Removal of phosphate by the green seaweed Ulva lactuca in a small-scale sewage treatment plant (Ios Island, Aegean Sea, Greece)

Abstract

In the present study, the use of seaweeds for phosphate absorption was examined as a tertiary treatment in sewage treatment plants, to improve the water quality and reduce eutrophication risks. The data came from both laboratory and field experiments that took place on Ios Island sewage treatment plant. Three different macroalgae were tested and Ulva lactuca was finally chosen thanks to its high survivability in low salinity waters. Since the main restrictive factor was low salinity, we initially established the ratio of seawater:effluent that combined satisfactory viability with maximum phosphate absorption. The biomass growth under these conditions was also examined. Based on the above results, we designed a continuous-flow system with a 1/4 volume per hour water turnover, in a mixture of 60% sewage effluent: 40% sea water and 30 g L -1 initial biomass of U. lactuca that must be renewed every 10 days. Under these conditions and time frame, the phosphate content of the effluent was reduced by about 50%.

Growth, protein and carbohydrate contents in Ulva rigida and Gracilaria bursa-pastoris integrated with an offshore fish farm

“…Ulva and Gracilaria are attractive model species for intensive culture due to their high growth yields and bioremediation efficiencies Zhou et al 2006;Barrington et al 2009;Tsagkamilis et al 2009). Furthermore, both macroalgae have established commercial markets, such as agar, food for humans, and fodder for fish and abalone, and they might fit as potential feedstock for bioethanol production Yanagisawa et al 2011), pending further research.…”

Uptake kinetics and storage capacity of dissolved inorganic phosphorus and corresponding N:P dynamics in Ulva lactuca (Chlorophyta)

“…, Tsagkamilis et al. ). The majority of studies related to the efficiency of N and P removal from seawater by U. lactuca have been conducted under field conditions (Neori et al.…”

“…For example, Tsagkamilis et al. () indicated finding an optimal combination of biomass and water flow rates for satisfactory nutrient uptake by U. lactuca , by measuring DIP removal from the effluent in a small‐scale water treatment facility. Quantification of DIP uptake kinetics over time, however, and the saturating storage capacity of DIP in U. lactuca have not yet been studied.…”

UK Macro-Algae Biofuels: A Strategic Management Review and Future Research Agenda

“…Additionally, the majority of biomass comes from a relatively small number of species in the orders Laminariales and Fucales with subtidal large brown kelps of the order Laminariales thought to have the most potential [39]. Particular species that have been suggested for biofuel production and have been successfully grown and harvested include Gelidium amansii, Laminaria japonica, Laminaria saccharina, Sargassum fulvellum, Sargassum naozhouense, Saccharina latissimi, Palmaria palmata, Ulva lactuca and Ulva pertusa amongst others [15,39,40]. Some of the earliest investigations were conducted as part of the US Ocean Food and Energy Farm project [41] and the Marine Biomass Program [42].…”

“…One positive impact is that seaweed farming does not use fertilisers and there is also some research to suggest that macro-algae can clean waters by purifying polluted water by the removal of nutrients [40,78] avoiding eutrophication in seas and oceans [15]. It is also suggested that these characteristics do not interfere within its feasibility as a feedstock for biofuel production [79].…”