HDDW is a subsurface intake system for desalination plants. Several intake systems are discussed in this article, amongst others horizontal wells or drains. The most important aspects that are mentioned in this article are geology, lack of long-term operating data and the ability to clean a (partially) clogged screen. This was one of the key researched items in the development of HDDW. Clogged screens scan be regenerated with specialized cleaning tools. Furthermore, by our patented method to install a gravel pack around the filter, the flow velocities are lowered and mechanical clogging is reduced significantly, while maintaining a high capacity.
Summary of the article
This is the official summary of the article:
The use of subsurface intake systems for seawater reverse osmosis (SWRO) desalination plants significantly improves raw water quality, reduces chemical usage and environmental impacts, decreases the carbon footprint, and reduces cost of treated water to consumers.
These intakes include wells (vertical, angle, and radial type) and galleries, which can be located either on the beach or in the seabed. Subsurface intakes act both as intakes and as part of the pretreatment system by providing filtration and active biological treatment of the raw seawater. Recent investigations of the improvement in water quality made by subsurface intakes show lowering of the silt density index by 75 to 90%, removal of nearly all algae, removal of over 90% of bacteria, reduction in the concentrations of TOC and DOC, and virtual elimination of biopolymers and polysaccharides that cause organic biofouling of membranes.
Economic analyses show that overall SWRO operating costs can be reduced by 5 to 30% by using subsurface intake systems. Although capital costs can be slightly to significantly
higher compared to open-ocean intake system costs, a preliminary life-cycle cost analysis shows significant cost saving over operating periods of 10 to 30 years.