Ways to reduce coffee pollution: Improve sewage treatment facilities and adopt bioengineering

In a previous post, we discussed the common wastewater treatment methods to remove harmful chemicals from coffee affluence to reduce the pollution in water bodies. Similarly, we would be exploring sewage treatment facilities again, but for a different purpose - human waste.

If you think that coffee stops polluting the Earth after the post-processing phase; when it is shelved, brewed; thrown away, think again. A pollutant, that most people are addicted to, continues to reside within the human body and enters the water systems through the sewage systems when we use the toilet (Mowbray, 2022). This pollutant is none other than caffeine.

Caffeine has been termed as an emerging contaminant, which means that it can have "lethal impacts on human and wildlife endocrine systems, even if available at trace quantities" (Antunes et al., 2021). While Raj et al. (2021) found that the existing waste treatment facilities can remove between 64-100% caffeine from wastewaters, the wide range suggests that in many circumstances, caffeine can still escape the treatment process and into the waterways. As such, what are the available solutions to prevent disturbances in the ecosystem caused by caffeine discharge?

The video below briefly discusses the impacts of pollution caused by the caffeine expelled by humans, its impacts on the environment, along with some suggestions to reduce the caffeine discharged via the sewage systems:

Some key points include:

• Outdated or incapability of wastewater treatment facilities to fully remove the caffeine content in human waste.
• Climate change overwhelming sewage flows, which results in caffeine contaminated waters to spread even in the terrestrial ecosystems, negatively impacting human, animal, and plant health.
• Expanding and upgrading wastewater treatment plants and stormwater storage are viable solutions, but they require years before they are operational.
• Use nature-based solutions to detoxify wastewaters instead can be more effective and are quicker to implement.

Of interest is the final point. Nature-based solutions involve bio-engineering techniques to sieve out nutrients in the waters, typically with the help of plants, before the waters enter the waterways. While the video suggested plant-based solutions like rain gardens to purify and recycle waters, such solutions must still be carefully considered as the effects of caffeine on plants are still ambiguous (Diaz, n.d.; Mahaney, 2019).

Overall, careful planning and adequate time are key to implement both nature-based and man-made solutions to remove caffeine from wastewaters, to prevent pollution in the waterways, which could harm the health of those who dwell on Earth.

Coffee Farming: Pests begone

Pesticides are commonly used in conventional coffee plantations as farmers want to prevent infestations in their farms, which are costly and cumbersome to resolve. However, the reliance on pesticides can degrade the environment and be harmful to human health. 

Pests come in the form of insects and fungal diseases. While the best way to combat fungi is prevention, removing moist or rotting elements (dead wood, overwatering etc.), and copper spraying, farmers typically use pesticides that contain a mix of cypermethrin, deltamethrin, chlorpyrifos, carbaryl and malathion to remove insects (Boyd, 2015).

The chemicals in the pesticides are harmful to the environment in the following ways:

Chemical	Harm
Cypermethrin and deltamethrin	Highly toxic to fishes, bees, and aquatic insects. However, the chemicals are short-lived (generally less than a month) and have low volatility in soils (NPIC).
Chlorpyrifos	Highly toxic to birds, bees, and aquatic life. Chlorpyrifos can remain in soils or surfaces for up to months and can be transported to long distances when eroded into water bodies, or bioaccumulated in animals (NPIC).
Carbaryl	Highly toxic to earthworms, bees, and some aquatic life. Depending on the physical conditions, carbaryl can take from days to months to break down completely. While carbaryl is not as toxic as the previous chemicals, it is highly volatile in soils and water surfaces (NPIC)
Malathion	Highly toxic to bees, some beneficial insects, and some aquatic life. Its residence time and volatility are like the carbaryl’s. However, malathion is also highly volatile in the air (NPIC).

In light of the impacts that these pesticides can bring to the environment, organic certifications (examples), have been introduced to promote sustainability in coffee farms. Surprisingly, despite the lack of pesticide use in organic coffee plantations, these plantations have a 6-15% less chance of being infested by pests. A director of an organic coffee farm, Juan Vargos, explained that such positive results were due to preventive measures, using composts and hard manual labour (Perfect Daily Grind, 2019).

Overall, pesticides undoubtedly pollute the environment. An option to reduce pollution can be to go organic. However, whether farmers opt to use pesticides depend on considerations like the cost and labour involved.

Milk Coffee: Almond milk

People in different countries tend to be more receptive towards different alternative milk, and as such, we focus on North America, as almond milk has dominated the plant-based milk market, by accumulating  63% of the market share (Young, 2021). We seek to answer the question: what are the factors that contribute to pollution during almond milk production, and to what extent are they damaging to the environment.

In a report by Simar (2020), he summarised the production process of almond milk in the US:

Stage	Source	Extent of pollution (annual)
Production	Fertilizers	-          83.7 pounds of carbon monoxide (CO) -          59.5 pounds of ammonia (NH3) -          74.9 pounds of nitrogen oxide (NO) -          2.2 pounds of particulate matter (PM)
	Pesticides	Chemicals used depend on farm and operating scale
Processing	Harvesting machines	Greenhouse gases and leakages depend on farm and operating scale
	Almond shell cracking machine	Electricity source depends on farm and operating scale
After production	Transportation (semi-trucks)	-          286.6 pounds of CO -          163.1 pounds of NO -          2.2 pounds of PM10 -          6.6 pounds of PM2.5
	Packaging	Amount of plastic depends on farm
	Agricultural waste	-          24.3 pounds of CO -          2.2 pounds of NO -          4.4 pounds of PM2.5

Simar's findings suggest that the after production of almond milk is the most pollutive, as transportation, plastic, and agricultural waste generate the greatest amounts of pollutants.

Beyond the numbers, pollution from after production also occurs globally.

Firstly, besides transportation by trucks, the milk by sea as countries export them to the global markets. According to the International Maritime Organisation, shipping accounts for 1.056 million tonnes of carbon dioxide being released, and these amounts of gases are spread across the oceans and trapped within the atmosphere. Hence, contributing to global warming on a global scale.

Secondly, the ill-disposed plastic packaging may end up within the oceans, and be swept by the currents across the globe. Besides harming the animals physically when they mistake the plastics for food, some plastics that are degraded into microplastics can be consumed by the marine life, and be bioaccumulated and biomagnified. This eventually returns to harm human health when we consume seafood.

Lastly, the chemical leaches into the soil and can contaminate groundwater storage. On a regional scale, humans who depend on groundwater storage may experience health issues. On a global scale, agricultural waste can be transported by fish and physical elements and cause problems to health as well (Nagendran, 2011).

Alas, while almond milk can cause global-scale pollution, it is still more sustainable compared to dairy milk, as its primary and processing stages of production are less pollutive. Soucing locally produced alternative milk can further reduce our pollution footprint. However, sourcing local poses a problem for land-scarce countries like Singapore, as converting land to produce primary products incur high opportunity costs. What then can an alternative solution be?

Milk Coffee: Oat milk

Dairy milk tends to be the default option for white coffees. However, in 2019, there has been a 37% decrease in dairy milk consumers since the 1970s (Held, 2020), suggesting the rise in awareness of alternative milk options. Specifically, oat milk has been gaining increasing attention in the cafe scene due to its superior taste and texture against other alternatives. Sales of oat milk have risen 71% in just a year, from 2017 to 2018 (Aydar, Tutuncu, & Ozcelik, 2020). This poses the question: are there ramifications as consumers switch from dairy to oat?

Based on Poore and Nemecek's (2018) study conducted in 2013, oat milk uses significantly less land for production as compared to dairy, suggesting that the area for non-point source pollution via fertilizers and greenhouse gas emissions will be lower.

Figure 1: Environmental footprints of dairy and alternative milk. The data is based on Poore and Nemecek's study. Source: Ritchie, 2022.

This was supported by Roos, Patel, and Spangberg (2016), who did a more comprehensive study on oat milk production's impacts on the climate. Their study found that there is a 16-41% lower direct greenhouse gases emissions from energy and fertilizers usage, and the absence of livestock cultivation. However, the risk of eutrophication between oat and dairy milk appears to be similar given the same amount of land cultivated. Additionally, as oats are made of organic matter, the necessary process of digestion of oats by the enzymes produces 21-37% more ammonia emissions than dairy milk productions during storage and distribution. This increases the ecotoxicity impact on the environment. Fortunately, the ecotoxicity impact from oat milk production can be mitigated via the cultivation of grass-clover. This is difficult for dairy production as cows are ungulates and their hooves will compact the vegetation when they graze the fields, and barns limit the amount of space available for vegetation.

Overall, it seems that oat milk production is indeed a better alternative for the environment as compared to dairy milk, as lesser land can be used to produce the same amount of both kinds of milk. This means that oat milk generates fewer emissions and pollution risks than dairy milk. 

Also, those who enjoy specialty coffee, but are constrained by dietary restrictions, should definitely consider oat milk as its flavour is not overpowering, and it does not coagulate as compared to other alternative milk. Giving the coffee a better taste and smoother texture.

Milk Coffee: The heart of pollution in the dairy industry

Regardless if it is a flat white, latte, cappuccino, or a kopi-C, kopi, 3-in-1, what is are the two ingredients that are common in both drinks? Coffee, and milk. As I have drilled on continuously about the causes of pollution in the coffee industry, I would now diverge to a complementary product to coffee. Milk.

According to Dr. Weiss, nitrogen forms bulk of a cow's diet, and only about 33% of the nitrogen intake retains in the cow's system or secreted as milk. The remaining 67% gets excreted as manure. Due to the high nitrogen content emitted, manure was found to be the primary cause of pollution in the dairy industry.

Manure can pollute the atmosphere as it releases ammonia, which can react with other pollutants in the air to form NH4+. NH4+ compounds contain aerosols which are harmful to our respiratory systems, and contributes to global warming. They can also travel long distances, which increases the expands the area of vulnerability to a global scale. (source). However, the volatility of ammonia in the atmosphere depends on the:

-   surface area

-   air movement

-   temperature

-   pH

of the manure (Weiss). Hence, while the ammonia released into the atmosphere via manure is pollutive, complex conditions need to be satisfied for atmospheric pollution via ammonia to be considered as serious.

Besides polluting the atmosphere, manure releases ammonia which pollutes the hydrosphere too. Grossman (2014) quotes the EPA, who found that a cow can generate almost 25 times as much nitrogen form manure as humans can from sewage. This is concerning as the nitrogen either leaches into the soils, which gets incorporated in the waters, or it is directly disposed of in the waters. Nitrogen is a highly potent pollutant in waters as it is a limiting nutrient. In other words, it controls the growth of organisms in water bodies as there are other reactants in the waters that are more abundant. Excess nitrogen in waters can promote the growth of cyanobacteria and algae, which creates anoxic environments in the water bodies, threatening the aquatic life.

Hence, as the dairy industry contributes expansively to pollution, is it perhaps time to consider milk alternatives?

Milk Coffee: Our carbon footprint

There are many ways to prepare coffee at home. Drip bag, capsules, from a packet or pre-packed. They all taste different, but taste is not the only differentiating factor. Each choice has a different carbon footprint as well. 

A study conducted by the Department of Environment Quality in the state of Oregon compiled four different pieces of research that estimated the carbon footprint derived from the different preparations of coffee. The simplified version is of the following:

Image source: Heller, 2017.

From the study, it appears that milk-based coffee contributes the highest carbon footprint of about 0.22 to 0.24 kg of carbon dioxide equivalent per serving. As we know, milk comes from cows, and cultivating them contributes high levels of carbon emissions.

These emissions come from the clearing of land to cultivate the crops needed to feed the cows, and the cows themselves. It was found that cows are responsible for 15% of all anthropogenic greenhouse gas emission (Bryce, 2020)!

As we know, the clearing of land reduces carbon sinks, and the increase in dairy productions increases the carbon emitted and hence trapped in the atmosphere for at least 300 years. Alas, black coffee is not a perfect subtitute for milk coffee. This suggests that dairy production will stay, and if nothing is done, the existing atmospheric pollution will only worsen.

Hence, the question that remains is: how can we reduce our carbon footprint, besides switching from a cafe latte to an americano? 

Coffee Farming: Pesticide

Persticides are often used in coffee plantations and unfortunately, the amount of beans produced is directly related to the amount of pesticide used when cultivating the coffee trees (Suoto et al., 2018). de Queiroz et al. (2018) also found that pesticide consumption increased by more than 90% on a global scale, of which is partly derived from coffee. Pesticide use can have detrimental effects on humans and the environment, which we will touch on today.

de Queiroz et al. had did a study on the sustainability of pesticide use in coffee production. Out of the 59 active ingredients that are detected in pesticides, the team found that about 37% of ingredients are toxic to humans and animals, and 47% to the environment. The most common ingredients belong to the organophosphorus class and the pyrethroid class. Poisoning from organophosphorus pesticides are said to cause respiratory failures, seizures, muscle weaknesses, and comas (Vale, 2015), and pyrethroid pesticides are said to cause sore throats, abdominal pain and nausea (Bradberry et al., 2005). Environmental impacts include the acidification of soils and increasing resistance to weed species (Mulla et al., 2019).

Alas, pesticide poisoning is typical in countries producing coffee. In Brazil, the world largest producer for instance, the Human Rights Watch (2019) reported that exposure to pesticides is reponsible for at least 100 deaths in a rural school within the state of Parana alone, causing one to wonder the extent of impact pesticides can have on the whole of Brazil. 

Besides direct exposure, the impacts of pesticide pollution can be felt globally. Due to the trade networks established, chemical laden coffee beans are transported and consumed easily worldwide. Toxins may bioaccumulate within those who consume the coffee made from these beans, which endangers their health in the long run.

While there are detrimental heath impacts brought about by coffee farming, it is difficult for coffee addicts to abstain from coffee. Perhaps supporting organic or sustainbuluty certified beans would be the way to go.