Few microbial studies in aquaponics, a growing trend in food production, have been conducted to determine food safety status. The aim of this study was to determine the food safety status and the effectiveness of ultraviolet treatment (15 W, luminous flux of 900 lm) as a food safety intervention in reducing the microbial loads of the water system in a model aquaponic unit growing lettuce, basil, and barramundi (Australian Sea Bass). Sweet basil, bibb lettuce, water samples, and fish swabs were collected throughout the 118-day production period, and microbial analysis was conducted in triplicate for the presence of E. coli O157:H7, Salmonella spp., and the prevalence of aerobic plate counts (APC), coliforms, and fecal coliforms in these systems. Absence of foodborne pathogens was confirmed using ELISA technology and enumeration through petrifilms (coliform/E. coli). A significant increase was observed in aerobic plate counts over the trial period (1 to 3 log 10 CFU·mL −1 ) in the presence and absence of UV (p > 0.05). Ultraviolet treatment did not significantly reduce the APC or coliform counts when compared to the control system samples. Future work should focus on improving the unit design, the evaluation of bio-solid filtration, and other food safety interventions.

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Aquaponics is an agricultural practice incorporating aquaculture and hydroponic principles. This study assesses the current system design and production practices of the aquaponic industry, compares these metrics by stakeholder group, identifies trends, and provides recommendations for future development. An electronic survey of aquaponic stakeholders was conducted from December 2019 to June 2020 targeting hobbyists, producers, and educators from various aquaponic-focused professional associations, email and social media groups. Of 378 total responses, 84% came from the United States and were clustered in plant hardiness zones five to nine. Aquaponic systems were commonly homemade/do-it-yourself (DIY), many of which incorporated commercially available (turn-key) technology. Most growers used coupled systems that integrated recirculating aquaculture systems and either deep-water culture (DWC) or media bed hydroponic units. Common plant lighting sources were sunlight and light emitting diode (LED). Water sources were typically municipal or wells. Personal labor input was typically less than 20 hrs/wk. Funding sources were primarily personal funds, followed by government grants, and private investor funds. System sizes varied greatly, but the median area was 50 to 500 ft2 for hobbyists and educators and 500 to 3,000 ft2 for producers. Respondents commonly sold vegetable produce, training and education, food fish, and microgreens. Tilapia and ornamental fish were commonly grown, with 16 other species reported. Common crops were lettuce, leafy greens, basil, tomatoes, peppers, and herbs with many additional lesser-grown crops reported, including cannabis. Overall, the industry still growing, with a large portion of stakeholders having less than two years of experience. However, veteran growers have remained in operation, particularly in the producer and educator groups. The survey results suggest a shift away from outdoor systems, media beds, tomatoes, ornamental fish, and perch production, and a shift toward decoupled systems, DWC, drip irrigation, and wicking beds, larger system area, leafy greens, and trout/salmon production compared to previous industry surveys. The reduced diversity of plant species grown suggest some level of crop standardization. Commercial producers tended to sell more types of products than other stakeholders, suggesting that diversification of offerings may be key to profitability. The combined production area specified by respondents indicates the industry has grown substantially in recent years. Finally, the presence of bank loan-funded operations suggests increased knowledge and comfort with aquaponics among lenders.

Raised bed production trials were conducted to evaluate the effectiveness of effluent from a biofloc-style recirculating aquaculture system producing nile tilapia (Oreochromis niloticus) as nutrient-rich irrigation water for fall ‘Celebrity’ tomato (Solanum lycopersicum) production. The objective of this study was to provide baseline vegetable production data and justification for using aquaculture effluent as a water and nutrient resource. The experiment was a split-plot, randomized block design with three treatments: aquaculture effluent, granular fertilizer, and fertigation. Tomato seeds were sown in June, transplanted in August, and grown until Oct. 2019 in nine replicated raised beds. Conventional field tomato production practices were followed throughout the trial, and data were collected for tomato fruit yield, market quality, size, leaf greenness (SPAD), and foliar nutrient analysis. Fruit yield was similar between fertigated and aquaculture effluent treatments, with granular fertilizer resulting in yield that was significantly lower (P ≤ 0.033). SPAD measurements were similar among treatments. All nutrients met or exceeded sufficiency ranges. Foliar nutrient analysis revealed no significant difference for nitrogen, phosphorus, potassium, magnesium, calcium, boron, zinc, manganese, and iron among treatments. Sulfur and copper levels were significantly lower (P < 0.05) with aquaculture effluent treatment as compared with the granular and fertigated treatments. Overall, tomato production using aquaculture effluent as a water and nutrient supplement produced similar yields to commercial practices, making it potentially viable for producers.

Introduction The design and development of steam-injection fields is a mature subject. Because the tubulars in these wells invariably experience inelastic loading, issues such as the effects of temperature on the static and cyclic (fatigue) material properties become important. The original papers that address steam-injection casing-design issues date back to the 1960s. These studies include temperature prediction (Leutwyler and Bigelow 1965), casing-stress analysis (Willhite and Dietrich 1967), and development of design guidelines (Holliday 1969). Though these works acknowledge the role of temperature on the static and cyclic material properties, data on the cyclic thermal properties of oil-country tubular-goods steels rarely appear in oilfield literature (Placido et al. 1997; Maruyama et al. 1990). This paper presents a mathematical model of casing strings subjected to thermal loads in steam-injection wells. The model includes the effects of temperature on material properties and the effects of wellbore curvature and prestress during the heating cycle. Several counterintuitive aspects of the casing-stress state during cooling/unloading are examined. Further, the general equations are shown, with appropriate simplifications, to reproduce the earlier work (Willhite and Dietrich 1967; Holliday 1969). Example calculations are used throughout to illustrate key insights.

This paper describes the material selection for tubing in water injection wells for deepwater applications. It details the qualification and deployment of an alternative to duplex corrosion resistant alloy (Duplex-CRA) tubing, including the testing work that was performed. Also described are the operational aspects of running the resulting product in several deepwater wells. With the advance into expensive subsea wells, along with the use of produced water re-injection and the historical performance of de-oxygenation systems, most recent water injector designs for deepwater projects do not utilize carbon steel materials. The common materials are Duplex-CRAs, which are often an order of magnitude higher in price than carbon steel, and carry a significantly longer delivery time. There are few alternatives to Duplex-CRAs. A common choice is glass reinforced epoxy (GRE) lined tubing, whose costs are similar in magnitude to carbon steel tubing and whose delivery time is significantly shorter. GRE-lined tubing requires a set of rings and/or flares to be inserted at the length to length interface. Initially, the connection was modified to allow insertion of the rings/flares in a machined groove in the coupling. This was acceptable for many applications. However, for deeper water, higher pressure wells connection with better performance was required. By employing a modified connection on GRE-lined tubing, BP successfully used it in shallower water injection wells. By 2003, the need was recognized for GRE application in deepwater injection wells. This would require qualification for the following further requirementsDeep water tubing generally requires un-modified proprietary connections due to the loadingsSpar environments introduce fatigue loading and stresses on tubing that requires additional testingGRE tubing had not been run in production prior to injection conditions in deep waterEach GRE connection is commonly drift checked after make-up; this is not suitable for many deepwater operations. The paper will detail the material selection for tubulars, the reasons for the product development and the final qualification testing. Installation experience of the product in several deepwater wells is described. Deepwater water injection wells often cost more than producer wells. Cost is increasing as material prices continue to rise. On a project scope, the cost savings of non Duplex-CRA tubing is significant; thus the GRE manufacturer is now running the qualified product in many other deepwater projects for a variety of operators. As a result of this testing and qualification, GRE-lined tubulars are now being used for the majority of BP deepwater non HP HT water injection projects.

This paper presents a mathematical model of casing strings subjected to thermal loads in steam injection wells. The model includes the effects of temperature on material properties and the effects of wellbore curvature and pre-stress during the heating cycle. Several counter-intuitive aspects of the casing stress state during cooling/unloading are examined. Example calculations are used throughout to illustrate key insights. Introduction The design and development of steam injection fields is a mature subject. Since the tubulars in these wells invariably experience inelastic loading, issues such as the effects of temperature on the static and cyclic (fatigue) material properties become important. The original papers that address steam injection casing design issues date back to the 1960s. These studies include temperature prediction1, casing stress analysis2 and development of design guidelines3. Though these works acknowledge the role of temperature on the static and cyclic material properties, data on the cyclic thermal properties of OCTG steels rarely appears in oil field literature4,5. This paper presents a mathematical model of casing strings subjected to thermal loads in steam injection wells. The model includes the effects of temperature on material properties and the effects of wellbore curvature and pre-stress during the heating cycle. Several counter-intuitive aspects of the casing stress state during cooling/unloading are examined. Further, the general equations are shown, with appropriate simplifications, to reproduce the earlier work cited above2,3. Example calculations are used throughout to illustrate key insights. Governing Equations for Steam Stimulation Consider a deformation for which the strains are small enough to be characterized as infinitesimal. Then we may write the total strain rate as Equation (1) In developing a multi-dimensional, thermomechanical constitutive relation, we honor available experimental evidence that suggests that both the viscoelastic and plastic components of the deformation depend exclusively on the deviatoric tensors, with hydrostatic behavior being purely elastic, i.e. the mean components of the viscoelastic and plastic strains (and strain rates) are zero. In this regard, we introduce the deviator strain and stress tensors Equation (2) Equation (3) where for and for , and Equation (4) Equation (5) where a repeated subscript index indicates summation over the range 1 to 3. Similar definitions for deviatoric and mean elastic, viscoelastic and plastic strain rate components can also be written. The mean elastic strain rate is related to the mean stress rate by Equation (6) and from our previously stated assumption Equation (7) The mechanical constitutive relations for the deviatoric components are as follows.

Current models of slip crushing treat the rotary slip as an axisymmetric wedge that generates an axisymmetric radial load on the drillpipe lateral surface. However, recent tests on strain gauged drillpipe specimens suggest that this model does not adequately capture the mechanical response of the drillpipe. The tests show that drillpipe response is a complex and non-axisymmetric function of slip geometry, friction between the slip and the bowl in the rotary table, and the mechanics of load transfer between the slip and drillpipe. This paper presents a new model of slip behavior that represents the slip system as a series of line loads. Analysis of the suspended tubular under these forces and axial tension leads to a limit load that characterizes slip crushing. A corollary of this analysis is the minimum slip length required to support a given axial tension. Background The failure of drillpipe in the region of contact between the drillpipe and slips was first addressed by Reinhold and Spiri in 19591. This paper recognized that drillpipe is subjected to bi-axial loading in the slip contact area. By treating the slip as an immovable wedge between a rigid bowl and the hanging drillpipe, a relation between the axial force on the drillpipe and the transverse force exerted on it by the slips was derived. The ratio of the transverse force to the axial force known as the "K-factor" is given by (1) The angle of taper has been standardized by the API to 90, 27′, 45″. The average radial pressure on the drill pipe outer diameter and the axial stress in the pipe beneath the slip toe are estimated. This "radial pressure" is used to estimate the tangential stress at the drillpipe inner diameter. Knowing the tangential and axial stresses on the inner diameter of the drillpipe (where the radial stress vanishes), the von Mises equivalent (VME) stress criterion is used to estimate the axial load at which the drillpipe begins to yield. The Reinhold-Spiri formula for the slip crushing load is,(2) The predictions of Eq. (2) were compared with a limited series of meticulous tests on 5 in., 19.5 ppf, Grade E drill pipe loaded in standard and extended length manual slips2. Until recently, Eq. (2) has been used to calculate slip crushing loads for drillpipe and casing hung in rotary slips, and sometimes to calculate the loads exerted by packers on tubing. Eq. (2) is based on a statically determinate analysis of a conical wedge, a consequence of which is that the peak stress is always on the drillpipe inner diameter in the vicinity of the slip toe. An unstated consequence of the assumptions leading to Eq. (2) is that the drillpipe stress distribution is axisymmetric. This theory thus implies that the peak stress region is a circle on the drillpipe inner diameter in the plane of the slip toe. Following the work by Reinhold and Spiri1 and Vreeland2. in the late 1950s, slip crushing analysis received little attention until 1985. A 1985 paper by Hayatdavoudi discusses the principles of slip insert design to reduce probability of yielding in the pipe3. The work includes representation of strain gage data from slip crush tests on 9–5/8 in., 53.5 ppf casing. Though the paper does not contain the details of testing, the data presented in this paper indicates that the deformation of the casing inner diameter above the toe of the slip is larger than the deformation near the top of the slip.