title: A novel biosensor for the rapid determination of biochemical oxygen demand.
abstract: OBJECTIVE
  To investigate the function of a novel biosensor used for the rapid determination of biochemical oxygen demand (BOD) which is developed by our research group based on suspended immobilized microbial cell system in a completely mixed determining chamber as a substitute of the traditional membrane system.
  
  
  METHODS
  Activated sludge was immobilized by PVA gel and used as a bio-sensing element. The novel biosensor was used to measure the short time BOD value and the conventional cultivation method was used for BOD5 measurement.
  
  
  RESULTS
  A linear relationship was observed for the difference between the current and the concentration of glucose-glutamic acid (GGA) solution below 200 mg/L with a correlation coefficient of 0.995. The optimal response of the sensor was obtained at pH 7.0 and 30 degrees C. The sensor response was within 15 min and was reproducible within +/- 5% of the mean in a series of eight samples containing 75 mg/L BOD using standard GGA solution. The novel sensor response was found to be fairly constant over a period of 30 days, with +/- 5% fluctuations.
  
  
  CONCLUSIONS
  A relatively good agreement is found between BOD estimated by the novel BOD biosensor and that determined by the conventional 5-day BOD method. This novel BOD biosensor has good sensitivity, stability and reproducibility.
authors: Laboratory of Environmental Technology, INET Tsinghua University, Beijing, China.
authors: Jin-Song
authors: JS
authors: Chen
authors: Li-Sheng
authors: LS
authors: Zhang
authors: Jian-Long
authors: JL
authors: Wang
mesh_terms: D015374:Biosensing Techniques; D001888:Boric Acids / Q000737:chemistry; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D010100:Oxygen / Q000032:analysis* / Q000378:metabolism; D011142:Polyvinyl Alcohol / Q000737:chemistry; D015203:Reproducibility of Results; D012722:Sewage / Q000382:microbiology; D013696:Temperature
chemical_list: D001888:Boric Acids; D012722:Sewage; D018698:Glutamic Acid; D011142:Polyvinyl Alcohol; D005947:Glucose; C032688:boric acid; D010100:Oxygen