The significance of dilution in evaluating possible impacts of wastewater discharges from large cruise ships

Loehr, Lincoln C.; Beegle-Krause, CJ; George, Kenwyn; McGee, Charles D.; Mearns, Alan J.; Atkinson, Marlin J.

doi:10.1016/j.marpolbul.2005.10.021

Cited by 25 publications

(8 citation statements)

References 1 publication

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“…The small cruise ships' passenger capacities are less than 500. The studies offered that the Equation (1) can be used by multiplying with '3' for small cruise ships due to the similar hydrodynamic characteristics of big and small ships [22]. The dilution factor equation for small ships as is follows:…”

Section: Dilution and Dilution Factormentioning

confidence: 99%

Determination of Wastewater Behavior of Large Passenger Ships Based on Their Main Parameters in the Pre-Design Stage

Şahin

Vardar

2020

JMSE

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Wastewater formed on ships is divided into blackwater and graywater. While blackwater refers to wastewater from toilets, graywater defines wastewater from sinks, laundry and restaurants. Even though some treatments are applied onboard before discharge, wastewater contains significant amounts of fecal bacteria, heavy metals, etc., in excess of water quality standards. Dilution is a secondary natural treatment in the ship-wake region, which occurs after wastewater discharging. According to the Environmental Protection Agency (EPA), the natural treatment process is quantified by dilution factor, which is strongly dependent on vessel width, draft, speed and wastewater discharge rate. In this study, an Artificial Neural Network (ANN) model linked with the main ship parameters was developed to estimate the dilution factors while the ship is in the preliminary design stage. Gross ton, deadweight ton, passenger number, freeboard, engine power, propeller number and block coefficient values of 1041 large cruise ships were used to estimate the likely dilution factors. The best ANN estimation model was determined by Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) methods. A decision tree was created for the results and the most important parameters affecting the dilution factors were determined. The main ship dimensions are needed for the dilution factor formulation of EPA whereas in the model created in this study only the gross ton or engine power of the ship is sufficient to estimate the dilution. Moreover, this new model is also usable for the estimation of dilution factors even if the main dimensions of the ship are not known.

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Section: Dilution and Dilution Factormentioning

confidence: 99%

Determination of Wastewater Behavior of Large Passenger Ships Based on Their Main Parameters in the Pre-Design Stage

Şahin

Vardar

2020

JMSE

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“…The dilution of acid mine water created a more favourable environment for the Hydra (Bell and Wolfe, 1985;Holdway, 2005). In a study by Loehr et al (2006), dilution of wastewater discharges resulted in the effluent being less toxic to aquatic organisms when conducting WET (whole effluent toxicity) testing. The decrease in sensitivity could also have been as a result of the Hydra metabolising toxicants in the water sample (Quinn et al, 2009) and thereafter adapting themselves to the conditions.…”

Section: Discussionmentioning

confidence: 99%

A comparison between <i>Daphnia pulex</i> and <i>Hydra vulgaris</i> as possible test organisms for agricultural run-off and acid mine drainage toxicity assessments

Singh

Nel

2017

WSA

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“…where: D: dilution factor c: constant equivalent to 0.0030 for a single discharge orifice or 0.0045 for two discharge orifices Q: volume discharge rate U: vessel speed L: waterline length t: time after disposal Further field testing (Byrne et al, 1988;Chou, 1996), however, showed that this formula underestimates the dispersal rate by 3 to 10 times. Other studies considered the dilution following discharges from large cruise ships (US-EPA, 2002; Loehr et al, 2006). Katz et al (2003) simulated the dilution of pulped waste materials into the wake of a US Navy frigate, carrying out field measurements and computer modeling.…”

Section: The Fluid Dynamics Of Slaked Lime Discharge At Seamentioning

confidence: 99%

Potential of Maritime Transport for Ocean Liming and Atmospheric CO2 Removal

et al. 2021

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Proposals to increase ocean alkalinity may make an important contribution to meeting climate change net emission targets, while also helping to ameliorate the effects of ocean acidification. However, the practical feasibility of spreading large amounts of alkaline materials in the seawater is poorly understood. In this study, the potential of discharging calcium hydroxide (slaked lime, SL) using existing maritime transport is evaluated, at the global scale and for the Mediterranean Sea. The potential discharge of SL from existing vessels depends on many factors, mainly their number and load capacity, the distance traveled along the route, the frequency of reloading, and the discharge rate. The latter may be constrained by the localized pH increase in the wake of the ship, which could be detrimental for marine ecosystems. Based on maritime traffic data from the International Maritime Organization for bulk carriers and container ships, and assuming low discharge rates and 15% of the deadweight capacity dedicated for SL transport, the maximum SL potential discharge from all active vessels worldwide is estimated to be between 1.7 and 4.0 Gt/year. For the Mediterranean Sea, based on detailed maritime traffic data, a potential discharge of about 186 Mt/year is estimated. The discharge using a fleet of 1,000 new dedicated ships has also been discussed, with a potential distribution of 1.3 Gt/year. Using average literature values of CO2 removal per unit of SL added to the sea, the global potential of CO2 removal from SL discharge by existing or new ships is estimated at several Gt/year, depending on the discharge rate. Since the potential impacts of SL discharge on the marine environment in the ships' wake limits the rate at which SL can be applied, an overview of methodologies for the assessment of SL concentration in the wake of the ships is presented. A first assessment performed with a three-dimensional non-reactive and a one-dimensional reactive fluid dynamic model simulating the shrinking of particle radii, shows that low discharge rates of a SL slurry lead to pH variations of about 1 unit for a duration of just a few minutes.

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The significance of dilution in evaluating possible impacts of wastewater discharges from large cruise ships

Cited by 25 publications

References 1 publication

Determination of Wastewater Behavior of Large Passenger Ships Based on Their Main Parameters in the Pre-Design Stage

Determination of Wastewater Behavior of Large Passenger Ships Based on Their Main Parameters in the Pre-Design Stage

A comparison between <i>Daphnia pulex</i> and <i>Hydra vulgaris</i> as possible test organisms for agricultural run-off and acid mine drainage toxicity assessments

Potential of Maritime Transport for Ocean Liming and Atmospheric CO2 Removal

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