A Pepsi beverage manufacturing plant in Wisconsin suffered from high indirect wastewater discharge fees to a municipal treatment plant, mainly due to BOD content. The customer asked SUEZ if there was a way to lower these costs without the expense of building a wastewater treatment plant. The customer facility had an equalization tank and two pH neutralization tanks, providing only about 10 hours retention time before discharge.
The SUEZ service team first audited the system and documented wastewater quality over a range of operating conditions. Parameters such as BOD, temperature, pH, nutrients, oxygen and retention time were evaluated. It was decided that enhanced bacterial degradation had a good chance of reducing BOD before discharge.
The SUEZ team offered to run a trial using the SUEZ bioaugmentation/cleaner product BioPlus BA3940. This product, originally introduced for maintaining grease traps, is multi-component liquid containing bacteria, enzymes and surfactant that enhances biodegradation of food-based organics, including FOG and other related BOD. After discussion with corporate technical support, a trial plan was developed involving an initial dose of product, followed by an ongoing, lower maintenance dose fed continuously to a sump before the EQ tank. A pH neutralization target of 5.5- 6.0 was agreed upon.
For comparison, effluent discharge data was analyzed from the previous year and the average BOD on which the plant was assessed surcharges was 2149 mg/l. Data also confirmed that a minimum acceptable level of N and P nutrients were available for bacteria growth.
The baseline unfiltered BOD averaged 2149 mg/l before the BioPlus BA3940 addition began.
After 3 days of treatment, the first two at a high dose, samples of wastewater at the discharge point were collected over a three day period. The BOD averaged 1563 mg/l. This represents a reduction of 27%.
The customer decided to continue with the treatment program, as this provided a good return on their chemical investment.
Two months later sampling was again carried out (with the same chemical dosage in place). Results averaged 941 mg/l BOD. Production operations were unchanged, so the raw wastewater BOD was expected to be the same. These results showed a BOD removal of 56%. Most recently, the BOD discharge data has been averaging 1317 mg/l, representing a 39% removal over the untreated baseline.
Over the last year that this program has been in place, these BOD reductions directly translates to an average reduction in effluent surcharges of about 35%.
This simple, cost-effective bioaugmentation solution has also saved this customer significant capital investment in plant upgrades.