Reuse of treated sewage effluent for irrigation

I refer to the press conference held by the Malta Water Association wherein it called for treated wastewater to be reused and not dumped at sea (September 15).

Ever since the former drainage department was incorporated within the Water Services Corporation in 2004, the immediate objective was to have the Maltese islands comply with the urban waste water directive. After reviewing the Malta sewage master plan of 1992, drawn up by Danish and updated by German consultants in 2002, the corporation drew up its own plans to implement this ambitious programme. These plans were examined in detail by EU-appointed experts before the go-ahead was given to tap into EU funds.

In spite of the many huge difficulties we faced and within the finances available, by the beginning of 2011 the WSC had built three sewage treatment plants. So, once Malta was now completely in line with the EU urban waste water directives, we could sharpen our focus on treated sewage effluent (TSE) reuse.

As soon as the first plant located in Gozo began operating the WSC set up a team of engineers to study the characteristics of the TSE. However, treatment plants need a good infrastructure to convey wastewater to them, so a review of the master plan for the sewage infrastructure was prepared, which identified those critical areas where salinity was high (i.e. salty water was entering the sewage system) and major interventions were necessary. Therefore, WSC started tackling the worst areas having the highest impact on the wastewater reaching our treatment plants.

In tandem with the above the WSC laboratory began a campaign to raise awareness among commercial entities so that they managed their discharge effluent. These steps were necessary since sewage treatment plants are only designed to handle urban wastewater so that their discharges do not cause damage to the environment.

Treated effluent reuse, however, goes beyond the scope of sewage treatment plants and we always planned for potential reuse without the need of any retrofitting to the plants.

With these issues in mind the corporation continued researching the best technologies available. Using its expertise in water technologies and in collaboration with international organisations, in 2009 the WSC installed a pilot plant in Gozo. The corporation monitored results over a period of six months before relocating the plant to other areas. It is currently operating at Ta’ Barkat to test the effluent reuse potential in that area.

This time-consuming process was necessary since the corporation was anxious to avoid the difficulties caused by the treated effluent produced by the old Sant’ Antnin plant. Furthermore, new regulations covering food safety and the potential to artificially recharge our depleted and damaged aquifers, meant the corporation would have to address these aspects as well.

Malta, like most EU countries, lacks a proper regulatory framework on treated effluent reuse. Therefore, while keeping abreast of the developments in technologies, the corporation also needed to follow up on developments in regulations, which is being done by a group of professionals.

The corporation has now reached a stage where it has a dedicated team drawing up the technical specifications for the construction of phase-two plants. These will be based on polishing plants using ultra-filtration and reverse osmosis membranes coupled with disinfection.

Additionally, the corporation is also preparing distribution networks containing hydrants for water tanker applications. These are due by the begininng of 2013 depending on permits and funds’ availability.

Discussions with the Malta Environmental and Planning Authority, Malta Resources Authority as well as the Planning and Priorities Coordination Department are ongoing. The corporation is also working with the Ministry for Resources and Rural Affairs for additional networks that the ministry is planning to service and support the farming community.

The issues mentioned above are extremely complex so the importance and coordination of all these efforts should not be underestimated.

The corporation is committed to eventually provide a safe, high-quality product while keeping the operational costs as low as possible. But it will only do this after having exhausted all efforts at using the best technology and work practices available.

This information has time and again been made available to members of the Malta Water Association as we believe in their positive contribution towards the common good.