In addition to the last post's "field"tests - remember those tests should be run within 30 minutes of collecting samples if at all possible - there are more daily tests useful for describing biomass health or activity.
MLSS/MLVSS - running the solids in the wastewater mixed liquor gives us information needed to calculate F/M and MCRT (solids residence time) in the system. Often I hear people say MLVSS = microbial population. It does NOT directly measure the microbial population. In the days before ATP or molecular testing, the only way to measure microbial populations was by plate count. Not everything grows on plate count media and it takes 24 - 48 hours to get results. So engineers substituted the use of solids testing. MLSS = the solids weight once water is removed. MLVSS = the volatile solids portion of the sludge. My main message is that while F/M and MCRT are normal control tools, they are not hard fast rules for all systems. Much variation is possible and you have to make your system work based on flows and influent makeup. Also use running averages for calculating F/M and MCRT - otherwise you will be adjusting wasting rates too often. And, never increase wasting by more than 10 - 15% in any adjustment.
Macro Nutrients (N & P) - not every system has potential for low macronutrients. However many industrial systems can have low N and/or P. In all cases you want to evaluate ASB for ammonia and ortho-phosphate residuals. As long as ammonia is 1.0 mg/L and phosphate is 0.5 mg/L you have enough residual to prevent nutrient deficiency.
COD/TOC - BOD5 testing takes five days so I like to see COD or TOC data which is usually available within 3 hours of taking samples. This can be used in calculate F/M and monitor influent quality.
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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