Then results were compared to selected national and International water quality standards and land-based wastewater discharge limits, including the German Waste Water Ordinance, the EU Industrial Emissions Directive 2010/75/EU, and the EU Surface Water Standards Directive 2013/39/EU.
The study showed that the EGCS results compared favourably with all of these standards. Namely, the studied wash-water parameter concentrations were below the emission limits for land-based industrial point source waste water standards. CSA 2020 commented on this that:
This is not evidence of compliance with these standards (which are intended for a different regime and include other controls and limits for compliance than quality criteria). The comparison does however establish a point of reference to understand the quality of EGCS wash-water relative to other industrial discharges
In addition, very low and negative net post-EGCS values for certain wash-water parameters present a minimal contribution to the concentration of these parameters from the EGCS process (Arsenic, Cadmium, Lead, Mercury, Selenium, Thallium).
Moreover, the wash-water parameter concentrations also compared favourably to stricter water quality standards such as the EU surface water standards for inland waters. CSA 2020 once again noted that these standards have very different application and this comparison is not a definitive assessment of point source washwater quality. Nonetheless, they do provide a quantitative reference to understand wash-water parameter concentrations, especially for PAH compounds where there is absence of more suitable standards.
Furthermore, the average net Post-EGCS concentrations were calculated for ease of comparison. This means that values may not be representative of an individual vessel, considering the variance of the samples, and various operational conditions of each vessel.
Providing his comment on the results of the study, Ian Adams, Executive Director, CSA 2020, stated:
We want to emphasise that this major study was intended to provide an objective assessment of the quality of scrubber wash water through a rigorous comparison to other world water quality standards, and it now represents the largest, most credible and verifiable data set available. And importantly, the results reaffirm that exhaust gas cleaning systems are effective and safe for the ocean environment