Uses of the reject brine from inland desalination for fish farming,Spirulina cultivation, and irrigation of forage shrub and crops

This paper offers a review on different experiences that have been conducted in South America, which are of interest for the agricultural use of the brine reject originated in inland desalination plants. The results obtained by a combined production scheme that uses brine reject from inland desalination plants for fish farming and for the irrigation of halophyte forage shrubs are summarized. This scheme has succeeded in turning an environmental problem (the brine reject disposal in inland areas) into a source of new economical activities. However, despite a slightly salt removal capacity shown by the halophytes, this production scheme was not able to prevent a progressive salinization of the land irrigated with the reject brine. The yields obtained are analyzed in terms of fish and forage production as well as the weight gain in the livestock fed with the halophytes. Also, due to its characteristics and good performance in arid regions and saline waters, the cultivation of Spirulina cyanobacteria is proposed as an alternative for fish farming within this production scheme. Finally, a series of South American studies addressing the irrigation of crops under saline conditions are reviewed, with the objective of establishing their potential use for reject brine management. © 2015 Elsevier B.V. All rights reserved.

A. nummularia offered forage yields of 5.5–8.5 ton·ha− 1·year−1 when irrigated with the brine reject, which is a far greater value than that obtained in other arid parts of South America, where it is cultivated as a wild crop. Previously to the irrigation of the Atriplex fields, the brine reject was used for the growing of tilapia (with a yearly yield of 648– 589 kg for a 330 m3 pond) and then enriched with manure and organic waste. The forage obtained with Atriplex made a positive contribution in the support of the local herd. For goat feeding, it was stated a convenient rate of participation of between 38.3% and 64.6% in the diet. Besides the environmental benefits, the integrated scheme used in the Semi Arid region of Brazil, which produces fish plus forage saltbush, revealed to be a nice example of how to add value to a waste stream with potential pollution effects. Also, value is added to the surface occupied by evaporation ponds as well as to unproductive soils in the surroundings of the desalination plant. Thus, by inserting activities such as aquaculture of tilapia species or cultivation of Spirulina inside the production scheme, new products and byproducts are created enhancing the overall value chain. In addition to fresh drinkable water, the local communities of these arid regions get benefited with the production of forage from Atriplex saltbush, oil from fish processing or Spirulina, all of them excellent nutritional complements for local livestock. The most valuable products of this production scheme are filleted frozen fish and hay for the feeding of goats. The production of collagen as a byproduct of tilapia processing and the use of halophyte plants and algae for biofuel production are also interesting alternatives and deserve further studies. In this production scheme, the cultivation of Atriplex is proposed as the last stage in the use of the brine stream. These species have a good capacity of absorbing salt and protecting the soil. However, an eventual drainage of the soil may be necessary. When considering the irrigation of halophyte plants, the drainage fraction associated Table 6 Yield reduction (inhibition of the growth) of different crops irrigated with saline waters in the Semi Arid region of Brazil and in Venezuela and Colombia. Species Type of cultivation Range of salinity of the study (mS·cm−1) Inhibition of the growth for each increasing mS·cm−1 within the range Source Lettuce (Lactuca sativa) Beetroot (Beta vulgaris) Tomato (Lycopersicon esculentum) Tomato (Lycopersicon esculentum) — Miller Astona variety Sunflower (Helianthus annuus L.) Sunflower (Helianthus annuus L.) Sunflower (Helianthus annuus L.) — Red Sun variety Cotton (Gossypium hirsutum) Cotton (Gossypium hirsutum) Papaya (Carica papaya L.) Feijoa (Acca sellowiana) Sugar cane (Saccharum officinarum) — My 5514 variety Hydroponic Hydroponic Hydroponic Soil cultivation Soil cultivation Soil cultivation, under nitrogen fertilization Hydroponic Soil cultivation Soil cultivation, under nitrogen fertilization Soil cultivation Soil cultivation Soil cultivation 1.3–5.2 1.2–5.2 2.1–10.1 1.8–8.8 0.5–5.0 0.5–4.9 0.5–16.4 0.5–8.5 0.7–8.7 1.2–4.8 2.8–11.1 3.2–6.0 7.0%, 15.0%, 17.0% 7.0% to 9.0% 2.6% 6.0% 10.0% to 11.0% 7.6% 5.8% 10.0% 9.5% 7.2% 20.0% 10.0% [84–86]