By N. S. Venkataraman

Mr. Nitin Gadkari, the Minister for Road Transport & Highways, Government of India, has said that urine banks should be set up in every taluk in India, so that urine can be collected from individual citizens and processed to produce urea fertilizer. According to the minister, this will be a step towards minimizing the import of urea in India.

The minister said that farmers will be expected to collect the urine in 10 litre plastic cans provided by the government and bring them to taluk centre, for which the farmer would get Rs. 1 per litre. Synthetically produced urea fertilizer has 45% nitrogen content.

Human urine has nitrogen content and this is why the minister has been tempted to plan to use of urine as replacement for synthetic urea fertilizer. Synthetic urea projects of economic capacity from natural gas have now been set up in India with an investment of around Rs. 5000 crore each. India is now one of the largest importers of urea fertilizer in the world.

Since the statement has come from the minister in his official capacity, it is deemed to be considered to reflect the fertilizer policy planning measure of government of India.

On reading the minister’s statement, many would wonder as to whether reducing the import of urea is a task as simple as this.

Of course, those who think that India is not adequately utilizing its large population of several millions of people and whose number are increasing at alarming rate would be thrilled at the above idea of the minister for finding a way to use the Indian population potential as an economic source. Those who have been saying that huge population of India is a blessing in disguise will applaud the minister for acting as strong advocate of their cause to use human beings for productive purpose.

Import level of urea fertilizer

Urea is the richest source of nitrogen among the common dry fertilizers and is the most commonly used fertilizer in India.

In the year 2015-16, India imported 8.4 million tonne of urea, valued at Rs.15,643 crore

Urine as source of urea

Urine consists of approximately 98 percent water and 2 percent urea, which is made up of carbon, oxygen, nitrogen and hydrogen atoms.

In fresh undiluted human urine, the concentration of the following constituents in urine may be regarded as a careful approximation:

Urea: 9.3 gram per litre

Creatinine: 0.670 gram per litre

Sodium: 1.17 gram per litre

Potassium: 0.750 gram per litre

Chloride: 1.87 gram per litre

Conversion of urine to urea

The process involves three major steps

Collection and storage

Urine makes up less than around 0.5 % of household wastewater. At community level and (urban) large-scale (where the risk for cross-contamination is high), urine needs to by hygienised before reuse.

Storage is a necessary step in the process of urine reuse, either directly after production or before central collection and treatment. Thus, several parameters must be taken into account.

Extended storage is the simplest, cheapest and most common method to treat urine with the aim of pathogen kill and nutrients recovery. Pathogen removal is achieved by a combination of the rise in pH and ammonium concentrations, high temperature and time. However, the costs for land and storage tanks can be significant.

Recommended storage time at temperatures varies between 4 to 20 deg C and one to six months respectively, for large-scale systems depending on the risk for cross-contamination (e.g. user habits, maintenance) and the type of crop to be fertilized.

Pasteurization

The primary aim of this treatment stage is to eliminate the pathogens present in urine such as viruses, bacteria and protozoa. Secondly, as temperature strongly influences enzymatic activity, pasteurization could be a solution to inhibit urease activity, if operating at the right temperature.

Failure to deactivate urease in the pasteurisation stage of prototype would result in large quantities of ammonia being produced, putting the operator at risk

Evaporation

In order to produce an effective fertiliser, the nutrients in urine need to be concentrated through an appropriate volume reduction technique.

Concentrating urine is also the best response to the problems of transportation and storage associated with the use of urine as a liquid fertiliser.

Risks of urea from urine

As human urine contains ~98% water, it can be expensive to transport and store

The nitrogen in stored urine is in the form of ammonia, which is prone to evaporation and requires special handling during storage and handling

No established process technology and operating plant anywhere in the world.

Social taboo associated with handling and using urine based urea in production of food crops.

Mode of application as fertilizer

After storage or pasteurisation has eliminated pathogens, there is a chance of recontamination, leading to the advice that urine should only ever be spread on the soil rather than edible parts of the plants.

Urine application has been shown to increase the electrical conductivity of the soil, which, depending on the levels applied, can have an adverse effect on the crop

Other risks to consider are prevalence of heavy metals in urine although these are low compared with other organic fertilizer.

Research Efforts

Research Institutions are now conducting research to examine the safety and efficacy of using urine derived fertilizers in agriculture. Research efforts are only in the development stage.

Is it a feasible or a ridiculous idea?

The proposal of the minister to use urine as urea fertilizer is likely to receive derisive laughter not only from lay man but even from technologists.

Many persons would call it as ridiculous idea and may even be tempted to criticize Modi government for advancing such suggestions.. Any idea is worthwhile, only if it can be implemented in a smooth way and would make economic sense in a commercial facility. These aspects have not been studied carefully yet.

Urine to urea project is yet to be validated scientifically from the point of view of productivity and utility factors.

Minister should have exercised some caution before airing his views in public, making everyone think it is a policy measure of Modi government. The minister should have ordered some specific research efforts and feasibility studies and thrown the results for public debate before announcing this measure.

It often happens that a vague, careless suggestion of a minister without sustained study, deflect from the public attention otherwise excellent work of the government and particular minister.