Wastewater contains nutrients that must be managed carefully, but it can also be viewed as a source of recoverable resources. Microalgae offer an interesting connection between these two perspectives: they can grow in nutrient-rich wastewater, producing biomass that may have further uses after cultivation. One possibility is its use as a biofertilizer.
A recently published study in the Journal of Applied Phycology examines this possibility through a case study of the Bojongsoang Wastewater Treatment Plant in Indonesia. The authors assess the environmental performance of producing microalgae-based biofertilizer from wastewater, placing the proposed pathway within the broader discussion around chemical fertilizer use, greenhouse gas emissions, and nutrient pollution.
Rather than considering microalgal biomass as an isolated product, the research applies consequential life cycle assessment. This approach directs attention to the environmental changes that could follow from a production decision, including effects elsewhere in the systems connected to it. For emerging circular processes, this wider perspective can reveal trade-offs that may be missed when attention is limited to the immediate production stage.
Context-specific analysis
The Bojongsoang case also shows why local conditions matter. Wastewater composition, treatment infrastructure, energy requirements, biomass processing, and the products that a biofertilizer might replace can all influence an environmental assessment. The study therefore contributes a context-specific analysis rather than suggesting that wastewater-grown microalgae will produce the same outcomes in every location.
This work will be relevant to researchers studying applied phycology, resource recovery, wastewater treatment, life cycle assessment, biofertilizers, and circular approaches to agriculture. It also illustrates how environmental evaluation can be incorporated while a promising use for microalgal biomass is still being investigated, before its benefits are assumed or generalized.