#15 | Unsolved problem of wastewaters salinity

By Wojciech Mikołajczak (IMN)

Over three decades ago, in 1991, first significant European Directive (91/271/EEC), concerning
collection, treatment and discharge of waste waters from cities and “certain industrial sectors” was
passed. Since that time, many efforts were made to protect the environment from adverse effects of
human activities. Since that time, countless additional legislation concerning industrial emissions in
general (Directive 2010/75/EU), particular sectors of industry such as mining (Directive 2006/21/EC)
and particular types of wastes (WEEE Directive 2012/19/EU). Moreover, there are a number of
relevant communications which are worthy of particular attention due to the strong link to the EU’s
circular economy such as The European Green Deal and Critical Raw Materials Strategy.

It is particularly necessary to treat polluted effluents to protect European water bodies from harmful
discharges and these environmental aims at EU level were declared in the Water Framework
Directive (Directive 2000/60/EC). It was intended to achieve a good status for all water bodies.
Unfortunately, discharge limits of sulphates, chlorides and sodium remain solely in charge of
Members State. According to WHO´s guidelines for drinking-water quality, these should not exceed
500, 250 and 200 mg/l respectively.

Some examples of legislation in Europe

In Germany, any discharge of wastewater requires a permit according to water legislation on the
basis of the Federal Water Act (Wasserhaushaltsgesetz – WHG). Particular discharge requirements
and limits for effluents are defined separately by their origin or nature since 2004 by additional
Wastewater Regulation (Abwasserverordnung – AbwV).Guidelines excludes chlorides and sulphates,
and task of setting discharge thresholds in every particular water permission remains assigned to
local authorities.

Different approach is presented by polish regulations. Discharge limit for industrial wastewaters and
water from dehydration of coal mines includes salinity – concentration of chlorides and sulphates
may not exceed 1000 and 500 mg/l respectively. Additionally three exception are included:

1) waters introduced to the territorial sea – without restrictions;

2) waters introduced to the flowing surface waters – if the total calculated content of chlorides and
sulphates, assuming full mixing, does not exceed 1 g/l;

3) if these conditions, and the use of an appropriate technical solution is impossible or economically
unjustified, it is allowed to increase the sum of chlorides and sulphates, as long as it does not cause
damage in the aquatic environment and will not hinder the use of water by other users.

Further discrepancies in environmental policies of particular Member States may only undermine
previous efforts and lead towards catastrophes, such as fish die-off in the Oder River in August 2022.
Ironically, according to authorities from both banks of these border river, Poland and Germany, main
cause of these event was high salinity. Neither side took responsibility.

Table 1. Comparison of discharge limits in Poland and Germany, in mg/l unless stated otherwise.