Bioaugmentation enhances methane conversion

Problem

Methane gas production was poor at a 29 mgd (design) water pollution control plant in northern Ontario, providing primary treatment, phosphorus removal, and anaerobic digestion for 100,000 residents. The plant uses the gas to mix biosolids in four digesters and to fuel four boilers that heat the tanks and plant buildings.

Solution

Operators tested additive BCP12 from Bionetix International in Digesters 1 and 2 to boost conversion to methane-forming bacteria. The free-flowing granular powder has 5 billion microorganisms per gram along with biological nutrients and stimulants.

Result

The product increased gas production. Adding it to the four digesters during the heating season cost $25 per day, and the higher biogas volume saved the plant $200 per day in natural gas. 514/457-2914; www.bionetix-international.com

Dewatering system controls solids

Problem

When Max Conlin became general manager of the Liberty City (Texas) Water Supply Corp., the 15,000 gpd (design) activated sludge plant had not been upgraded since 1991. Treatment included a racetrack style aeration zone, an outside feed clarifier, and two 50- by 30-foot sand drying beds. Conlin tried for years to control the solids, but could not find an economic approach.

Solution

The corporation purchased a 7-cubic-yard trailer-mounted Sludge Mate dewatering container and a Poly-Mate polymer make-down system from Flo Trend Systems. The unit dewaters 7,000 gallons at a time and produces biosolids cake at 14 to 17 percent solid.

Result

The cake is hauled to the landfill, enabling Conlin to control solids production economically. 800/762-9893; www.flotrend.com

Emergency aeration eliminates sludge mat

Problem

The 0.65-acre lagoon at the Lakewood Treatment Facility in Lake Odessa, Mich., received 0.9 mgd of influent with 730 mg/L BOD and 321 mg/L TSS. Two 50 hp aspirating surface aerators failed to oxygenate the lagoon sufficiently, and it became septic. A sludge mat surfaced and became so dense that it plugged the aerators and lifted them out of the water. Operators and the plant environmental consultant searched for ways to oxygenate the lagoon and control the strong odors.

Solution

The plant purchased 12 MARS aeration systems from Triplepoint Water Technologies and installed them in two days. Each unit produces 5 to 7 pounds of oxygen per horsepower hour (lb/hp-hr) and mixes 6,585 gpm at 25 to 75 cfm airflow.

The diffusers have a central coarse-bubble tube surrounded by ten 750 mm fine-bubble tubes 12 inches above the lagoon floor. The units, installed from the surface, each sit on four weighted legs. A 50 hp Aerzen blower, throttled to 50 percent with a variable-frequency drive, supplies air.

Result

The aerators immediately began breaking apart the sludge mat and eliminated it after one day. The system uses only 25 brake hp (18.6 kW), amounting to energy savings of more than $34,000 annually. 630/208-0720; www.triplepointwater.com