scholarly journals Anaerobic Mineralization of Recirculating Aquaculture Drum Screen Effluent for Use as a Naturally-Derived Nutrient Solution in Hydroponic Cropping Systems

Conservation ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 151-167
Author(s):  
Joseph Tetreault ◽  
Rachel Fogle ◽  
Todd Guerdat

Operation and effluent treatment costs are limiting factors for the success of recirculating aquaculture systems (RAS) in meeting seafood demand in the United States. Adopting a capture-and-reuse waste management model similar to terrestrial agriculture farmers would allow RAS farmers to monetize effluent and offset production costs. The moisture content and nutrient profile of RAS effluent makes it a potential option for use as a hydroponic fertilizer. Treatment of RAS waste is needed to mineralize particulate-bound nutrients before becoming a viable hydroponic nutrient solution. Anaerobic treatment (AT), a method used by municipal and agricultural waste treatment facilities to reduce total solids, has been shown to successfully mineralize particulate-bound nutrients from RAS effluent. Continuously mixed anaerobic batch bioreactors were used to evaluate the degree to which AT may mineralize particulate-bound nutrients in solid RAS waste. Concentrations of twelve different macro- and micro-nutrients were analyzed in the waste before and after treatment. Effluent samples were analyzed to determine the fraction of each nutrient in the solid and aqueous forms. This study showed that AT is an effective method to mineralize particulate-bound nutrients in RAS effluent and the mineralization rate data may be used to design a pilot-scaled flow-through RAS effluent treatment system.

Horticulturae ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 334
Author(s):  
Joseph Tetreault ◽  
Rachel Fogle ◽  
Todd Guerdat

Controlled environment agriculture (CEA) technologies are required to meet current and future food production demand as the global population rises, arable land decreases, and minerals for fertilizer production are depleted. Hydroponics and recirculating aquaculture systems (RAS) are intensive production methods that can provide season-independent vegetables and seafood in urban settings but are limited by a reliance on fertilizing solutions made from finite mineral reserves and the treatment and disposal costs of nutrient rich effluent, respectively. The development of a capture and reuse system where RAS effluent is solubilized to become plant-available and utilized as a hydroponic nutrient solution would aid both industries and increase food security in urban food deserts. Aerobic mineralization is used in domestic wastewater treatment to reduce solid content and solubilize particulate-bound nutrients. Preliminary studies have also shown that aerobic mineralization can be an effective method for RAS effluent treatment. Aerobic batch reactors were used to mineralize RAS effluent in this study. Suspended solids reduction achieved in the reactors was measured throughout the experiment and the plant-availability of twelve nutrients was determined before and after treatment. It was shown that aerobic mineralization can effectively reduce particulate-bound solids and solubilize nutrients to increase plant utilization in RAS effluent.


Author(s):  
Peter Scott

From an international perspective, the inter-war car industry was a British success story. Britain ranked only second to the United States as the world’s leading producer of, and market for, automobiles, owing to a relatively strong domestic market by European standards. However, while consumers’ expenditure was high, it was not deep—car ownership per capita in 1938 being around a third of US levels. This chapter examines why the British automobile sector failed to take off into mass market diffusion. A number of important factors are highlighted, including lower British wages relative to the United States; punitive vehicle and petrol taxation; and the high unit production costs incurred in serving a market too small to justify Fordist mass production. However, a more fundamental reason was the low priority given to car ownership in a relatively small, densely populated, and highly urbanized island nation with well-developed public transport networks.


2015 ◽  
Vol 65 ◽  
pp. 17-26 ◽  
Author(s):  
Paulo Fernandes ◽  
Lars-Flemming Pedersen ◽  
Per Bovbjerg Pedersen

2021 ◽  
Vol 21 (7) ◽  
pp. 3975-3979
Author(s):  
Min-Jin Hwang ◽  
Jeongmin Cha ◽  
Eun-Sik Kim

In a fish farm, the water quality is important to ensure fish growth and farm productivity. However, the study of the quality of water using in aquaculture has been ignored until now. Although there are several methods to treat water, nanomaterials have not yet been applied for indoor fish farming because it may difficult to supply a sufficient amount of water, and the operating parameters have not been developed for recirculating aquaculture systems. Nanotechnology can be applied to treat water, specifically through adsorption and filtration, to produce drinking water from surface water and to treat wastewater by processing a high volume of effluent. The adsorption and filtration of seawater has also progressed to allow for desalination of seawater, and this is recognized as a necessary tool for extended treatment protocols of various types of seawater. This study investigated the treatment of aquaculture water using nano-porous adsorbents (e.g., pumice stone) to control the contaminants in seawater in order to maintain the water quality required for aquaculture. The results are used to derive an analytical relationship between the ionic species in aquaculture water, and this provides empirical parameters for a batch reactor for aquaculture. The quality of the influent and effluent for aquaculture is compared using time-series analyses to evaluate the reduction rate of ionic components and thus suggest the optimum condition for fish farming using bioreactor processes.


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