Automated Wastewater Treatment Plant on Cruisers

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Introduction

Adriatic Sea, as part of the Mediterranean, is one of thesemi-closed seas, and is therefore particularly vulnerable toall kinds of pollution.

For this reason, much attention has been paid to theprevention of various types of marine pollution from ships,

from oil pollution, problems of introducing a foreignspecies with ship's ballast waters and air emissions. There is not enough information of marine pollution from

ship's waste water. The increase of cruisers in the Adriatic arises questions

whether our sea is safe The aim of this paper is to explore the technology of

wastewater treatment on cruisers, the quality of dischargedwater and the impact on the purity of the Adriatic Sea.


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CRUISING TOURISM IN CROATIA


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WASTEWATER ON CRUISERS

Wastewater on board :1. sanitary wastewater : sewage containing feces or blackwater and wastewater from washing of marine livingquarters or gray water;

2. bilge water

Attributes which determine quality of wastewater:1. dispersed substances - amount of substances

dispersed in a unit of volume of water (mg/l or g/m3)

2. biochemical oxygen demand (BOD) which determinesthe amount of oxygen required to biologically break down

organic matter by microorganisms (mgO2/l)3. indicator organism - his presence in waste water indicates

that water may contain pathogenic organisms. As anindicator organism, coliforms are applied.


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Pollution with wastewater from cruisers

Impact of big cruisers on environment can becompared to an impact on environment of a small city.

Average daily pollution from a cruiser with 3000

passengers is: Black water: 60000 120000 l,

Grey water: 1020000 l,

Sludge: 25000 l.

PollutionRepublic of

CroatiaEU Cruiser

Wastewaterin liters

110-150 150 up to 340


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Technological processes of wastewater

treatment plant on cruisersWastewater treatment processes are classified

according to the substances that should be

removed from waste water on board.According to naval regulations regarding the

cleaning of ship's waste water before discharge intothe sea, particular goals for stages of cleaning are

set: previous or preliminary cleaning means application

of the procedures by which large, dispersed and floatingwaste matter is removed from the waste water,


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first stage or primary cleaning is the application of

physical and/or chemical cleaning processes thatremove at least 50% of suspended solids and reduce thevalue of BOD-5 for at least 20% compared to the value ofthe incoming water,

second stage or secondary cleaning means the use of

biological and/or other procedures that reduces theconcentration of suspended solids and influent BOD-5for 70 - 90%, and the concentration of COD (chemicaloxygen demand) for at least 75%,

third stage or tertiary cleaning is the application ofphysical-chemical, biological and other processes by

which the ship's wastewater reduces the concentrationof nutrients inf luent for at least 80%.


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Performances of wastewater treatment

plant on cruisers There are four systems for treatment of wastewater

from passenger ships so far.

SCANSHIP wastewater system represents advancedtechnology of wastewater treatment which is fullyautomated.

The quality of waste water after treatment by this

system is in accordance with the strictest standards.The system configuration consists of five cleaningmodules:


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5 cleaning modules:

1. pre-treatment module

filtering or separationof solid impurities,

2. biological treatmentmodule biologicaltreatment usingbioreactors,

3. flotation module flotation andflocculation usingreagents,

4. polishing module

polishing with a 30 mfilter,

5. UV module UVdisinfection.


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Test program for determination of qualittive

features of the wastewater treatment plant

When testing the degree of treatment representativesamples should be taken. Based on these samples we get

the right picture of the treated wastewater quality. Proper sampling of water for its analysis is crucial for the

assessment of water quality based on which cruiser will geta certificate of sanitary wastewater in compliance with theConvention, MARPOL 73/78 Annex IV

Representative samples must be taken several times a daybecause waste water has a very uneven flow andcomposition, which vary throughout the day.


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According to SCANSHIP wastewater system sampling isdone according to the following points:

Representative sampling is done at the exit of the UV unit orafter the last process.

A place for taking the samples must be heated using gasburners or electric heaters to destroy any possible bacteria at

the site of sampling. After disinfection a representative sample for coliform

bacteria, a minimum of two bottles of 100 ml is taken.

Then representative sample of the total amount of suspended

solids (TSS) in a volume of 1 l is taken. Then a representative sample of the biochemical oxygen

demand in five days (BOD-5) in the amount of 1 l is taken.

Value of pH as well as the amount of chlorine is taken fromsamples of total suspended solids.


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REGULATIONS FOR WASTEWATER DISCHARGE

FROM SHIPS INTO THE SEA

Discharge of sewage into the sea is prohibited, except when: ship discharges crumbled and disinfected sewage using an

approved system, at a distance greater than 3M from thenearest land, or feces, which are crushed and disinfected at a

distance greater than 12 M from the nearest land, with onecondition, that feces which are located in the tank for storageare not released at once, but in small amounts while ship issailing at speed not less than 4 knots or

ship has in operation an approved sewage treatment device for

which management has determined that it meets therequirements and that the results of testing of the device islisted in the International Certificate of preventing fecalcontamination from ship and, moreover, that in an outbreakthere are no visible f loating solids nor cause in a color change in

the surrounding water.


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Comparison of requirements for the quality

of discharged sanitary wastewaterSTANDARDS

MARPOL

73/78 Annex

IV

USCG in

general

USCG for

Alaskan

teritory

Croatian

Shipping

Register

BOD-5 [mg/l] 50 30 30 50

TDS [mg/l] 100 100 30 100

Coliform

bacteria [in 100ml of water]

250 200 20 250


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Although regulations of Croatian Shipping Register

correspond to MARPOL Convention, Annex IV, cruisersalways process wastewater only to that minimum level atwhich it complies with the regulations.

It is shown that representative system can meet stringentrequirements of Alaska resolution and discharge purified

wastewater with less than 30 mg/l of BOD-5, 30 mg/l ofTDS and 20 coliform bacteria in 100 ml of water.

US General Accounting Office recorded 104 cases ofintentional illegal waste disposals from cruisers from 1993

till 1998 which had been paid 30 million $.

In the past 10 years, U.S. authorities sued and collectedfines from cruise companies worth 100 million $.


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Automated Wastewater Treatment Plant on Cruisers

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