Closing the loop on biosolids and algae | Without Limits

Managing Wastewater Biosolids and Harmful Algal Blooms: A Sustainable Solution

Introduction

With rising costs and increased pressure on landfilling and land application of biosolids, many utilities are evaluating alternative processes for managing such residuals. Compounding these pressures are growing concerns about excess nutrients and emerging contaminants, specifically perfluorinated compounds, i.e., PFAS. In this report, we will discuss an emerging and sustainable solution that offers exciting opportunities for beneficial transformation of wastewater biosolids and Harmful Algal Blooms (HABs) waste streams as a feedstock to produce renewable biofuel, with the added possibility for PFAS destruction.

Hydrothermal Liquefaction (HTL)

Hydrothermal Liquefaction (HTL) is a potentially game-changing technology that uses high-pressure (200 bar) and high-temperature (350°C) processes to produce a biocrude product from sludge. This process offers added benefits such as generating renewable natural gas with minimal waste, nutrient capture, and reduction of solids and chemical oxygen demand (COD) that exceed levels achieved in conventional digestion processes. The HTL process mimics the formation of fossil fuels but occurs in minutes instead of millions of years, without adding new carbon dioxide to the atmosphere.

Harmful Algal Blooms (HABs)

Harmful algal blooms (HABs) are formed by an overabundance of nutrients in water and can produce toxins that threaten human health, aquatic ecosystems, and drinking water. They are one of the most scientifically complex and economically difficult environmental issues facing the world today. HABs cost an estimated $1 billion in economic damages and losses each year in the United States alone. With continued nutrient enrichment and the effects of climate change, HABs are now occurring more frequently, becoming more toxic, and lasting longer.

Algae Harvesting Hydronucleation Flotation Technology (HFT)

At AECOM, we have developed the Algae Harvesting Hydronucleation Flotation Technology (HFT) to address the growing HAB crisis. HFT physically removes the overabundance of nutrients in waterways by harvesting algae. Algae is extremely efficient at consuming nutrients and sequestering CO₂ from the atmosphere. By removing the algae, the threat of HABs can be reduced or eliminated, and the recovered algae biomass can be used as a feedstock for the creation of biocrude via HTL. The versatility and scalability of HFT have been proven effective in numerous demonstration tests conducted in Florida, Ohio, and New York.

HTL Pilot at Altamonte Springs Water Reclamation Facility

To test the feasibility of using HTL technology to convert wastewater and wild HAB biosolids into biofuel, we set up a mobile pilot at the Altamonte Springs Water Reclamation Facility near Orlando, Florida. The pilot was supported by our strategic partner, Genifuel, using their state-of-the-art HTL technology.

Important Findings from the HTL Pilot

• The use of HTL technology to convert wastewater and wild HAB biosolids into biofuel is technically feasible.
• Wastewater treatment plants can enhance algae-to-biofuel return on investment with full-time plant operation and seasonal co-processing of harvested HABs.
• HTL shows promising potential to reduce PFAS in contaminated biosolid waste streams. With wastewater treatment plants serving as a collection point for PFAS, HTL may play an integral role in removing these persistent chemicals from biosolids.

Environmental and Societal Benefits

• The process mitigates the nutrient impacts to HAB-impaired water bodies.
• HAB harvesting reduces greenhouse gases and improves oxygen levels in the water.
• Producing energy with existing waste streams creates a sustainable circular economy.

AECOM is committed to scaling the integration of these key technologies through its continued collaboration with research, industry, OEMs, and regulatory and community partners.

SDGs, Targets, and Indicators

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 6: Clean Water and Sanitation
• SDG 7: Affordable and Clean Energy
• SDG 12: Responsible Consumption and Production
• SDG 13: Climate Action
• SDG 14: Life Below Water
• SDG 15: Life on Land

2. What specific targets under those SDGs can be identified based on the article’s content?

• SDG 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally.
• SDG 7.2: By 2030, increase substantially the share of renewable energy in the global energy mix.
• SDG 12.4: By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water and soil in order to minimize their adverse impacts on human health and the environment.
• SDG 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.
• SDG 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution.
• SDG 15.1: By 2020, ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands, mountains and drylands, in line with obligations under international agreements.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

• Indicator for SDG 6.3: Proportion of wastewater safely treated
• Indicator for SDG 7.2: Share of renewable energy in the total final energy consumption
• Indicator for SDG 12.4: Hazardous waste generated per capita and proportion of hazardous waste treated, by type of treatment
• Indicator for SDG 13.1: Number of deaths, missing persons and directly affected persons attributed to disasters per 100,000 population
• Indicator for SDG 14.1: Marine protected areas as a percentage of territorial waters
• Indicator for SDG 15.1: Forest area as a percentage of total land area

SDGs, Targets, and Indicators Table

Behold! This splendid article springs forth from the wellspring of knowledge, shaped by a wondrous proprietary AI technology that delved into a vast ocean of data, illuminating the path towards the Sustainable Development Goals. Remember that all rights are reserved by SDG Investors LLC, empowering us to champion progress together.

Source: aecom.com

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