impact on the health and environment of local communities (Section 2.1). Since many landfill sites are expected to operate for the foreseeable future, it is crucial for neighboring communities to have the opportunity to enhance their air quality. We will explain our rationale for selecting specific plants in the study and present preliminary findings on the benefits of VGS (Section 2.2). Additionally, we will highlight how VGS can naturally assist in managing solar radiation (Section 2.3).

2.1. The impact of landfill sites, microbial air quality, and health

Landfill sites are formal locations to manage garbage responsibly for people and the environment. In practice, that may not always be the case. A landfill site near housing settlements and other sensitive locations, such as a market or a waterway, is considered unsafe and a threat to public health that needs to be adequately managed (Daniel et al., 2021). Moreover, waste decomposition generates methane (CH4) and hydrogen sulfide (H2S), which have a bad odor and may attract rats, while ammonia (NH3) causes respiratory illnesses, physiological abnormalities in the lungs, and elevated blood pressure (Axmalia and Mulasari, 2020). Along with chemicals, biological pollutants such as bacteria and fungi are transported by air circulation in the landfill area (Pepper and Gerba, 2015). As we are keen to emphasize throughout local conditions matter. In this case, local biometeorological factors such as temperature, pressure, relative humidity, wind direction, and the substance of waste and leachate create an impact on pathogenic agents’ ability to survive and multiply (Schlosser, Robert and Debeaupuis, 2016). In addition, in an equatorial or tropical environment, like that of Indonesia, building design places a high priority on managing the amount of heat transfer and ventilation (Othman and Sahidin, 2016).

2.2. Vertical Greenery Systems (VGS)

The VGS is categorized as a green facade (GF) or a living wall (LW) based on its construction type and diversity of plants (Fernández-Cañero, Urrestarazu and Perini, 2018). A GF commonly consists of vines and hanging plants applied to walls or balconies at different heights from the building, while a LW is a complex VGS suitable to support the growth of various plants and may be aesthetically pleasing (Fernández-Cañero, Urrestarazu and Perini, 2018). The installation of VGS with the living wall on the exterior has several patterns, such as a mesh and trellis system with planters (Cekic, Trkulja and Došenovic, 2020).

VGS can act as a natural air conditioner to absorb heat (Zaid et al., 2018). Natural ventilation, air quality controllers, and thermal comfort with green spaces are part of a VGS system on a building's facade in highly populated settlement areas (Megahed and Ghoneim, 2021). To improve visual comfort inside the home, VGS is additionally utilized as a shield from direct solar radiation (Stephenson et al., 2013; Funo, Yamamoto, and Silas, 2002). In short, depending on the scale at which it is implemented VGS can help mitigate local to wider Urban Heat Island (UHI) effects and reduce air quality problems.

Grass and ornamental plants in VGS, such as Cordyline fruticosa, Phyllanthus cochinchinensis, Nephrolepis exaltata, and ornamental plants like Philodendron burle-marxii can reduce heat and air pollution (Ghafar et al., 2020). While other plant species can also be used with VGS to filter airborne particles, like Dracaena deremensis, Neomarica gracilis, Philodendron cordatum, Schlumbergera truncata Hybrids, Monstera deliciosa, Nephrolepis biserrata, Hoya pubicalyx, and Cissus rhombifolia (Ghazalli et al., 2018). In addition, Hedera helix plants with a  20 cm thickness are not only capable of reducing heat but also acting as a wind barrier (Kraus, Žáková and Žák, 2020; Castellanos-Arévalo et al., 2016; Minister of Health Republic of Indonesia, 2011). The density of Passiflora plants is expected to impact the thermal experience (Widyahantari, Alfata, and Nurjannah, 2020).

Biochar is frequently used to boost the viability and efficacy of VGS (Kraus, Žáková and Žák, 2020). Based on a preliminary study from Puteri (2016), 59 plant species were examined to see which had the best pot systems for VGS. Alternanthera ficoidea stood out for having the highest index value for plants' capacity to produce the maximum supply of 18 O2/m2 with a leaf area of 44 cm2. As well as Codiaeum variegatum and other plants with an index of 12. In addition, Philodendron sp., with a leaf area of 363 cm2 and an index value of 8, performs well. It is, though, important to evaluate plant performance in a variety of local settings to be confident of their effectiveness, including their acceptability to communities and this will often mean that they are plants recognized locally. For our study, it involves examining the purification abilities of plants in close proximity to a landfill site, taking into account the hot and humid climate of Indonesia.

The anaerobic decomposition of microorganisms in landfills produces ammonia gas (NH3), which encourages the growth of bacteria, especially from organic waste (Yang et al., 2023a). According to the Indonesian health standard, the upper range for germ threshold with harmful fungi and bacteria is 700 CFU/m3 (Minister of Health Republic of Indonesia, 2011). International standards, such as the American Conference of Governmental Industrial Hygienists (ACGIH), are stricter and set a threshold of 500 CFU/m3. This more demanding requirement has become mandatory for some tropical countries, such as Brazil and Singapore (Castellanos-Arévalo et al., 2016). Another challenge for many landfill sites in Indonesia, including our case study, arises from biological activity brought on by sewer decomposition and stagnant water. This results in the formation of hydrogen sulfide gas (H2S), which has a strong odor (Elwood, 2021; Azima, 2016). Previous research has suggested that vegetation can be used to reduce high levels of bacteria and fungi in settlement areas near landfills (Fithri, 2021; Kumar et al., 2019). However, where land is scarce, as in our case study, there are limited opportunities to create traditional vegetation barriers.

A previous study by Rakhshandehroo mentioned that VGS is primarily applied on the façade with varying degrees of installation complexity to support building performance, such as reducing noise and insulating the building's envelope through solar reflection, heat transfer from the leaves and photosynthesis or evapotranspiration, among other things (Rakhshandehroo, Mohd-Yusof, and Deghati-Najd, 2015). Additionally, VGS has been found to reduce energy usage from 9.5% to 18% in commercial buildings and decrease the harmful effects of UV light on the building's (Rakhshandehroo, Mohd-Yusof, and Deghati-Najd, 2015; Sathien, Techato and Taweekun, 2013).

2.3. VGS and shading: reducing solar radiation

The range of optimal daylight intensity for housing in a tropical climate is about 3–7 W/m2 (DKI Jakarta Provincial Government, 2012). Lighting and ventilation are frequently connected. Therefore, external improvements, such as adding shade in the form of trees or air bricks and patterned tiles, can lower temperatures in settlements to between 18°C and 30°C and ameliorate internal comfort (Kusumawardhani, 2011; Minister of Health Republic of Indonesia, 2011). Well-planned shade can increase a city's aesthetic appeal lessen the consequences of heat generation (Macher, 1989) and reduce the risk of illness (Hollands and Korjenic, 2021).

In addition to lowering surface temperatures, VGS can also enhance air circulation, air quality, visual comfort, and indoor thermal conditions (Shuhaimi et al., 2022; Abdul-Rahman et al., 2014). However, the reality of the situation for many fast-growing urban areas in developing countries is that green space is continually being challenged, and so efforts to maximize the effectiveness of VGS need to pay particular attention to installation, maintenance, placement, density, and plant types (Abdul-Rahman et al., 2014). Little, though, is known about how VGS may work for poorer quality buildings and in more marginal communities. Our case study, therefore, fills an important gap in the literature.

Methodology

3.1. Case Study: Kampung Nambo, South Tangerang, Indonesia

South Tangerang City is one of the fastest-growing cities in Indonesia and is close to Jakarta. South Tangerang’s landfill is located in Kampung Nambo. The community next to the landfill site is home to 40% of the households in Kampung Nambo (Dewi et al., 2019). The area was chosen as a case study due to its environmental issues.

Figure 2 depicts the Kampung Nambo settlement with the landfill site visible in the background. Spanning an area of 2.5 hectares, the landfill receives approximately 300 tons of waste daily. The sheer volume of waste deposited has caused the landfill to surpass the height of the surrounding community, with reports indicating that the waste has reached a staggering 16 meters in height (Renaldi, 2020). It is claimed that “The foul smell emanating from the site has been reported as far as 6 kilometers away” (Renaldi, 2020).
Figure 2 The vicinity of Kampung Nambo Serpong with the view of a landfill as background

The average temperature is measured daily for the whole year during the study to be between 27.46°C and 28.04°C. Climate change is likely to lead to further increases in average temperature, making efforts to improve cooling within the community even more important. Like other tropical areas, local weather has a rainy season. This means that there is a high average annual humidity of around 80%. The average wind speed is between 1.44 and 1.57 m/s (BMKG, 2022) so might potentially blow air pollution into the neighborhood, which is only 500 meters away from the landfill.

3.2. Data Collection

Data sets were collected during the ‘shifting season’ in Indonesia - the time between dry and rainy seasons – for six weeks between March and April 2022. This study captured data from wet to dry seasons and our measurements took place during high rain precipitation, drought, and strong wind speed. The sampling was done outdoors, using one control box, and six VGS box models. Within the timeframe of the study, microbial air quality tests in the laboratory were done twice a week.

3.3. The Box Model

South Tangerang is at -6.31113, South Longitude: 106.65893, altitude 32.06 m, 105.20 ft. The area chosen for data collection was based on the accessibility of the likely contamination point nearest to the community (see Figure 3). A box model was developed to incorporate the VGS. This enabled us to investigate the amounts of bacteria and fungi, temperature, and humidity in dense populations next to the landfill. The box model with the VGS acts as a filter for contaminated air.

Figure 3 Experiment Box Model Placement in Kampung Nambo Serpong, RT 03 RW 04, South Tangerang City

3.3.1. Plant Selection

Six box models with different plants (boxes 1-6) and a box control (C) were set up. The control box had no plants but was fitted with louvre glass windows (see Figure 4).  The selected six plants that local growers offer are low-maintenance plants suitable for tropical conditions. They are Hedera helix, Alternanthera ficoidea, Nephrolepis cordifolia, Vernonia elliptica, Sansevieria trifasciata, and Philodendron sp. (Ghafar et al., 2020; Charoenkit and Yiemwattana, 2016). They encompass climber, creeper, succulent, and herbaceous plants. These plants were evaluated and ranked by consideration of climatic conditions such as humidity, temperature, wind speed, and solar radiation. The effectiveness of each plant as a microbial air quality filter was then ranked.