What Biosolids Do

Before the 1970s and the Clean Water Act, thousands of American cities dumped their raw sewage directly into our nation's rivers, lakes and bays. Today, because of improved wastewater treatment and strict federal and state regulations, ISD is taking what once was thought of as unusable waste and recycling it into a useful commodity.
At ISD's technologically advanced Water Recycling Facility the nutrient rich natural byproducts of wastewater treatment - referred to as "biosolids" - are highly processed and analyzed to ensure safety before they leave the facility to be used at a local landfill as alternative daily cover.

This is a win-win situation for both ISD and for the landfill operators. Not only is this a good way for ISD to dispose of its biosolids, but it also allows the landfill operators to meet federal mandates to cover all their disposed waste at the end of each day to control odors, vectors, fires, litter and scavenging.

Biosolids can also be recycled as a nutrient rich soil amendment and in some cases are used as an alternative energy source. As ISD further explores various means of resource recovery throughout its systems, these uses may be examined.

The use of biosolids is strictly mandated by several local, state and federal agencies including the Regional Water Quality Control Board, State Water Resources Control Board, California Department of Resource Recycling and Recovery, air pollution control districts and the Environmental Protection Agency. ISD also has its own management practices that oversee the safe treatment of biosolids.

There are several major laws that regulate the treatment and use of biosolids, as well as local ordinances and permits.
For more information on biosolids see the EPA's website.

Biosolids to Energy Coalition: A Regional Approach to Sustainable Energy

In 2009, ISD joined forces with 18 other Bay Area agencies to form the Bay Area Biosolids to Energy Coalition.
The Coalition is committed to creating energy from biosolids using state-of-the art technology to generate clean and renewable energy resources of value to society and the environment.


The goals of the coalition are:
  • Convert biosolids and green waste to energy
  • Create green jobs
  • Decrease greenhouse gases
  • Help meet goals set by California Global Warming Solutions Act (AB 32), Renewable Portfolio and Bioenergy Action Plan
  • Significantly reduce truck miles needed to haul biosolids for disposal
  • Use local, sustainable supplies

ISD, in addition to joining the Coalition, will be looking at other beneficial uses for biosolids such as using them for fertilizer on our agricultural fields on Jersey Island. For more information on the Coalition check out the Bay Area Biosolids website.

ISD's Biosolids Pilot Project

Whether it is recycling wastewater, finding new ways to reuse household fats, oils and grease, or finding alternative uses for biosolids, ISD is constantly looking for innovative ways to repurpose, reuse and recycle whenever possible.
When the Water Recycling Facility opened in 2011 the district found that the least costly way to dispose of biosolids, a byproduct of the wastewater treatment process, was to use them as alternative daily cover in landfills. It was a win-win situation for the landfills and the district.

But ISD is always looking for better methods of pollution prevention, resource recovery and sustainability. The question became what else could biosolids be used for? They are a valuable resource in that they contain important nutrients for plant growth and soil fertility such as nitrogen, phosphorous and organic matter.

Potential Soil Conditioner

Science shows that these byproducts would make a great soil conditioner for some of ISD's hay fields, especially at its Oakley mainland property where the soil has become less productive over the past few years.

The slow-releasing nutrients contained in biosolids are more eco-friendly than commercial fertilizers currently used by ISD because they add organic matter to enrich depleted soils and fiber that improves the soil's ability to hold water.

Produces Better Crops

Studies have shown that application of biosolids greatly improves crop growth and yields. Biosolids produced at ISD's Water Recycling Facility meet Class B criteria as defined in Federal Regulations 40 CRF Part 503.

Three fields comprising about 31 acres on the district's mainland property used for dry farming are proposed for this biosolids pilot program. These fields were chosen as they have become less productive over the past several years and incorporating biosolids into the soil is anticipated to improve crop production.

Over the next few months the district will be gathering information and setting up a pilot program for the three fields. Before any decisions are made concerning the use of biosolids on ISD property, the district will host a public information workshop on the topic.