Tag Archives: landfill wastewater treatment

PFAS Treatment – The Devil We Know and Need to Manage

November 25, 2019

Introduction

PFAS are a class of synthetic fluorinated chemicals used in many industrial and consumer products, including defense‐related applications. They are persistent, found at low levels in the environment, and bio‐accumulate. Studies have shown these compounds being detected more often in surface water, sediments and/or bioaccumulated into fish tissue. Because of the greater affinity of longer chain per‐ and polyfluoroalkyl substances (PFASs) compounds for fish than other environmental matrices, certain compounds are often found in fish tissue, but not in the water or sediment. Table 1 shows average concentrations of PFOA and PFOS in landfill leachates around the world. The USEPA health advisory level is 70 ppt for PFOA and PFOS.

Table 1.  Concentrations of PFAS compounds in Landfill Leachate around the world

Compound US Germany China
PFOA (ppt) 660 150 280-214,000
PFOS (ppt) 110 30 1,100-6,000

 

Treatment Options for PFOS and PFOA

The removal of PFASs from drinking water has been the USEPA’s national priority. Recent discoveries of PFAS/PFOS in drinking water in multiple states in the US has heightened interest in these emerging contaminants. Federal, state, and local agencies are formulating regulatory limits that vary greatly. These limits seem to be centered on drinking water, but these developments are driving disposal of existing stores of chemicals containing PFAS/PFOS and environmental media contaminated with PFAS/PFOS

Treatment processes that can remove PFAS chemicals from drinking water may include high-pressure membrane systems such as RO, granular activated carbon (GAC), or ion exchange as shown in Figure 1. The more conventional water treatment technologies such as (e.g., aeration) are not typically effective.

Figure 1. PFAS Removal Processes (a) Membranes, (b) GAC and (c) Ion Exchange Resins

 

Landfill Leachate RO Treatment Plant – New Hanover County, North Carolina

New Hanover County upgraded its leachate treatment system to meet stricter regulatory standards for surface water discharges, particularly standards relating to metals (arsenic) and ammonia. Sampling by NC DEQ showed the new RO plant is filtering out PFAS. Table 2 shows the results from February 2019.

Figure 2. New Hanover County Leachate and PFAS Treatment Plant

Table 2. Concentrations of PFAS compounds in Leachate at New Hanover County Landfill

PFAS Constituent Raw Treated Surface water
PFOA (ppt) 1,250 < 0.6 3.9
PFOS (ppt) 228 < 0.6 7.1

 

Comparison of GAC Types for PFOA and PFOS Removal

Four different types of GAC, i.e., Re-agglomerated Bituminous, Lignite, Enhanced Coconut and Enhanced Coconut (Blend) were evaluated under identical operating conditions and influent water quality. Figure 4 shows results from these four GAC products for PFOA/PFOS removal vs time.

Figure 4. GAC Treatability study for removal of PFOA and PFOS

Re-agglomerated bituminous coal GAC (FILTRASORB) significantly outperformed: Lignite, Enhanced Coconut and Enhanced Coconut (Blend).

Summary:

PFAS compounds are of concern because they do not break down in the environment, bioaccumulate in humans and biota, and may pose risks to human health

GAC, Synthetic adsorbent, and ion exchange resins are widely used for PFAS removal. Capacity and leakage of PFASs into the treated water varies depending on the specific PFASs, the type of adsorbent used.

PFAS removal may be influenced by pH, water temperature, contact time, Natural Organic Matter, and chlorine. For complete PFAS removal, a polishing may be required.

Disposal methods for PFAS waste streams include high-temperature incineration or landfilling. Landfilling is not favored since the PFAS load would increase, and many landfills will not accept PFAS waste.

 

About the Author:  Dr. deSilva is SCS’s Director of Wastewater Treatment. He has 30 years of progressive experience in wastewater engineering, from concept through construction and start-up, and is an international leader in operations and maintenance, energy management, solids handling processes, construction management, and commissioning wastewater treatment plants (WWTP) around the world.

Liquids Management 

 

Posted by Diane Samuels at 6:00 am
Tag Archives: landfill wastewater treatment

Waste360 Article Series – The Impacts of PFAS and a Push for Nationwide Standards

August 7, 2019

We recommend reading this article series to stay abreast of relevant knowledge from Bryan Staley, president and CEO of the Environmental Research & Education Foundation (EREF); Anne Germain, vice president of technical and regulatory affairs for the National Waste & Recycling Association (NWRA); Viraj deSilva, SCS Engineers wastewater treatment director; and testing results from New Hanover County whose capital investment in landfill infrastructure has proven to successfully treat effluent water to meet higher standards.

Read Part One

Read Part Two

 

Posted by Diane Samuels at 6:01 am
Tag Archives: landfill wastewater treatment

EREF Summit on PFAS in Leachate – August 14 – 15

August 2, 2019

This EREF Summit will bring together practicing engineers, academics, industry professionals, government personnel and policymakers to facilitate discussion and provide various perspectives on the management, issues, and policies related to PFAS.

AGENDA

Per- and polyfluoroalkyl substances (PFAS) are a group of compounds that are man-made and are commonly used in industrial processes and consumer products such as food packaging, fire-fighting foams, metal plating, outdoor gear, popcorn bags, food wrappers, facial moisturizers, mattresses, carpeting, and cookware. Despite the widespread use of PFAS in everyday products, there are still significant knowledge gaps associated with the management of these compounds.

REGISTRATION

SCS Engineers is a sponsor of this EREF Summit. Liquids Management at SCS Engineers

 

 

 

Posted by Diane Samuels at 6:03 am