A Sustainable Method of Production Towards Food Security Using Aquaponics: A Case Study from Oman

In order to achieve Sustainable Development Goal (SDG) 12, Gulf countries need to look for innovative and sustainable production of food for local and expatriate populations. Opportunity exists for method of food production using limited but highly treated wastewater. A change to fish and vegetable production using treated wastewater will contribute to sustainable consumption and production (SCP) in the region. Therefore, the objective of the study conducted at Sultan Qaboos University, Oman was to evaluate the effect of tertiary treated wastewater on fish growth and later on the effect of the produced effluent coming from fish tank on grown crops. Nine tanks with dimensions of 80×40×40 cm were filled either with freshwater or a mixture of freshwater and treated wastewater (at 50:50 and 75:25 ratios). Each tank was stocked with 25 tilapias (Oreochromis niloticus) with an initial body weight of 49 g. Each tank was connected to another tank of same dimensions that was used to grow lettuce and bean crops on the top layer. Water was circulating between the two tanks. No fertilizer was added to all treatments and all tanks got similar amount of fish feed. It was found that tanks with treated wastewater got higher concentrations of dissolved oxygen due to algae growth and more salts content due to minerals added from treated wastewater compared to fresh water alone. Therefore, lettuce and bean growth was much better and got higher values of chlorophyll content compared to plants in control tanks. For heavy metal analysis, all waters got similar values but, in some samples, the concentrations of B, Cu, Mn and Zn were higher in treated wastewater compared to fresh water and that was reflected in lettuce roots. For the edible part, lettuce grown in treated wastewater got higher value of Fe and B compared to control. Similar concentrations were found with bean plants with higher values in treated wastewater compared to freshwater. However, low concentrations of heavy metals were found in the edible parts of all plants in all treatments. Fish analyses showed that all tested heavy metals were within the safe limit. The positive aspect of this system is that it will help the environment by utilizing treated wastewater and reducing fertilizer applications. Moreover, farmer income will increase since both fish and crops will be produced with minimum resources.