Wastewater treatment – the invisible benefits of civilisation (Part 1)

• Introduction
• Prehistory (from the origin of man to the 4th millennium BC)
• Ancient history (from the 4th millennium BC to the end of the 5th century )…
• Medieval (476m Va. – 15th century)

Introduction

Since ancient times, we humans have had to take care of our cleanliness and daily needs – washing, bathing, cooking, washing dishes and using the toilet. But have we ever considered that the modern technologies for wastewater management that we now take for granted are actually quite new, given the long history of mankind?

Sewage systems have been around for thousands of years. And in the ancient Roman Empire, sewage was so important that it even had its own patron goddess, Claocina, who was worshipped in a shrine in the Roman Forum. And while the technology of the time seemed astonishing, it was only the first step in a long quest for civilisation to improve quality of life and preserve health and lives.

I invite you on a journey through history, during which you may discover that the development of wastewater treatment technology, which in our time has become an indispensable part of our environment and the well-being of our society, has had a long and not always easy road.

Prehistory (from the beginning of man to the 4th millennium BC)

Sewage is a constant companion of our civilisation
Before we were simply hunters and gatherers, we lived in a world where we used what nature had to offer, and the environment dealt with our waste in the circle of life.

But everything changed when we became farmers, producers and traders. More and more hands were needed to do the work, so more and more settlements and towns were built, and the amount of waste grew. Already by 4000 BC, waste and waste products were increasing. By 4000 4000 AD, the Babylonians had applied their knowledge of hydraulic water transport to the conveyance of the contents of toilets into wells. I believe that this is the time when sewage, the constant companion of our civilisation, came into being.

Exceptional examples of water and sewage systems in ancient India
One of the oldest surviving sewerage systems has been found in ancient India (modern Pakistan) in the ruins of the cities of Harappa and Mohenjo-Daro. The excavation of these cities has revealed that already around 2600-1900 BC, exceptional examples of water and sewerage systems were constructed, forming a modern water management system with numerous reservoirs. Sewage from houses was discharged through underground drains built of precision-built bricks, which were connected to a wider network of sewers in the main streets. The sewers had holes at regular intervals which were used for cleaning and inspection. These systems allowed ancient towns to have a continuously running water supply and to collect sewage from houses and public baths. These were the first technologies for wastewater treatment and I am really impressed by the magnificent buildings that have survived from that time and by the ingenuity of the people of that period.

 

Excavated ruins of Mohenjo-Dvar with the Great Bath

Ancient history (from the 4th millennium BC to the end of the 5th century )

The title of champions of sewer construction is usually given to the Romans
And this title is due to the famous “Cloaca Maxima”, the largest and most famous sewage system, which began to be built in the 6th century BC and is still in existence today. The Cloaca Maxima is believed to have been a natural stream that was used as an open drainage channel to drain the marshy lowlands between the Palatine and Capitoline hills, leading from the centre of Rome towards the Tiber River. The canal was lined with stone to make it more efficient. Construction was started by Etruscan* craftsmen, who were at that time experts in sewers, sluices and soil reclamation. (The Etruscans, an ancient people who lived in north-central Italy, were later conquered by the Romans) and the Romans took over the art of building from them.

“Cloaca Maxima Roman pride and engineering success
In the following decades, as the city developed, the sewage network expanded and grew. Roman craftsmen were already building other canals, constructing collectors in the areas of larger buildings, connecting them to the main canal of the Cloaca Maxima, improving and restoring them. As cities expanded, the canals were covered over and became true underground sewers. It acted as a central sewer system and received sewage from Rome’s streets, hotels, houses, palaces, popular public baths and public toilets.

However, it is important to note that even these older sewer systems did not have the complete treatment processes of today’s modern sewage treatment plants. The sewage flowing through the Cloaca Maxima canals was simply diverted into large tanks so that, once the gravel, sand and other sediments were deposited, the water could continue to flow directly into the Tiber River. This led to a huge contamination problem in the water wells of the centre of Rome and the surrounding water bodies.

Nevertheless, the Cloaca Maxima was a source of pride for the Romans and an engineering success that helped to channel some of the sewage. Although the system was not perfect, the efforts of the ancient Romans to treat wastewater show how people had long understood the importance of wastewater management in their communities. And my great respect to them for that.

Built of stone, the massive Cloaca Maxima is one of the oldest engineering monuments in existence

Medieval (476m Va. – 15th century)

No significant improvements in wastewater treatment in the Middle Ages
But worse, the collapse of the Western Roman Empire led to the destruction of many aqueducts and a bleak future for water. Natural water sources continued to be used to discharge wastewater. But most of the waste was simply poured into gutters in the streets and the streets were turned into open sewers with a horrible smell and a source of disease. In some towns, sewage pits were built as the only sanitary structure. However, in densely populated areas, local conditions quickly became intolerable as the tanks were rarely emptied and often overflowed. As all the waste water from the tanks seeped into the groundwater and into drinking water wells, it became a source of outbreaks of diseases such as cholera and typhoid.

It was a dark period when rats thrived on excrement and epidemics of cholera and plague swept through medieval Europe. Cities were polluted and hygiene was at its highest in the countryside, where peasants buried their excrement in pits.

A breakthrough in sewage management at the end of the Middle Ages
We cannot say that nobody cared about the situation at that time. There were attempts to take sewage out of the cities and to cover the sewers to protect against the stench that was spreading. Pumping stations were introduced, but this did nothing to improve the situation in the cities. One of the most successful attempts to manage wastewater at the end of the Middle Ages was made in Dubrovnik (then called Ragusa). The Republic of Ragusa adopted a Statute in 1272, which included instructions on town planning and sewerage construction. During the 14th and 15th centuries, the sewage system was designed, built and is still in operation today. Of course, it is now constantly being improved and restored, but Croatians are very proud of the achievements of that time in sewage treatment.

Dubrovnik’s historic sewerage system restored

We will present the story of the New Ages and the Recent Ages in the second part of “THE IMMEDIATE ADVANTAGES OF CIVILISATION”.