Algae and Environmental Sustainability: Friend or Foe?

What are Algae?

“Algae” is a very broad term that covers many different types of organisms that share the capacity of producing oxygen through photosynthesis. Biologically, they can be unicellular or multicellular, and have diverse characteristics, different sizes and different forms. However, generally speaking, they can be found in all range of aquatic habitats, including both freshwater and saltwater.

Harmful Algae Bloom

What is your first impression when mentioning algae? Is it the wild, endless blooming Algae, covering the surface of the entire pond? Indeed, Algae Bloom could impose numerous problems on the water management of private households, but what you might not have considered is the problem of red tide – a severe type of Harmful Algal Bloom (HAB) that paints the color of water red. The reason why Algae Bloom might grow out of control and develop into ‘red tides’ is multi-layered, and I am not going to dive into the scientific details here. But it is worth mentioning that changes in the normal functionality of the marine ecosystem, loss in biodiversity and water pollution are all significant causes of the trend of the rising number of HAB in the past few years.

The effect of harmful Algae Bloom can be detrimental both to marine organisms and to ourselves. Some toxins produced by certain species of algae during HAB can be fatal to fish, shellfish, mammals, and birds; for example, Scandinavian and South Pacific reef fish, as well as shell fishing along US coasts. As the toxins affect many species that humans consume, they could be distributed further up the food chain, causing symptoms of illness such as numbness, drowsiness, incoherent speech, and even as severe as respiratory paralysis. As the toxins accumulate in the shellfish we consume, more problems such as PSP, DSP, ASP, NSP could start to arise, and the toxins that cause them are highly temperature-resistant, which means simply cooking or boiling them at high temperature fails to protect us from relevant diseases. Apart from impact from toxin dispersion, it could also directly lead to the death of local species: during the process of decomposition, the algae sucks away oxygen in the water, leading to insufficient levels of oxygen for animals within the same habitat. Those species most heavily affected include shell organisms and shrimp.

Growing HAB cases

As the speed of economic development accelerates throughout the globe, many potential causes of HAB are being enhanced, such as changes in salinity, temperature, solar illumination of water, decrease in biodiversity, increase in marine pollution, and changes in climate patterns such as tidal currents and hydrographic conditions. Researchers have suggested that as global warming emerges, the thermal expansion of water could cause a rise of sea level in 2100 by 0.1-0.9 meters compared to 1990, and as Photosynthesis is the basic process within the marine ecosystem, both rates are very likely to double when temperature increases by 10°.

The severity and frequency of HAB have increased year on year. Taking China as an example, a recent analysis of the change in bloom frequency and duration in Taihu shows that prior to 1997, HAB occurrence only lasted about a month. However, since then, bloom duration has increased to be almost year-round. Additionally, the initial date when blooms first occur during the year has become earlier and earlier. A 10-year record of images of Yellow Sea region in China have shown that prior to 2007, the area covered by HAB cases was <21 km squared, while in 2008 the scale of the bloom was >1900 km squared, and in 2009 it was 1600 km squared. The HAB incident that occurred in 2008 during the Olympics led to significant economic loss and was highly disruptive, as well as bringing more attention from both public and private space to this issue.

Narrowing the scope down to local areas in Hong Kong, from 1975 to 2020 there had been a total of 964 HAB cases, with 28 of them involving the death of fish. The number peaked in 1988, with a staggering 88 cases in that year alone, but has fallen to around 10-20 cases per year recently due to improved public and private sector awareness of the issue and more effective regulations.

Friend or Foe? Potential “Algae Solutions”

Reading about all the detrimental effects and rising cases of HAB might make you worry about how we should go about solving this deteriorating global problem. Nevertheless, by exploring the potentials of using algae and microalgae in processes such as wastewater recycling, biodiesel, biofuel production and even electricity production, we have the potential to turn this around.

The first use-case that I would like to elaborate on is Micro-algae for Waste Water Treatment (WWT) . The rationale behind it is such that microalgae and algae-based water treatment technologies in general are very efficient in fixing inorganic N and P. Currently, the use of microalgae in WWT mainly focuses on two broad aims - improving purification, or directly transforming contaminated water content. However, their significant potential lies in the flexibility of how they perform metabolic activities. They are capable of treating a wide variety of different sources of wastewater, as some of them carry out photoautotrophic metabolism and some use mixotrophic or heterotrophic metabolism.

Pilot experiments conducted in Hong Kong Shek Wu Hui STW have provided significant evidence that the removal rate of waste such as Ammonial-Nitrogen by algae could reach as high as 88%, a very effective solution in comparison to current methodologies. Numerous research have shown that the use of micro-algae in wastewater treatment is “a cost effective and feasible method for bio-fixation of CO2” (Almomani et al., 2019) thanks to their ability to utilize organic and inorganic carbon as well as inorganic N and P in wastewater for their growth, resulting in reductions in the concentration of these substances in the water.

Additionally, using microalgae for water treatment has a positive “side-effect” - the oxygen it generates during the process of metabolic activities. KOTO factory in Slovenia carried out a full-scale test for algae WWT solution, which involved mixing the algae with bacteria, where it absorbs carbon dioxide and turns it into oxygen. The result was an impressive 50-70% saving on energy used in wastewater treatment, and this has promoted the installation of such methods in more factories in Europe.

Further advantages of using algal culture in WWT include the fact that treatment can be done in absence of need for transition processes during N and P removal, which provide enormous economic and environmental incentives for the adoption of this method.

Nevertheless, to generalize and promote the integration of algae solutions into our economy, we need to propose an industrial production line, which brings together the research, engineering, application, market values actualization and business values maximization. This roadmap of industrialization could provide a guideline for industries to position themselves and engage in such green market processes.

Image Source: Prof. KC Ho’s PowerPoint

Furthermore, in the architecture field, we have also seen many innovative ideas being explored in recent years, leading to the development of such term - “Algaetecture”. Back in 2015, at Expo Milano 2015, the Urban Algae Canopy, developed by Hortus ecoLogicStudio, was showcased as a prototype of “the first bio-digital covering in the world that integrates in an architectural system cultures of micro-algae and digital protocols of cultivation”. The architecture used a façade and a roof composed of Micro-algae and was said to absorb carbon dioxide and produce oxygen at a rate of up to 10 times more efficiently than large trees. Another interesting architecture is the SolarLeaf project – “the world’s first bio-reactive façade that generates renewable energy from algal biomass and solar thermal heat.” This architecture allowed for flexibility in power and heat generation, with excess energy able to be stored with virtually no energy loss. Built in 2013, it converts light to biomass and heat using microalgae from the River Elbe nearby, and uses it to make the “bio-skin” for the building. As microalgae is a simple unicellular structure, it could reproduce at a rapid pace and could soon cover the bio-skin sections of the building. After two years of operation, the performance of the system was evaluated: the combined output of heat and biomass is 26,165 kWh per annually, with 13,471 kWh of electricity gain. We can see how this building fits perfectly alongside the concept of the circular economy, providing self-sufficient energy and at the same time, producing excess energy to be stored for future use or to fulfil insufficient supply in other sectors of the economy. Successful implementation of it will open a brand-new landscape for the integration of algae solutions into architectural space.

Image Source: © Brown Bird Design

Algae for a Green Economy

Algae is the new green growth industry; it perfectly demonstrates the beauty of nature and nature’s ability to provide solutions to problems. While recognizing the danger of Harmful Algae Bloom and trying to reduce its occurrence by improving water area regulation and public awareness, we could also utilize the unique characteristics of algae to bring new solutions to energy generation, greenhouse gases reduction and much more. The crucial step is to develop a comprehensive system and follow a structured approach when integrating algae solutions. We look forward to a future economy in which human activities become self-sufficient, moving towards a cleaner and more sustainable circulatory system.


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