8 leachate contaminant levels landfills should care about

For years, it didn’t much matter what was in your leachate. You could ship it to a publicly owned treatment works (POTW) and call it managed, regardless of the contaminants it contained.

Nowadays, that’s not a feasible way of doing business. POTWs are beholden to standards on certain contaminants and are expecting further regulations on others. Because of this, they’ve driven up treatment costs for leachate with high contaminant loads — if they accept it at all.

Ultimately, cost-effective and risk-averse leachate management requires more nuanced methods than ever before. As a starting point, it requires understanding of the contaminants making leachate more difficult to manage.

Let’s look at 8 types of contaminants that landfills care most about, as well as real-life data showing how Atmos’ alternative to traditional leachate treatment methods can remove them from your leachate.

A high-level look at the data

Below, you’ll see two tables. They display performance data of the Atmos Leachate Treatment System (ALTS) at two different landfills. Pay attention first to the contaminants measured. You’ll see that the two landfills had some different concerns.

Then you’ll see that the contaminant loads at the different landfills are significantly different. One is a highly contaminated site in the desert. The other a Gulf Coast landfill whose biggest challenge was humidity preventing evaporation.

Their ponds were filling up and their POTWs were becoming less and less viable treatment partners.

Contaminant	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
TOC	30,800 mg/L	48 mg/L	99.8
TDS	80,800 mg/L	204 mg/L	99.75
Oil/grease	13 mg/L	0 mg/L	100
PFOS	400 ppt	1.52 ppt	99.62
PFOA	1,060 ppt	Non detect	100
PFHxS	151 ppt	Non detect	100
PFNA	204 ppt	Non detect	100
PFBS	424 ppt	Non detect	100

Contaminant	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
TOC	10,000 mg/L	32 mg/L	99.7
TDS	28,000 mg/L	1,370 mg/L	95.1
TSS	390 mg/L	3.5 mg/L	99.1
Oil/grease	Non detect	Non detect	N/A
BOD	2,330 mg/L	76 mg/L	96.7
COD	40,000 mg/L	101 mg/L	99.7
PFBS	27,500 ng/L	Non detect	100
PFHxA	7,560 ng/L	Non detect	100
PFBA	1,750 ng/L	Non detect	100
PFPeA	1,810 ng/L	Non detect	100
PFOA	934 ng/L	Non detect	100
PFHxS	352 ng/L	Non detect	100

The data shows successful treatment of all contaminants, which requires a treatment system that utilizes multiple methods. Let’s dig into the contaminants themselves and their preferred treatment methods.

1. Total organic carbon (TOC)

TOC measures the concentration of carbon present in organic compounds within the leachate.

The most common TOC removal method is via adsorption filters. While the results may vary depending on the contaminant load, we can typically remove at least 99.5% of TOC from leachate with the nanofiltration module.

Landfill	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
Desert	30,800 mg/L	48 mg/L	99.8
Gulf Coast	10,000 mg/L	32 mg/L	99.7

2. Total dissolved solids (TDS)

TDS measures the combined concentration of inorganic and organic substances dissolved in the leachate. Leachate high in TDS can gunk up treatment systems that aren’t designed to filter it out and cause maintenance problems — especially in reverse osmosis (RO) systems.

The first module in the ALTS is an ultrafiltration (UF) system, designed to filter out the solids first, so they don’t cause problems in the other downstream modules. The nanofiltration and reverse osmosis modules clean up what’s left. It historically removes more than 95% of TDS from leachate.

Landfill	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
Desert	80,800 mg/L	204 mg/L	99.75
Gulf Coast	28,000 mg/L	1,370 mg/L	95.1

3. Total suspended solids (TSS)

TSS measures the concentration of solid particles suspended in leachate. Like TDS, they’ll cause maintenance trouble if not handled properly, so we treat them with a UF module.

Unlike TDS, the EPA has outlined an explicit secondary treatment standard for acceptable levels of TSS in effluent water. Treated effluent should have a 30-day average TSS content at or below 30mg/L, and treatment practices should remove at least 85% of TSS by concentration.

(Entirely biological treatment processes are granted a larger acceptable TSS concentration in effluent water).

Landfill	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
Gulf Coast	390 mg/L	3.5 mg/L	99.1

The ALTS targets TSS with its UF module and typically achieves greater than 99% TSS removal.

4. Oil and grease

This measure is more self-explanatory and covers multiple hydrocarbons like fats, oils and related substances. Oil-water separators aid hydrocarbon filtering traditionally.

The ALTS handles oil and grease by separating via mechanical screen, as well as through UF.

Landfill	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
Desert	13 mg/L	0 mg/L	100
Gulf Coast	Non detect	Non detect	N/A

5. pH

pH measures the acidity or alkalinity of your leachate. EPA standards require effluent water within a range of 6.0 – 9.0.

While the nanofiltration stage can add hardness to pH, it’s usually managed by introducing a base or acid before full treatment.

6. Biochemical oxygen demand (BOD)

BOD measures the concentration of oxygen-demanding organic pollutants in your leachate. Acceptable and unacceptable levels are determined by modeling and set by the EPA. Secondary treatment standards set acceptable concentrations at a 30-day average of 30mg/L or less. But some states have different regulations.

Whether you need to hit the federal regulations or a stricter state limit, we can customize your system to reach your BOD goals.

Landfill	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
Gulf Coast	2,330 mg/L	76 mg/L	96.7

7. Chemical oxygen demand (COD)

COD measures the concentration of oxygen-demanding organic and inorganic pollutants in your leachate. It indicates the oxygen demand placed on the natural environment where effluent water is distributed — higher levels are more likely to be harmful to aquatic life. Unlike BOD, the EPA hasn’t set a COD standard, but many states have.

Within the ALTS, the RO module filters the COD out of the leachate.

Landfill	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
Gulf Coast	40,000 mg/L	101 mg/L	99.7

8. Per- and polyfluoroalkyl substances (PFOS/PFAS/PFOA)

PFOS/PFAS/PFOA measure the presence of a suite of industrial “forever” chemicals in your leachate. They are becoming a hot topic in wastewater conversations. While the EPA recently placed limits on the acceptable amount of these chemicals in drinking water, it has not yet enacted regulations for effluent water, although some states may soon regulate PFAS in leachate.

The ALTS relies on its RO modules, as well as a final pass across activated carbon beds, to achieve removal of PFOS/PFAS/PFOA.

Landfill	Contaminant	Raw leachate	ALTS treated leachate	Contaminant reduction (%)
Desert	PFOS	400 ppt	1.52 ppt	99.62
Desert	PFOA	1,060 ppt	Non detect	100
Desert	PFHxS	151 ppt	Non detect	100
Desert	PFNA	204 ppt	Non detect	100
Desert	PFBS	424 ppt	Non detect	100
Gulf Coast	PFBS	27,500 ng/L	Non detect	100
Gulf Coast	PFHxA	7,560 ng/L	Non detect	100
Gulf Coast	PFBA	1,750 ng/L	Non detect	100
Gulf Coast	PFPeA	1,810 ng/L	Non detect	100
Gulf Coast	PFOA	934 ng/L	Non detect	100
Gulf Coast	PFHxS	352 ng/L	Non detect	100

Want to talk about the specific contaminants you’re dealing with?

We know as well as anyone that every landfill is different. If you’re running out of space for leachate ponds or emptying your pockets for offsite leachate treatment to stay within your permits, get in touch.

We can start outlining your pay-as-you-go leachate treatment system, to save you money and put some distance between your contaminant levels and your permit limits.