26 Apr 2024

Follow Hilary Hall’s Churchill Fellowship travel blog

RMCG Senior Consultant Hilary Hall is travelling throughout Europe from April to June 2024 to investigate technology and policy approaches that enhance the beneficial use of biosolids.

Hilary’s Fellowship from the Winston Churchill Trust (Australia) will focus on biosolids, a by-product of sewage treatment and a valuable source of nutrients, organic matter and beneficial microbes for our soils.

Biosolids are an excellent example of circular resources, however this circularity is threatened by contamination from chemicals used in our food, clothing, cosmetics and pharmaceuticals. Solving this problem will take a multilateral approach, including government policy, environmental regulation, source control and technology solutions.

Hilary hopes her learnings contribute to better outcomes for biosolids management in Australia, improving resource recovery for the benefit of water utilities, farmers and communities.

A Churchill Fellowship offers Australian citizens and permanent residents a life-changing opportunity to travel overseas for four to eight weeks to learn more about a topic or issue that they are passionate about. You can read more about Hilary’s Fellowship or see this recent article from the Australian Water Association.

Follow Hilary’s blog below to receive the latest updates from her travels.

26 April 2024: Welcome!

Welcome to my biosolids travel blog. As I undertake my Fellowship, I’ll share a few posts about my journey throughout Europe and the UK, as I seek to understand biosolids treatment, regulation and use in this part of the world.

I’m looking forward to learning about different regulatory approaches, and what biosolids problems they have (and haven’t!) solved.

Map and itinerary

Hilary Hall Churchill Fellowship map 2024

10 May 2024: Bonjour from France!

The Paris Sewer Museum seemed like a good place to start my Fellowship tours. Yes, this is really a thing, there were lots of other visitors there, and it is a real, live, operational sewer!

Paris has a combined wastewater and stormwater system, and large underground galleries (photo 1) have been built over the last 150 years to provide sufficient capacity for wastewater and stormwater collection. Although the ‘modern’ sewer system has been developed in this time, the city has a history of conveyancing infrastructure dating back to 1370. The sewer galleries run throughout the city, mostly following the streets above, and sit only a few metres below the ground, above the Metro train tunnels.

Initially, wastewater was conveyed to the Seine River, downstream of the city. But during the 1850s, there was keen interest in utilising the nutrients in the wastewater for agriculture, and this led to the construction of an irrigation system eventually covering 50 square kilometres of agricultural land. Untreated wastewater was irrigated onto farmland from 1868 through to the First World War. After this time, direct irrigation was phased out (due to urban encroachment and increasing flows) and replaced with six wastewater treatment plants.

The sewer galleries are filled with an array of fascinating technologies. There is significant grit removal infrastructure, as the galleries have very little gradient and therefore grit accumulates rapidly. The suspended barge (photo 2) is lowered into the flow and used to create an eddy that causes grit to accumulate (photo 3), so that it can be pumped out efficiently. These barges are permanently installed throughout the sewer network and have been in operation since 1865.

The sewer galleries also house thousands of kilometres of water mains, fibre optic cables and other services (photo 4). Paris is serviced by both potable water and non-potable water (untreated river water). The non-potable supply was installed specifically to water the spectacular gardens throughout the city, for which Paris is renown.

The ingenuity, scale and history of the Paris sewers is incredible. Walking through an operational sewer made me appreciate how essential they are to the city above; all that beauty would not be possible without this infrastructure below.