As we have already mentioned several times at Seeders Media, most of the Waste to Energy projects mooted are failure or with low or no profits due to lack of feasibility and high economic investments, that’s why we created our Zero Waste Zones, but what can be done in terms of waste management?
In a centralized waste management systems all unsegregated waste will be dried using bio driers (to remove all moisture from the waste), and then will be converted to energy through gasification but the cost of procuring energy will be higher. A centralized one shifts focus from the source of waste generation to waste disposal sites. It also involves a large economic investment.
At a time when everyone is moving to decentralized waste management processes to reduce the impact of factors that lead to climate change, why are still cities implementing a centralized process, which has a high cost of treatment and further increases pollution. Such centralized waste management has not been successful anywhere. Decentralized waste management requires communities to process waste in their own locality using low-cost mechanisms.
Placing water and wastewater treatment right where it’s needed is becoming more and more viable as technology evolves.
In water management, there are two main ways to plan water and wastewater treatment systems:
⦁ Centralized treatment, which is characterized by large-scale plants that serve expansive municipal or regional service areas.
⦁ Decentralized treatment, which uses smaller plants placed close to the water supply or treatment need, serving a more localized area.
Both strategies have their strengths, but new technology, engineering, and financing structures are rapidly making decentralization a preferred strategy in a growing list of scenarios.
Large-scale, centralized desalination or wastewater treatment plants, which use widespread collection and distribution networks, leverage economies of scale to treat water at a low price point, but there are many tradeoffs.
For example, the Ras Al-Khair desalination plant in Saudi Arabia produces 728 ML/d of potable water for the residents of the capital city of Riyadh, but the price of building the plant was $7.2 billion.
On the other hand, more isolated communities and industrial installations can benefit from decentralized wastewater treatment and desalination, which brings right-sized treatment to where it’s needed, with much lower set up costs. Once built, decentralized can match centralized treatment’s water price points and quality.
For instance, at the Reserva Conchal resort in the remote coastal jungle of Costa Rica, an unobtrusive, small-footprint decentralized desalination plant supplies the water needs of the resort.
The model also works in industrial settings. On-site decentralized water treatment can provide quality control, enable water reuse, keep utility bills down, and preserve vital goodwill in the surrounding community by cutting withdrawals from local water supplies.
While modular treatment units designed for decentralization can’t take advantage of economies of scale, they instead use the assembly line concept to limit costs.
Size Versus Agility and Resilience
Large-scale infrastructure can deliver massive capacity, but it’s less scalable and less resilient. Sydney, Australia’s Kurnell desalination plant can produce 250 ML/d of desalinated water. It was built to counter a severe drought that lasted eight years.
But it took eight years and AU$2 billion to build, and came online just as the drought lifted. It was shut down as soon as it came online.
In contrast, the 200-home neighborhood of Bordeaux on St. Thomas in the Virgin Islands has been served in recent years by a decentralized wastewater treatment plant featuring membrane aerated biofilm reactor (MABR) technology. After a devastating hurricane struck, it was months before the island’s centralized wastewater treatment facility could be restarted, but Bordeaux’s MABR-based plant was fully operational only hours after it was restarted on a generator.
Decentralized systems featuring such modular units can be scaled up or down to respond quickly to changing needs. The units can be strategically moved or sold, or easily scaled up by adding more units.
Decentralized projects also tend to sidestep a mire of complex planning and negotiations across jurisdictions. Decentralized solutions avoid situations like California’s proposed centralized Poseidon desalination plant, which after two decades, is still mired in the planning stages without ever breaking ground.
Capital and Operating Expenditures
A significant benefit of decentralized treatment is its cost savings, particularly in terms of collection and distribution networks, which can account for 75% of the capital expenditure (CAPEX) when establishing wastewater treatment plants.
Long pipelines to outlying areas may encounter construction delays over rugged terrain, sensitive endangered species habitat, archaeological finds, and a host of unforeseen obstacles that can push construction over budget.
Pipeline operating expenditure (OPEX) is another consideration. It includes running and maintaining electric pumping stations to move water or effluent, and the cost can grow as equipment ages.
