From my old day job: thoughts on research opportunities

While I was still working, I published a paper on LinkedIn examining the possibility of converting energy-consuming activated sludge plants to possibly energy-producing anaerobic plants - which involves some significant technical issues. The paper is at: 

• “A Speculation: Convert Activated Sludge Wastewater Treatment Plants to AnMBRs?”   https://www.linkedin.com/pulse/speculation-convert-activated-sludge-wastewater-treatment-white/  
  

I came close to getting the research necessary for that underway a few times, but ran into a range of problems, so the research wasn’t done and the project never examined to see if the benefits outweighed the risks (which is not assured, no matter how much one likes an idea) - despite interest from one contractor and from overseas.

Maybe somebody will, one day, take that public paper and undertake the research necessary to see if this is viable - the sorts of energy we are considering here is around 0.5% of that of an industrialised city, although that is based on data from almost a decade ago.

My other major area of work was wastewater treatment, for which I also proposed research. 

The following brief notes (which include technical aspects) may be of interest to others in that field who are looking for a research project. 

In general, lagoon research has the major failing of not considering the effects of latitude – unlike the work by Gloyna and Bliss, which does include latitude. That has possibly been done to makes lab work simpler, more manageable, and repeatable, but it also severely limits the potential real life use of the results of that research. 

In addition, modern research fails to account for the dynamic interactions between the sludge layer and the liquor layers of lagoons. Sludge generates the inorganic forms of nutrients that algae need - meaning the atmosphere is not the only form of nutrients (influent inorganic nutrients are in low concentrations, if present at all).  

My modelling always allowed for the net accumulation of sludge (it undergoes anaerobic digestion in the sludge layer), as that reduces the active treatment volume, but this is a different effect.  

There hasn’t been any work that I consider good on that since the work by Parker, Skerry, Griggs, and Humphries at Shepperton - which was clearly flawed, as it didn’t set an upper limit on how much sludge is the upper limit (it concluded that “more sludge is better” – which is clearly absurd, as if the lagoon is full of sludge  then the influent just skates over and goes out untreated). 

The other aspect that is over-simplified is the effect of the depth of the active (treatment, or liquor - noting anoxic and anaerobic treatment is real) zone. That has to be of adequate depth to, for instance, provide adequate contact time for odorous gases released from the sludge layer (if the two main anaerobic processes are out of balance) to be oxidised.  

Now, research tends to focus on what is thought to be of interest / most potential value, or can get funding, which results in a bias towards higher tech options, and what is viewed as simpler tech, such as lagoons (although many people were surprised by the number of equations and the interactivity of my [spreadsheet] models), gets overlooked - despite the real life cost and operational advantages of that for many circumstances (especially agricultural reuse of effluent, cash-strapped water authorities, or plants in areas that cannot support the operational demands of higher tech plants). 

There is also a clear bias that leads to many people underestimating the complexity of lagoons (which is not helped by me finding that complexity easy to understand and work with - and interesting).  

There are other problems with research in the modern world around IP and ownership of data. 

Bliss was able to use data from the existing plants in the 1960s to undertake his work (and some water authorities make their data available for specific projects), but, in general, the commercialisation/privatisation of wastewater treatment has made that difficult. 

So the other option is to consider doing brand new research - such as, say ... having a series of small (field trial scale) lagoons side by side to examine issues such as: 

• the optimum depth of sludge; 

• treatment in non-aerobic liquor layers; 

• the effect of depth (including measuring gas concentrations at differing depths); 

• the effect of latitude; 

• better capture of nuance (especially around generation/capture of VSS, and capture of NVSS);

• temperature (noting that treatment of organic matter is mildly exothermic); 

• mixing/flow options (CFD does not account for the active process interactions of the sludge layer); 
  

• etc. 

And, most important of all, these would have to be continued for at least one normal sludge accumulation/desludging cycle - ideally well into the second cycle to enable comparison of new commissioning versus performance after desludging. 

 

So ... food for thought, and maybe research, perhaps.