Feature 3 | BALLAST WATER AND WASTE WATER TREATMENT
Meeting tougher limits on sewage
discharge
Tightening controls on sewage discharge from ships give extra dimension to
the operational and technological challenges confronting the industry. IMO
MARPOL convention revisions, introduced in January 2010, look set to be
followed by further regional restrictions, says David Tinsley.
T
he revised MEPC 159(55)
MARPOL Annex IV standard
mandated that discharges of total
suspended solids within 12 miles of shore
be less than 35mg/l, compared to the
previous maximum of 50mg/l, and that
faecal coliform be limited to 100 colony
forming units per 100ml, down from 250
units per 100ml previously. Biochemical
oxygen demand (BOD5) is capped at
25mg/l, down from 50mg/l. The new
requirements apply to vessels above 400gt
and smaller vessels with a crew of 15 or
more, with a keel-laying date or sewage
plant installation or delivery on or af_t er
1 January 2010.
Regional restrictions that had already
This is the part
been put in place by the State of Alaska
had set some stricter ef_f_l uent standards
that saves you,
for ‘black’ (sewage), ‘grey’ (washing,
laundry, cleaning) and other waste water.
Total suspended solids under the Alaskan money.
controls have to be kept to below 30mg/l,
while faecal coliform is limited to less
than 20 units per 100ml.
Among the leading suppliers of marine
sewage treatment systems, UK-based
Hamworthy has developed a range of
solutions to meet the various standards.
As far as global regulations are concerned,
the company’s Super Trident STA-C and
ST-C plant is certif_i ed to meet the latest
IMO requirements, and has attracted Hamworthy MBR membrane arrangement as seen on MS Queen Victoria (Credit:
orders from shipbuilders worldwide. Hamworthy plc).
Incorporating aeration, settlement
and contact compartments, whereby the
latter provides for the introduction of discharge. separation, MBR technology yields
chlorine to kill bacteria, the Super Trident To meet still tighter controls on black the highest quality discharge without
designs are fully compatible with both and grey water release in especially necessitating the addition or generation
gravity and vacuum collection systems, sensitive areas such as Alaskan waters, of chemicals that may be hazardous to
and use activated sludge to accelerate Hamworthy has strengthened its product the maritime or shipboard environment.
natural biological processes. Chemical offering with a range of membrane In fact, the Hamworthy plant has been
Design Build Repair & Refit
disinfection and dechlorination are bioreactor (MBR) plants. Based on shown in tests to surpass existing and
Almost a Century of Experience. for the future
unique ships with quality & efficiency
employed to ensure clean, safe ef_f_l uent biological degradation and membrane upcoming regulations by a substantial
Astilleros Zamakona, S.A. Astilleros Zamakona Pasaia, S.L. Repnaval
Santurce - Bilbao - Spain Pasaia-San Sebastián - Spain Las Palmas de Gran Canarias - Spain
36 Ship & Boat International March/April 2010 t: (+34) 944 937 030
t: (+34) 944 937 030 t: (+34) 928 466 168
zamakona@zamakona.com
zamakona@zamakona.com
repnaval@repnaval.com
www.astilleroszamakona.com www.astilleroszamakona.com www.repnaval.com
SBI_MarApr10_p36-37.indd 36 01/03/2010 10:34:53 1/2 Page general.indd 1 18/7/08 10:35:24
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