‚EXTE Environmental Impacts of Exhaust Gas Cleaning Systems for Reduction of SOx on Ships — Analysis of status quo 
Report compiled within the framework of the project ImpEx 
Compound | Proposed limit values ® ı 
(u8/L) 
Local limit values ” | Measured concentrations © 
Tier 1 | 
Tier 2 | 
Tier 3 
| HSY 
SV P95 | 
ADEC1 | ADEC2 
OL 
0.09 120 
6 — 440 
12 — 860 
CL 
0.16 — 3.8 
220 — 6 600 
2 800 — 25 000 
Lead 
Nickel 
Vanadium ! 
50 
50 
NA 
NA | na | 3.000 | 200 | 
43 
43 
NA 
NA 
Zinc | NA | 
Legends: 
4SY — HSY Helsinki Region Environmental Services Authority 
5V P95 — Guidelines according to Svenskt vatten’s Publication P95 
ADEC1 — The Alaska Department of Environmental Conservation. These limits concern discharge of treated sewage and 
treated grey water. There are technology based effluent limits. The presented values are from limits category “Other 
Treatment System”. These effluent limits apply to wastewater discharge while docked, anchored, or moving at a speed 
Jelow 6 knots. 
ADEC2 — Similar to ADEC1. These effluent limits apply to wastewater discharge while underway travelling at a speed of 6 
<nots or greater. 
OL —- Open loop EGCS 
CL - Closed loop EGCS 
NA — Not applicable. Compound is not considered in the proposed or existing regulation. 
sources: a) Adapted from Norway and Finland (2006); b) Adapted from Lahtinen (2016); c) As reviewed from different 
research works and summarized in Table A-4. 
360 | 360 
2 -450 
40 — 2 400 
6.4 Nitrates 
The current “2015 EGCS Guidelines” specify the following requirements for the EGCS discharge 
water, being applicable whichever the greater value is: 
1. Nitrates concentration < that associated with a 12% removal of NOx from the exhaust, 
or 
2. Nitrates concentration <= 60 mg/L normalized to a specific flowrate of 45 m*/MWh. 
This criterion does not take into account the contribution of the current environmental 
concentrations. However, in the drafted review of the “2020 EGCS Guidelines” the 
considerations of the inlet water are taken into account. 
While the inclusion of a discharge criterion for nitrates in the EGCS Guidelines seems tobe a 
measure to prevent eutrophication and, to a certain extent, acidification effects, the definition of 
the limit values may take into account other factors. In document BLG 12/6/11 (Finland, 2007) 
an explanation for the origin of the mentioned discharge criteria was found. Finland (2007) 
explains that “with the nitrate clause the intention of the IMO is to address cleaning devices 
designed to remove NOx, not to complicate the introduction of normal SOx-scrubbers”. To this 
regard, GESAMP (2009) understood the nitrates criterion as “intended to cover the event of a 
hypothetical scrubber (...) also removing extensive amounts of NOx beyond the soluble NO; fraction 
likely to be partly removed”. The maximum allowed NOx removal (12%) from the diesel engine 
exhaust was taken as this is considered the maximum amount of NOx that can be dissolved in 
washwater by normal EGCS and the concentration (60 mg/L) was derived from that number 
(Finland, 2007). This means that unless the EGCS has special features for NOx removal, the 
nitrate limit value would not be exceeded by a conventional EGCS, designed only for SOx 
removal. In the reviewed IMO documentation, no information or study was found presenting an 
environmental assessment to demonstrate that the release of EGCS discharge water with nitrate 
concentration below the set limit does not impair the marine environment.