Desalination, Coastal Solutions, and AVN Machines: Enhancing Water Sustainability
Microtunnel Boring Machines (MTBM)
Trenchless Installation Methods
Desalination is a process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance, as in soil desalination, which is an issue for agriculture.
Saltwater (especially seawater) is desalinated to produce water suitable for human consumption or irrigation. The by-product of the desalination process is brine. Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on the cost-effective provision of fresh water for human use. It is one of the few rainfall-independent water resources along with recycled wastewater.
Advancements in Tunnel Excavation Technology for Diverse Geological Conditions
Due to its energy consumption, desalinating sea water is generally more costly than fresh water from surface water or groundwater, water recycling, and water conservation. However, these alternatives are not always available and the depletion of reserves is a critical problem worldwide.
An estimate in 2018 found that "18,426 desalination plants are in operation in over 150 countries. They produce 87 million cubic meters of clean water each day and supply over 300 million people." The energy intensity has improved: It is now about 3 kWh/m3 (in 2018), down by a factor of 10 from 20-30 kWh/m3 in 1970. Nevertheless, desalination represented about 25% of the energy consumed by the water sector in 2016.
More than half of the world’s population lives within 60km of the coastline. Therefore, the construction of outfall tunnels is often an effective and sustainable solution to improve the quality of life in coastal areas. With the help of sea outfalls, wastewater can be discharged far away from the coast to allow for its better diffusion, dispersion, and dilution. In this context, municipal wastewater may be fully treated or pre-treated.
AVN Machines belong to the category of closed, full-face excavation machines with a hydraulic slurry circuit. The soil to be excavated is removed using a cutter head adapted to the respective geology. This makes it possible to use the machines in almost all geological conditions. In soft soils and mixed geologies, standard or mixed ground cutter heads are used, while a rock cutter head with disc cutters is used for tunneling in stable rock formations. A cone-shaped crusher inside the excavation chamber crumbles stones and other obstructions to a conveyable grain size while tunneling and advancing. Afterward, the material falls through openings similar to a strainer in front of the suction port and is removed through the slurry line and the suspension. The excavation diameter can be enlarged using an upsize kit and a modified cutter head. This means that the AVN Machine can be used to tunnel different diameters and for different types of pipes.
In cohesive soils, in particular, keeping the crusher cone clean and avoiding clogging is a special challenge. Based upon years of practical project experience, Herrenknecht has developed a range of water nozzle options, which can cope with different geological requirements. Additional water can be injected to clean the system using high-pressure nozzles integrated into the cone crusher. These jets cut loam or clay in the excavation chamber avoiding clogging. The medium-pressure nozzles use the standard slurry ports. Changing the size of the nozzles can adapt the suspension pressure and optimize the material flow. A newly developed, optional camera system in the excavation chamber provides the operator with an additional tool to visually monitor wear and tear and verify the situation inside machines with a more than 1.2 meters diameter.
In conclusion, desalination stands as a crucial method for addressing water scarcity, providing clean water through energy-intensive processes. Advancements have made it a vital source for millions. The synergy of desalination and innovative excavation, like AVN Machines, showcases human ability to conquer hurdles and serve coastal populations.
Sea outfalls further improve coastal life by managing wastewater and enhancing environmental conditions. Amid water challenges, the fusion of these solutions highlights human resolve to create a sustainable future.
In desalination, excavation innovation, and strategic planning, we find the keys to combat water scarcity. With ongoing progress, we can confidently navigate challenges and nurture a thriving planet.