The NEXCITIES Project News

Preliminary Septage Analysis Conducted

Preliminary septage analysis was done this February 2021 at the De La Salle Araneta University- Agrivet Science Institute (DLSAU-AgSci). For this activity, initial tank inspection and sample collection for nutrient analysis were conducted. 


According to Engr. Regina Demalerio from the De La Salle University they try to characterize the samples before and after hydrolysis in order to determine the amount of phosphorus for struvite precipitation, the amount of ammonia and magnesium to be added during precipitation, and lastly, improve/optimize the process.


In very simple terms, she also described the process “for raw septage analysis, the samples have to be at room temperature and the solids should be allowed to settle first since it will interfere with the reading. Then we take a small volume from the sample and analyze the ammonia, nitrates, reactive phosphates, total phosphorus concentrations”


A HACH Spectrophotometer- a portable tool used for wastewater quality monitoring that uses wavelength in quantitative measurement of the material tested- was used to measure the nutrient content of the wastewater sample. The nutrients that were measured were Total and Reactive Phosphorus (P), Nitrates, Total Nitrogen (N),and Ammonia (NH3-).


Another equipment used was a Digital Reactor block which can heat samples for a process called “digestion”. Engr. Demalerio said, “digestion is carried out to break down the solids in order to release the bounded elements to the liquid medium. It is done by adding a chemical and heating the sample at a certain time and temperature. Digestion time and temperature vary depending on the parameter to be analyzed. For total phosphorus, the digestion was at 100 degrees C for 1 hour.”


Initial tank inspection at Agriventures Building
A HACH Spectrophotometer

A tour of the Laboratory

The Laboratory is where the nutrient testing and analysis happens and where the equipment for the task is kept. Surely, it is an interesting place to visit to see our scientists (and their devices) at work! As it is difficult to do an educational tour because of the pandemic, here are some of the interesting scenes from the lab: 

TNT vials used for nutrient analysis
Nutrient analysis (Total and Reactive P, Total N, Nitrates, and Ammonia)
Laboratory view

Converting wastewater into nutrient-rich fertilizer for a better city of the future