Waste-To-Energy

When a major organics processing company set out to convert high-strength industrial organic waste and food waste with dangerously high dissolved solids (exceeding 200,000 mg/l) into renewable energy, traditional anaerobic digestion methods failed. The waste was too complex, the chemistry didn’t work, and the energy potential seemed buried beneath layers of pretreatment challenges. But RETTEW saw opportunity where others saw obstacles. We designed specialized process modeling and system integration solutions that transformed the waste conversion challenge into a competitive advantage. The result was an $80 million flagship facility representing a vision for organics-to-energy transformation across the Midwest and Southern United States, the first of an initial $400+ million construction portfolio. Today, with a total nationwide investment exceeding $1 billion, this waste-to-energy solution is scaling across multiple regions, transforming what began as an engineering puzzle into an industry catalyst.

A municipal wastewater treatment facility serving a metropolitan area with stringent phosphorus discharge limits operated a traditional in-vessel composting system that produced Class A biosolids with limited economic return. RETTEW evaluated multiple alternatives and recommended a strategic transformation involving Class A advanced anaerobic digestion with sludge drying that enabled regionalization with neighboring treatment facilities, combined with a RNG resale agreement with a national utility. This approach transformed their facility into a significant asset. Today, the facility generates over $1 million in additional annual revenue while securing a $30 million capital cost offset through the Section 48 Investment Tax Credit. Through ingenuity, an $80 million construction project became more than an operational upgrade; it became a financial strategy demonstrating what engineering expertise achieves when combined with a comprehensive approach.

A municipal wastewater treatment facility’s anaerobic digestion system was producing biogas but falling short of its potential, resulting in high operational costs and inefficient waste management. But the potential was there, buried within the existing infrastructure. RETTEW’s anaerobic digestion experts guided the client through specialized permitting and comprehensive biogas system optimization. Working with the Department of Environmental Protection (DEP) to secure the permits required for municipal wastewater treatment plants to receive and regulate liquid residual waste, we transformed their system into an energy producer. Today, the advanced anaerobic digestion facility eliminates approximately 250,000 gallons of residual waste from landfills annually, while generating more than $100,000 in energy cost savings and producing up to 200 kW of electricity from municipal waste, sewage, and plant matter. The facility now generates renewable energy attributes that can be marketed to the broader business community, creating new revenue streams while advancing community sustainability goals.

During a comprehensive upgrade to their advanced treatment plant, a municipal wastewater treatment facility recognized what others had missed. Biosolids and organic waste could become energy. But integrating combined heat and power (CHP) systems into their existing operations required specialized expertise. RETTEW designed and implemented a 375 kW CHP system integrated with a preliminary treatment system for hydrogen sulfide, siloxane, and moisture removal. The technical details that separate functional systems from optimized ones made all the difference. Through expert evaluation and system integration, we incorporated heat recovery from both the engine casing and exhaust stack to maximize energy efficiency, transforming what could have been a standard biosolids treatment upgrade into a comprehensive renewable energy solution. The facility now generates substantial electrical power from municipal biosolids and organic materials while achieving Class A biosolids stabilization standards and significantly reducing operational costs.

Renewable natural gas (RNG) only creates value when it reaches market, but that is sometimes easier said than done. A landfill operator had methane production with no way to monetize it, and another facility at larger scale had a newly constructed RNG facility with no connection to distribution networks. Both faced the same fundamental infrastructure barrier. RETTEW delivered comprehensive EPC services to transform the methane into a marketable asset. For the smaller operation, we designed and constructed steel gas lines connecting the facility to local gas distribution systems, leveraging our expertise from Marcellus and Utica Shale pipeline projects. The scope included facility foundations, civil grading, and security infrastructure – everything necessary to transform methane from emissions into beneficial reuse. For the larger operation, we managed a four-mile pipeline connecting the RNG facility to a transmission line, including comprehensive design and construction of the metering and regulation station infrastructure. RETTEW evaluated multiple corridors to minimize risks, addressed landowner concerns, managed easement negotiations, and navigated challenging terrain including areas requiring horizontal directional drilling. The completed pipelines enable upgraded landfill methane to be injected into distribution systems, supporting renewable energy distribution throughout the surrounding communities.