Smaller treatment plants help make much-needed water and wastewater more viable
Decentralized water and wastewater treatment is an alternative to the dominant centralized infrastructure model, which typically uses a large-scale treatment plant to serve a municipality and its outlying areas. Frequently, the plant is miles away from its most distant customers, and this distance can be problematic.
In contrast, the decentralized model uses smaller plants placed at the source of need to handle the same capacity. Decentralized treatment has many advantages, not just in terms of resilience and cost, but also for the environment. What exactly does decentralization have to offer?
Decentralization can expand treatment to locations that currently discharge their sewage into the environment untreated. Many smaller and more remote communities simply find it difficult to raise capital to build or connect to centralized systems. Often, there’s no ready alternative to discharging untreated wastewater.
For instance, a recent estimate suggested that among Caribbean islands, 80% of untreated wastewater is discharged, causing incalculable harm to sensitive tropical reef ecosystems, as well as economic harm to potential tourist economies.
The expense that puts traditional centralized infrastructure out of reach is largely due to the extensive pipelines they require. However, smaller decentralized plants can be located directly at the source of need, eliminating pipeline obligations. With decentralization, environmental protection is affordable for a rapidly expanding group of communities and regions.
Benefits of Water Reuse
Keeping treatment local also allows for safe wastewater reuse where it was never possible before. While some communities use untreated wastewater for agricultural irrigation, the practice comes with serious public health risks. But, the high cost of a return pipeline from a central treatment plant would be prohibitive.
Treating water locally with a small, decentralized plant allows safe water reuse for a long list of nonpotable applications, from agricultural irrigation to toilet flushing. Reuse virtually increases the supply of water available for communities, which in turn relieves the demand on natural systems. Natural surface and groundwater can then recover from overuse, which produces cascading positive effects for ecosystem restoration.
The steady supply of fresh water produced through desalination can prevent or reverse the depletion of natural surface and groundwater that ecosystems rely upon.
With thoughtful impact analysis and proper siting, impacts to aquatic ecosystems can also be minimized. Seven Seas Water Group’s Point Fortin plant on Trinidad, for example, is larger than a typical decentralized plant and discharges more brine, yet it has still been hailed for its minimal ecological impacts.
The positive impacts of decentralized desalination for terrestrial ecosystems also should be considered. On the Mediterranean island of Malta, for instance, reliance on small-scale desalination and wastewater reuse is protecting the island’s fragile ecosystems by preventing overuse of natural groundwater, which can help prevent saltwater intrusion into aquifers.
Additionally, the Maltese have found that brine discharged from their smaller plants is less problematic for marine ecosystems.
Smaller Scales and New Financing Models
The smaller size of decentralized facilities alone makes projects more practical, with smaller equipment, a smaller pool of conflicting political interests, and the opportunity to use modular equipment that can simplify construction and lower costs. But even with the significant savings associated with decentralized plants, water infrastructure still represents a large capital commitment.
Fortunately, financing models such as public-private partnerships (P3), build-own-operate (BOO), and build-own-operate-transfer (BOOT) models can make updated infrastructure a reality for undercapitalized entities.
Seven Seas’ Water-as-a-Service® offers P3, BOO, and BOOT performance-based agreements to bring decentralized treatment to under-served areas. Healthy ecosystems can coexist with healthy economies through decentralization. Contact Seven Seas to find out how.