Ricerc@Sapienza

Extensive and improper utilization of water from industrial, municipal, and agricultural activities generate 380 trillion L/y of wastewater worldwide. Wastewaters from different sources contain enormous amounts of nutrients such as carbon, nitrogen, and phosphorus. Thus, the recovery of these nutrients via appropriate sustainable process becomes a necessity. Among various processes microalgae-based technologies has attracted considerable attention and its strategies for sustainable and low-cost treatment of wastewater has allowed removal of over 70% nutrient loads from the wastewater.

In this research Scenedesmus obliquus and Chlorella vulgaris growth was tested on digestate sludge obtained from the anaerobic co-digestion treatment of the organic fraction of municipal solid waste (OFMSW) together with waste activated sludge (WAS). Digestate was diluted 1:10 and tested in three batch experimental conditions: with no pre-treatments (noPT), after centrifugation (AC) and after filtration (AUF), in order to evaluate microalgae limiting growth factors. The best growth was obtained by C. vulgaris on digestate AC compared to S.

Olive mill wastewater (OMW) was supplied to Scenedesmus sp. cultures to simultaneously achieve biomass production and wastewater biodegradation. Two OMW supply strategies were implemented to prevent the reduced growth performances that are attained, compared to photoautotrophic cultivation, when OMW is supplied at the beginning of cultivation (batch strategy). A fed-batch strategy including the gradual OMW supply yielded a biomass production equal to 0.86 g/L, while 1.4 g/L was attained by a two-stage strategy including OMW addition during nitrogen-starvation.

BACKGROUND: Mixotrophic and heterotrophic growth of microalgae through biodegradation of olive mill wastewaters (OMW) is a promising strategy to improve the economic viability of microalgae production processes. However, OMW are characterized by an elevated phenols content, which makes their treatment by biological processes difficult. In this work, the influence of OMW phenols on microalgae growth was investigated by using the phenols extracted with a resin from OMW.

Olive mill wastewater (OMW) utilization for microalgae cultivation has been investigated in different studies, in which it is generally strongly pre-treated before use. Here a common pre-treatment method (active carbon) has been carried out for OMW, and its influence on Tetradesmus obliquus growth (generally known as Scenedesmus obliquus) and phenol and sugar removal has been compared with untreated OMW. Before to carry out test on OMW, nitrate concentration in the media was optimized, finding a modified BG11 media more adequate for our experimental aims. T.

Microalgal productivity under changing conditions of light intensity and temperature is a crucial parameter for evaluating profitability and sustainability of an outdoor cultivation in cylindrical photobioreactors. The control of the principal outdoor variables, even for the more accurate systems, is subject to a wide number of factors that might influence the measures taken, thus falsifying their correlation with the microalgal growth.

The influence of Ca2+ concentration on the growth of the microalga Scenedesmus sp. in heterotrophic and photoautotrophic cultivations was investigated. Heterotrophic growth was induced by the addition of olive mill wastewaters (9% v·v-1) to the culture. Variations in the calcium concentration affected differently biomass production depending on whether microalgae were cultivated under heterotrophic or photoautotrophic regime. In photoautotrophic regime, increasing the calcium concentration from 20 to 230mgL-1 decreased maximum cell concentration and growth rate.

Biotechnologic processes based on microalgae cultivations have had an increasing interest from the early 2000s. Microalgae are microorganisms able to produce and accumulate a large variety of industrially relevant compounds starting from renewable and cheap resources. However, 3–10 € per kg of dry biomass is the minimum cost for microalgae biomass production that has been estimated by different studies published in 2016. This high cost restricts industrial applications only to the production of high-value products.

Microalgae are a promising feedstock for the future of the industrial chemistry. Among microalgae, Tetradesmus obliquus (generally known as Scenedesmus obliquus) is one of the most studied species due to its robustness and its good performances for production of lipids, proteins and carbohydrates. However, the high production costs still limit large part of the possible applications. The exploitation of the heterotrophic metabolism for microalgae cultivation may potentially improve the biomass production sustainability, especially if organic substrates are obtained from wastewaters.