Effluent Characteristics

  • Production of juice concentrates and vegetable cremogenates.
  • 2,000 m3 / day (4-5 months campaign).
  • Discharge with large fluctuations in flow and pollutant load.
  • Design made for:
  1. Maximum day flow 3,000 m3 / day
  2. COD 5,000 ppm and TSS 2,000 ppm
  3. Discharge limits: COD 125 ppm and TSS 35 ppm

Plant Characteristics

  • Physico-chemical treatment (DAF)
  • Biological treatment (sequential biological reactor)
  1. Biological 1: high load reactor with pure oxygen. Useful volume of 9,000 m3 and 3 g/l of SSLM biomass.
  2. Biological 2: low load reactor with 10 surface aerators of 22 kW. Useful volume of 9,000 m3 and 6 g/l of SSLM biomass.
  • Secondary settling

Propuesta de Trabajo

SN8 Online Respirometer

  • Initially, it was agreed to install an SN8 online respirometer with 2 sampling pumps, one in the first Homogenizer Reactor with oxygen supply and the other in the second S.B.R. Reactor.
  • The first part of the work consisted of adjusting the equipment to the particular conditions of the plant, a common aspect in the initial installation of the equipment.
  • This setting is primarily focused on fine-tuning test timers to repeatedly get results under the same conditions.


  • Flow of oxygen supplied: Nm3/day that are being supplied is obtained through the application of NIPPON.
  • AOR oxygen requirement: Nm3/day needed by the bacteria are obtained through the SN8 respirometer. The equipment provides through a respirometric test the oxygen consumption rate (OUR mg / l / h) associated with the degradation of the organic substrate. From this value and by means of the ideal gas law equation, the normalized value of Nm3 / day is obtained, which allows comparing the respirometric data with the real input data through the NIPPON system.
  • COD influent reactor 2)
  • COD efluent (reactor 3)


Supplied Oxygen (NIPPON) vs COD Reactor 2

According to the data obtained, it can be observed that the oxygen supply is not carried out as a function of the organic load that enters the reactor (Graph 1). In fact, in the last part of the graph, a decrease in the organic load can be observed (orange line) while the oxygen supply is very high (blue line), inverse of what could be the most optimal.

The COD output data also indicate that the oxygen supply is not carried out in a coordinated manner with the input COD values ​​and therefore ups and downs are visualized (Graph 2). COD red line plant efluent.

Supplied Oxygen (NIPPON) vs DQO Reactor 2 vs AOR

By adding the oxygen requirement data in the same units as the oxygen supply (NIPPON) obtained by the SN8 on-line Respirometer (yellow line) we can see how the information provided by the equipment accurately reproduce the oxygen needs due to the real load that is in the reactor at each moment (Graph 3).

This means that if we control the oxygen supply (NIPPON) through the Oxygen Requirement data (AOR yellow line) we will obtain a precise optimization of said process.


  • an average of 3,986.16 Nm3/day is being contributed to the process
  • This would mean an estimate of expenditure per year of € 133,963.93
  • by respirometry, the average required by bacteria is 1,843.09 Nm3/day
  • This would suppose an estimate of expenditure per year of € 61,068.81
  • this represents an average daily saving of € 195.51
  • and therefore an annual saving of € 71,359.70 - >>> 53% !!!!