Innovative solutions for water, wastewater, and energy infrastructure

Your facility deserves more than just standard engineering. It deserves a partner who transforms your challenges into opportunities for efficiency, compliance, and cost savings. At RETTEW, we start with your specific needs, operational goals, and sustainability requirements. That understanding drives efficient solutions that earn the confidence of your team, community, and stakeholders.

Whether you’re operating water and wastewater treatment plants, developing anaerobic digestion facilities, producing renewable natural gas, or managing specialized industrial systems, we bring engineer-of-record expertise to your most critical infrastructure. That expertise matters most when you need it fast.

When unexpected challenges arise, you need a partner who responds immediately with solutions. From navigating complex regulatory requirements to addressing system failures to planning facility upgrades, you deserve reliable communication and strategic guidance at every stage. Your operations can’t afford downtime or delays. For more than 30 years, our team’s proven track record of proactive service means you’ll have the support you need, exactly when you need it.

Comprehensive Treatment and Biosolids Solutions

Your facility faces unique challenges that demand personalized solutions. RETTEW designs across the full spectrum of treatment technologies—from conventional water and wastewater systems to advanced biosolids management and anaerobic digestion. By understanding your existing infrastructure and operational constraints, we deliver solutions that enhance your operational performance and cost efficiency.

Biosolids-to-Energy ROI

Stop paying for disposal. Generate renewable natural gas or combined heat and power instead – and capture federal tax credits while you’re at it. Let us run the numbers for your facility.

Facility Design in practice

A growing township needed to nearly double its wastewater treatment capacity from 120,000 to 220,000 gallons per day. The catch? Meeting Chesapeake Bay nutrient limits without building a single new tank. RETTEW analyzed treatment alternatives focused on maximizing existing infrastructure and minimizing long-term costs, then recommended a membrane bioreactor system that reduced operating expenses. During design, we developed competitive procurement documents and created an automated, operator-friendly process. The real test came during construction, when we kept the plant fully operational through 560+ days of upgrades. Today, the expanded facility meets biological nutrient reduction standards, serves a growing community, and operates more efficiently than before.

A wastewater authority operated a successful composting facility that converted treatment plant sludge into Class A biosolids compost for the local community. But as the biosolids facilities reached the end of its useful life, the authority faced a choice between a simple replacement or a transformation. RETTEW evaluated Class A biosolids technologies and identified an opportunity to move beyond composting. Our design converted the existing process to state-of-the-art anaerobic digestion that transforms sludge and food waste into renewable natural gas for pipeline injection and dried biosolids. The new system includes sludge pre-thickening using belt thickeners, temperature-phased anaerobic digestion, third-party food waste processing, biogas upgrading to pipeline-quality renewable natural gas, and a thermal belt sludge dryer. The conversion delivers results that matter. Transitioning from composting to anaerobic digestion with sludge drying will save the authority approximately $11 million over the next 25 years through operational cost reductions and new revenue streams from energy production.

For nearly two decades, a regional authority has provided potable-quality reclaimed wastewater to businesses and the environment throughout their service area. As demand grew, the authority needed to upgrade their advanced water treatment facility for indirect potable reuse and year-round environmental enhancement. The critical question was whether they could expand capacity while improving efficiency. We evaluated the facility’s treatment processes, documented each system’s equipment and remaining useful life, and identified opportunities for improvement. Through annual facility reviews, we developed cost opinions and analyzed options to reduce both chemical and electric expenses. Our design delivered more than expansion. The upgraded facility doubled its output capacity from 1 million gallons per day to 2 million gallons per day of beneficial reuse water while reducing operational costs. Today, the authority meets growing demand for reclaimed water, supports environmental enhancement year-round, and operates more cost-effectively than before.

A borough authority operated a 2 mgd wastewater treatment plant with aging biosolids processing equipment. As their existing centrifuge neared the end of its useful life, they needed more than a replacement; they needed a complete biosolids processing assessment that would improve performance, cut costs, and maintain reliability as the plant scaled to design capacity. We conducted a comprehensive feasibility study evaluating sludge digestion processes to meet Class B biosolids requirements. The analysis compared mesophilic and thermophilic digestion, co-digestion, and aerobic digestion options. Simultaneously, we investigated dewatering alternatives including screw presses, belt presses, and centrifuges to replace the aging equipment. After analyzing performance, economics, and long-term viability, we determined aerobic digestion provided the most economically viable and robust sludge processing solution. The assessment delivered a clear upgrade path with confidence in both performance and value.

Strategic Planning and Regulatory Partnership

Regulatory requirements often drive your facility upgrades and improvements. Whether you’re meeting Chesapeake Bay nutrient discharge limits, managing permit renewals, addressing emerging environmental standards, or planning for future growth, you need a partner who stays ahead of regulatory changes and helps you navigate complex compliance landscapes. Rather than waiting for a crisis, RETTEW works with you to conduct comprehensive feasibility studies that examine your current operations, identify your challenges, and develop strategies aligned with your budget and objectives.

You need more than engineering design alone. Your projects require coordination across multiple disciplines, stakeholders, and phases. From financial analysis and grant identification to regulatory relations and stakeholder communication, RETTEW manages these complexities so you can focus on your operations. That means proactive coordination with agencies and disciplined project management that keeps your timeline and budget on track.

Infrastructure decisions impact your community for decades. When you partner with RETTEW, you gain informed guidance that leads to sustainable, efficient, and compliant facilities. Together we navigate challenges and align project outcomes with your mission, ensuring your infrastructure serves stakeholders well into the future.

Facility Design Specialties:

  • Act 537 Planning
  • Anaerobic Digestion (Single-Stage, Two-Stage, Thermophilic, Mesophilic)
  • Biosolids Management and Treatment
  • Biosolids Dewatering (Belt Press, Centrifuge, Screw Press)
  • Combined Heat and Power (CHP) Systems
  • Engineer of Record
  • Environmental Permitting and Compliance
  • Feasibility Studies and Strategic Planning
  • Financial Incentives and Grant Identification (Section 48E Investment Tax Credit)
  • High-Purity Water Systems
  • Hot Water and Heating System Design
  • Hydraulic Modeling and Process Optimization
  • Industrial Water and Wastewater System Design
  • Nutrient Reduction and Discharge Compliance
  • PFAS and Emerging Contaminant Treatment
  • Pretreatment Design and Evaluation
  • Pump Station and Lift Station Design
  • Rate Studies and Financial Planning
  • Renewable Natural Gas (RNG) Production, Upgrading, and Pipeline Injection
  • Sludge Drying and Solids Handling
  • Stormwater Treatment and Integration
  • Surface Water Intake Design
  • Utility Interconnection and Grid Integration
  • Wastewater Treatment Plant Design and Upgrades
  • Water Supply Treatment and Distribution System Design