Composting System Helps County Meet Recycling Mandate

The Solid Waste Authority of Palm Beach County was faced with a ban on yard trimmings disposal and the need to find an alternative to landfilling biosolids. A Florida State Legislation mandated a 30 percent organic recycling rate by 1994, so the authority sought competitive bids for a turnkey composting pilot facility.

The Solid Waste Authority of Palm Beach County was faced with a ban on yard trimmings disposal and the need to find an alternative to landfilling biosolids. A Florida State Legislation mandated a 30 percent organic recycling rate by 1994, so the authority sought competitive bids for a turnkey composting pilot facility.

U.S. Filter/CPC received the contract to design, construct and provide a fully operational IPS pilot facility.

The 30 wet ton per day (TPD) pilot facility consisted of four IPS Narrow Bay reactor vessels and one IPS compost agitator. The intent of the pilot system was to demonstrate the ability of the IPS system to handle the variety of sludges and other organic wastes generated within the county. Success with the IPS composting system led the Authority to contract and expand the pilot facility to 350 TPD, which consisted of 36 IPS reactor bays and nine IPS agitators.

The civil design and construction engineering for the full scale system was subcontracted to Beta Engineering of Rhode Island. All the process equipment, controls and performance testing was supplied by U.S. Filter/CPCs IPS group. The compost equipment controls consisted of the IPS Compmaster™ Computer Process Control System. This mechanism regulates the compost bay temperature, controls the building ventilation and odor control system, collects data, and writes reports to assist the operator meet EPA Requirements.

The facility was designed to receive ground yard trimmings and dewatered biosolids from a belt press daily. Batch mixers handle 16 cubic yards of material and weight sensors allow the operator to mix the materials on a 50:50 weight basis. The plant goal is to load all mixed biosolids and yard trimmings into the bays during the same working day.

The material is loaded at the mixing end, the compost mix is moved approximately 12 feet towards the discharge end with each agitation pass. The compost exits the bays about 14-21 days later, depending on feed stock, and is typically stockpiled for two months prior to distribution.

An important design of the full-scale facility is the biofilter system for odor control. The full-scale facility utilizes three separate 12,000-square-foot biofilters, each serving 12 reactor bays. The ventilation system maintains a negative vacuum on the building which includes floor tipping, feed stock mixing area, composting reactors and compost discharge area.

The design and construction of the new Second Nature Composting Facility was completed in a little less than a year, meeting the authority’s deadline of full-scale operation in 1994. U.S. Filter started the facility, executed and successfully passed the equipment and odor control performance tests and trained the operators prior to turning over the keys.

West Palm Beach, utilizing the patented IPS composting system, recycles up to 350 wet tons of material a day by producing beneficial odor-free compost. The compost is applied at baseball fields, new road construction, new building construction, and in a landfill closure project. The authority also is marketing a portion of it commercially and to date has been successful in beneficially recycling all the compost it produces.

In the fourth year of the WaterWorld annual Construction Survey, officials with the nation’s largest cities were asked to provide information on their projected capital improvement budgets for water and wastewater projects for the next fiscal year and the next five years. They also were asked to describe their largest projects planned for the five-year period for both water and wastewater.

More in Infrastructure Funding