What are biosolids?

Biosolids are the nutrient-rich organic product of wastewater treatment. During the wastewater treatment process, the liquid portion of the wastewater is treated and returned to rivers or lakes, and the solids, or ‘sludge’, are further processed into stable organic material, called biosolids. Everyone contributes directly or indirectly to biosolids, whether connected to sewer systems or on septic tanks. It is therefore important for households and businesses to properly dispose of hazardous materials at waste collection facilities and not into a sewer or septic system. 

Where does dirty water go?


When the wastewater flushed from your toilet, drained from your household sinks, washing machine, or dishwasher leaves your home, it flows into your septic system or your community’s wastewater treatment facility.

When septic tanks are pumped out, the waste may be disposed of through land application (spreading any chemicals or heavy metals that are in the waste onto the fields as well), taken to the local wastewater treatment facility, or taken to a solid waste incinerator for disposal.

Your home may be connected to a wastewater treatment facility. The wastewater from homes, along with the wastewater from some septic

haulers, businesses, industries and other facilities, is treated to reduce or remove pollutants.

How is the water at a waste water treatment plant treated?

Waste water treatment plants incorporate a series of processes to try to remove pollutants from water used in homes, small businesses, industries, and other facilities. All wastewater goes through a primary treatment process, which involves screening and settling out large particles. During treatment, solid, semi-solid, and liquid residues, or sludges/ biosolids, are removed from the wastewater. Sludges/ biosolids may be composted, land applied, incinerated, or landfilled.

The wastewater then moves on to the secondary treatment process where organic matter is removed by allowing bacteria to break down the pollutants.

The treated wastewater is then usually disinfected with chlorine to remove the remaining bacteria.

Some communities go one step further and put the wastewater through an advanced treatment process to reduce the level of pollutants of special concern to the local waterbody, such as nitrogen or phosphorus.

What happens to the treated water when it leaves the wastewater treatment plant?

The treated wastewater may be released into local waterways where it is used again for any number of purposes, such as supplying drinking water, irrigating crops, and sustaining aquatic life.

What Can You Do to Protect Local Waterways and the Environment?

FLUSH RESPONSIBLY! Don’t pour household products such as cleansers, beauty products, medicine, auto fluids, paint, and lawn care products down the drain. Properly dispose of them at the HHW events.

Wastewater treatment facilities are designed to treat organic materials, not hazardous chemicals. If you pour chemicals down the drain, they might end up in your local rivers or lakes or spread on land.

Don’t pour used motor oil down the drain.

Used motor oil can diminish the effectiveness of the treatment process, and might allow contaminants to be discharged. The contaminants could pollute local waterways or harm aquatic life.

You Don’t Have to Use Toxic Products! Make the Switch…and here’s why

human cancer caused by exposure to toxins (Source EPA)
toxic cleaners used by average American annually

Choosing Wisely

Adopt a new way of thinking about hazardous household products. Try to buy less or use non-hazardous products as much as possible. The best way to tell if a product is hazardous is to read the label.

DANGER indicates the product is extremely hazardous: a taste could be fatal. WARNING and CAUTION signal a somewhat lesser hazard. Select products with a CAUTION label over those with WARNING or DANGER. The best selection is one with no hazards.

Plan Ahead: Now that you know the possible dangers of disposing of HHW improperly, try to identify any products you may have that need to be disposed of properly.