Expanded algal cultivation can reverse key planetary boundary transgressions

Abstract

Humanity is degrading multiple ecosystem services, potentially irreversibly. Two of the most important human impacts are excess agricultural nutrient loading in our fresh and estuarine waters and excess carbon dioxide in our oceans and atmosphere. Large-scale global intervention is required to slow, halt, and eventually reverse these stresses. Cultivating attached polyculture algae within controlled open-field photobioreactors is a practical technique for exploiting the ubiquity and high primary productivity of algae to capture and recycle the pollutants driving humanity into unsafe regimes of biogeochemical cycling, ocean acidification, and global warming. Expanded globally and appropriately distributed, algal cultivation is capable of removing excess nutrients from global environments, while additionally sequestering appreciable excess carbon. While obviously a major capital and operational investment, such a project is comparable in magnitude to the construction and maintenance of the global road transportation network. Beyond direct amelioration of critical threats, expanded algal cultivation would produce a major new commodity flow of biomass, potentially useful either as a valuable organic commodity itself, or used to reduce the scale of the problem by improving soils, slowing or reversing the loss of arable land. A 100 year project to expand algal cultivation to completely recycle excess global agricultural N and P would, when fully operational, require gross global expenses no greater than $2.3 × 1012 yr−1, (3.0% of the 2016 global domestic product) and less than 1.9 × 107 ha (4.7 × 107 ac), 0.38% of the land area used globally to grow food. The biomass generated embodies renewable energy equivalent to 2.8% of global primary energy production.

Carbon limitation in hypereutrophic, periphytic algal wastewater treatment systems

“…Technologies that implement natural processes, such as algal wastewater treatment floways, to reverse the effects of anthropogenic influence on the environment stand to lead the way in natural resource management and remediation. The widespread adoption of algal treatment technologies may help solve the growing global challenge of nutrient runoff and its resulting eutrophication of our fresh and estuarine ecosystems [62].…”

Cultivation of algal biofilm and mat communities from the Garhwal Himalayas for possible use in diverse biotechnological applications

“…The selection of substratum is a very important component for getting quick initial development and ensuring enhanced biomass production of biofilm and mat communities. The nature of the substratum can affect the initial adhesion strength of algal cells and the composition of the algal community [ [35] , [36] , [37] , [38] , [39] , [40] , [41] ]. In the present study, different materials were tested for their suitability to act as a substratum for the development of test biofilm and mat communities.…”

Vetiver and Dictyosphaerium sp. co-culture for the removal of nutrients and ecological inactivation of pathogens in swine wastewater

“…Water scarcity is expected to become more widespread in the coming years, and eliminating wastewater discharges is critical for water preservation [24]. As one of the most cost-effective and beneficial uses for algal biomass is returning it to local land [25], ecologically-remediated wastewater could be utilized as both irrigation water and soil amendment, thus eliminating wastewater discharge. The present study aimed to develop a plant-microalgal co-culture strategy for increasing the suitability of plants and microalgae for use in engineered wastewater treatment systems.…”