Case Study: Managing wastewater and minimizing treatment fees

BIOX1010

A yogurt plant was faced with the challenge to prevent BOD shocks to a local municipal treatment plant. The wash water and accidental releases from the yogurt plant are laden with organic matter such as milk proteins, sugars, fats, fruit and flavoring agents all yielding high BOD. The high BOD loading had caused major upsets at the treatment plant resulting in large fines and surcharges to the company. When the yogurt plant added a new production line it was concluded by the treatment plant that the additional flow from the plant would be acceptable but BOD shocks must be avoided.

The plant's existing BOD determination method utilized a time profile of the plants effluent established by collecting and assaying samples every two hours over a 24 hour period for several years.  Additional samples were collected as composites and assayed providing the plant with a daily BOD value. Since the standard laboratory method requires five days¹ to produce a BOD result, it was impossible to identify and inform the treatment plant of a high BOD excursion in time for them to make an informed decision to divert the high strength stream.

Several online monitoring technologies were explored to address the situation in real time. The following online technologies were considered; COD (Chemical Oxygen Demand), TOC (Total Organic Carbon), optical (UV254) and BOD. After evaluation and weighing the pros and cons of each technology and monitoring system, it was concluded that the continuous BOD measurement provided by the BIOX1010 was the best option. All of the above mentioned technologies are available from Endress+Hauser.

The Endress+Hauser BIOX 1010 employ the same measurement principle as the 5-day BOD test.  The analyzer utilizes a live culture and measures the changes in its dissolved oxygen requirements.  Unlike the 5-day test, the BIOX1010 is a real time, truly continuous BOD measurement, capable of detecting changes in dissolved BOD in as little as 3 to 5 minutes.  Additionally, unlike the 5 day test, the biomass is populated with organisms found in the actual waste stream therefore emulating the actual conditions of the treatment plant. To protect the biomass from pH shocks, and optional bi-directional pH adjustment is available to keep the waste stream neutral. To remove particles larger than 500 um, a course particle sieve is incorporated into a unique, easy access fast by-pass loop is available.

As a direct result of the real time information available to the plant from the BIOX1010 BOD monitor, the yogurt plant is now able to provide early warning to the treatment plant of unintentional high strength excursions.  But the greatest benefit to the yogurt plant is that they are now able to divert their high BOD flow to holding tanks and reintroduce the high BOD waste on a timed schedule. By keeping the plant in constant compliance with their NPDES permit limit has allowed the plant to eliminate surcharges.  A second benefit to the yogurt plant is because they can now constantly monitor their BOD, they have been able to identify and reduce the sources of accidental spills which significantly contribute to product shrinkage.