Comparative life cycle assessment of conventional and novel microalgae production systems and environmental impact mitigation in urban-industrial symbiosis.

The versatility of microalgae biomass as candidates for various products and bioremediation needs motivates interests towards design and implementation of novel microalgae bioreactors. Conventional open-reactors are reliant on large quantities of sunlight and space while yields are constrained by outdoor environment conditions. Conversely, closed-reactor systems like bubble columns reduces these constrains on microalgae growth while occupying far less space at the expense of high energy demands, notably from lighting systems. A novel patented closed reactor design has recently been proposed that improves the bubble column concept with an efficient and effective lighting system. The present study uses Life Cycle Assessment approach to compare the environmental performance of conventional reactors and the proposed internally luminated novel closed reactor design, expressing impacts per kg biostimulant for the Scenedesmus almeriensis harvest from such units. All performance data was collected from a pilot facility in Almeria, Spain. Urban-industrial symbiosis scenarios are also portrayed in the study using wastewater and incinerator flue gas. Results show that under synthetic nutrient and carbon inputs in Spanish pilot operations, the cumulative energy demand for the novel photobioreactors is similar to conventional vertically-stacked horizon bioreactors but are substantially more demanding than conventional open reactors. However, when leveraging renewable energy sources and the photosynthesis process to consume wastestreams in urban-industrial symbiosis scenarios, the novel photobioreactor was able to achieve up to 80 % improvements in several impact categories e.g. eutrophication and climate change. Impact mitigation credits per kg dwt biomass across all energy scenarios in symbiosis amount to ≈1.8 kg CO2eq and ≈0.09 kg PO4 eq. This highlights that such closed and internally illuminated photobioreactors can be competitive with conventional reactors, and have potential to harness photosynthesis to reduce environmental burdens in an urban-industrial symbiosis setting. Possible economies of scale and the associated potential gains in efficiencies are further discussed.

OPTIMIZATION OF A NEW CULTURE MEDIUM FOR THE LARGE-SCALE PRODUCTION OF PROTEIN-RICH ARTHROSPIRA PLATENSIS (OSCILLATORIALES, CYANOPHYCEAE).

Our aim was to develop a novel medium for the large-scale production of protein-rich Arthrospira with potential applications as a biofertilizer. The novel culture medium, termed as FM-II, was formulated using low-cost commercial chemicals and specifically designed to improve protein production. Both Arthrospira platensis and Arthrospira maxima were produced using FM-II and Arnon medium, which was used as a control. Photosynthetic status of the cells, which was checked by measuring chlorophyll fluorescence, biomass dry weight and protein content, was assessed daily. Arthrospira platensis had higher biomass and protein productivities than A. maxima when cultured in both control and FM-II media. Incorporation of varied micronutrients into FM-II formulation did not improve biomass productivity. Maximum biomass dry weight in FM-II and control medium was 2.9 and 2.5 g · L-1 , respectively. Total protein content of the biomass ranged between 55% and 65%, suggesting potential for being used in the development of high-value agricultural products. As some nutrients were discarded unused, the initial content of phosphates and bicarbonates was reduced by 75% and 50%, respectively, without affecting the process productivity. Results reported herein could promote the production and utilization of Arthrospira platensis by significantly reducing productions costs and therefore increasing the feasibility of the process.

Life cycle assessment of high rate algal ponds for wastewater treatment and resource recovery.

The aim of this study was to assess the potential environmental impacts associated with high rate algal ponds (HRAP) systems for wastewater treatment and resource recovery in small communities. To this aim, a Life Cycle Assessment (LCA) was carried out evaluating two alternatives: i) a HRAP system for wastewater treatment where microalgal biomass is valorized for energy recovery (biogas production); ii) a HRAP system for wastewater treatment where microalgal biomass is reused for nutrients recovery (biofertilizer production). Additionally, both alternatives were compared to a typical small-sized activated sludge system. An economic assessment was also performed. The results showed that HRAP system coupled with biogas production appeared to be more environmentally friendly than HRAP system coupled with biofertilizer production in the climate change, ozone layer depletion, photochemical oxidant formation, and fossil depletion impact categories. Different climatic conditions have strongly influenced the results obtained in the eutrophication and metal depletion impact categories. In fact, the HRAP system located where warm temperatures and high solar radiation are predominant (HRAP system coupled with biofertilizer production) showed lower impact in those categories. Additionally, the characteristics (e.g. nutrients and heavy metals concentration) of microalgal biomass recovered from wastewater appeared to be crucial when assessing the potential environmental impacts in the terrestrial acidification, particulate matter formation and toxicity impact categories. In terms of costs, HRAP systems seemed to be more economically feasible when combined with biofertilizer production instead of biogas. On the whole, implementing HRAPs instead of activated sludge systems might increase sustainability and cost-effectiveness of wastewater treatment in small communities, especially if implemented in warm climate regions and coupled with biofertilizer production.

Modeling of photosynthesis and respiration rate for Isochrysis galbana (T-Iso) and its influence on the production of this strain.

Isochrysis galbana is a widely-used strain in aquaculture in spite of its low productivity. To maximize the productivity of processes based on this microalgae strain, we have developed a model considering the influence of irradiance, temperature, pH and dissolved oxygen concentration on the photosynthesis and respiration rate. Results demonstrate that this strain tolerates temperatures up to 35 °C but it is highly sensitive to irradiances higher than 500 µE m(-2)s(-1) and dissolved oxygen concentrations higher than 11 mgl(-1). We have validated the developed model using data from an industrial-scale outdoor tubular photobioreactor demonstrating that inadequate temperature and dissolved oxygen concentrations reduce productivity to half that which is maximal, according to light availability under real outdoor conditions. The developed model is a useful tool for managing working processes, but especially in the development of new processes based on this strain and to take decisions regarding optimal control strategies.

Construção e uso de indicadores para avaliação do manejo da ordenha: uma proposta metodológica participativa / Construction and use of indicators to assess milking management: a participatory methodology proposal

O objetivo deste trabalho foi adaptar e testar uma metodologia participativa para promover e avaliar as mudanças de percepção e de atitude dos agricultores com relação às práticas de manejo sanitário da ordenha, através da construção e uso de indicadores que permitissem aos agricultores um processo de ação-avaliação constante. Foi realizado um estudo de caso em quatro Unidades de Produção Familiar (UPF), no município de Guaraciaba (SC), envolvidas na atividade leiteira. Após a caracterização das UPF e diagnóstico sanitário do rebanho, foi feita a construção participativa de indicadores de manejo sanitário de ordenha, a qual foi utilizada pelos agricultores ao longo de três meses para avaliação de suas práticas de manejo. Ao final desse período, foram realizadas entrevistas com as famílias participantes para apreender a sua percepção a respeito da metodologia empregada. Os agricultores avaliaram positivamente o uso da metodologia, destacando a melhoria de vários indicadores, devido às mudanças de atitudes. Destacaram também que a eficiência da metodologia se deve ao fato de ela proporcionar uma reflexão sobre aspectos reais da vida dos agricultores. Assim, a proposta metodológica participativa utilizada neste trabalho, dentro de uma perspectiva emancipadora, mostrou-se uma importante ferramenta de avaliação de sistemas, coerente com as premissas da Política Nacional de Assistência Técnica e Extensão Rural - PNATER.

The aim of this study was to adapt and test a participatory methodology to promote and assess changes in perception and attitude of farmers regarding management sanitary milking practices, through the construction and use of indicators that may allow farmers a constant process of self-evaluation. We conducted a case study in four Family Farms (UPF), in the municipality of Guaraciaba (SC) involved in the dairy business. First a characterization of the UPF and diagnosis of herd health were carried out. The second step was the construction of participatory indicators for sanitary milking management, which were used by farmers over three months for evaluation of their management practices. After this period participating families were interviewed with to grasp their perceptions towards the methodology employed. Farmers gave a positive assessment of the use of the methodology, highlighting the improvement of various indicators due to changes in attitudes promoted by the use of the methodology. They also highlighted that the efficiency of the method is due to the fact that it can provide a reflection on real aspects of the farmers' life. Thus, the participatory methodology used in this study within an emancipatory perspective, proved to be an important tool for evaluating systems, consistent with the assumptions referred in the National Technical Assistance and Rural Extension - PNATER.