Reverse osmosis purification installation

I’ll say this right away: most people think that reverse osmosis is just a membrane and a pump. In fact, operating pressure, seasonal pH fluctuations and even seal material decide more than the brand. Once in Astrakhan we had to reassemble the flanges three times because of Chinese stainless steel, which became covered with pitting corrosion within six months.

Pitfalls when selecting equipment

Nowadays everyone is chasing performance numbers, but few people are looking at stability. For example, for greenhouse farms, changes in salinity after washing the membrane can ruin the entire crop of cucumbers. We at Shandong Linyao Intelligent Agriculture Technology LLC once set up an experimental installation in the Rostov region - we had to install an additional current stabilizer, because local networks dropped the voltage to 190V.

Speaking of materials: cheap polypropylene cartridges sometimes contain plasticizers that kill the selectivity of the membrane. They checked it in the laboratory - after two months of work, the osmotic pressure dropped by 15%. Now we only use certified components, even if the customer simplifies it.

Particularly problematic is the selection of pumps. European ones can withstand changes, but the roads are under repair, and Asian ones are often not designed for our conditions. Once in the Krasnodar Territory, three pumps burned out in a month due to sand in the water - we had to install an additional cyclone filter in front of the system.

Real cases of integration with agricultural projects

Last year we did a project for a vegetable farm near Voronezh. There, the water from the well came with iron 3.2 mg/l and hardness 28 mg-eq/l. The standard scheme did not work - the membranes were overgrown within a week. I had to combine: aeration column + catalytic loading + two-stagereverse osmosis. After three months of testing, a stable 0.1 mg/l for iron was obtained.

An interesting point was discovered when working with drip irrigation. When water is too demineralized (below 50 mg/l), problems begin with the absorption of microelements. I had to develop a mixing system - now on the website https://www.lyzhihuinongye.ru there are calculations for optimal mineralization for different crops.

Another case: in the Stavropol Territory, the customer demanded the use of only domestic filters. But local production of cartridges gave a size error of 0.3-0.5 mm. I had to mill the seats for each block - this increased the installation cost by 40%. Now we always require samples before design begins.

Technical nuances that are not written about in the instructions

I regularly come across the fact that installers skimp on shut-off valves. It seems - well, a ball valve is a valve in Africa. But when, at a facility in Tatarstan, the supply line at a pressure of 12 bar was torn off due to a Chinese valve, all the automation had to be changed. Now we only use taps with Teflon seals - more expensive, but more reliable.

From experience I can say that it is better to install controllers with a reserve of channels. Once in Crimea we had to redo the control system: the customer decided to add turbidity sensors at each stage, but there were no free ports left. I had to install an additional module at my own expense.

An important point about membranes: their service life greatly depends on pre-treatment. I have seen cases where, with the same source water, some elements lasted 5 years, others - barely 2 years. It's all about the flow speed at the washing stage - if it is less than 2.5 m/s, the sediment is not completely washed out.

Features of integration with fertigation systems

When we were doing a project for Shandong Linyao Intelligent Agriculture Technology LLC in the Belgorod region, we encountered an interesting effect. When using phosphorus fertilizers and reverse osmosis water, insoluble sediment formed in the pipes. It was necessary to develop a separate application scheme - first nitrogen fertilizing, then phosphorus through separate lines.

Modern systems, such as those that we design for smart agricultural parks, require a special approach to water treatment. For example, automatic fertigation systems require water with a stable pH of 5.8-6.2. Regularreverse osmosisgives fluctuations of up to 0.5 units - you have to install buffer tanks with a CO2 dosing system.

I remember the case with a remote control system in the Lipetsk region. Conductivity sensors showed discrepancies of 30% with laboratory tests. It turned out - the influence of electromagnetic fields from frequency converters. Now we always shield the signal lines and move the sensors 1.5 meters from the power equipment.

Prospects and limitations of technology

Now many people are interested in nanofiltration, but for agriculture this is often redundant. In our projects we use hybrid solutions - where ultrafiltration can be used, we do not use reverse osmosis. For example, sorption filters are sufficient for pre-treatment of water for washing vegetables.

An interesting direction is the use of concentrate. Previously, we simply poured it into the drainage, but now we are trying to use it to control weeds. In the same Shandong Linyao Intelligent Agriculture Technology LLC, they tested a row-spacing treatment system - so far the results are encouraging, but the dosing needs to be improved.

The main problem we face is the unpreparedness of the staff. We provide three-day training, but after six months the operators start working on their own. We had to develop a system for blocking critical settings - now changes are only possible through engineering access from our server.

Practical recommendations for use

From experience I will say that it is better to change prefilters more often, but not less than once every 2 months. I’ve seen systems where the cartridges lasted for six months - then the membranes failed within 3-4 months. We now include in our contracts a mandatory replacement every 45 days for agricultural facilities.

There is a nuance with water quality control: most only measure salt content. But for predicting membrane life, the sludge density index (SDI) is more important. We install automatic SDI meters at all sites - it’s expensive, but it allows us to predict the need for chemical washing in 2-3 weeks.

And lastly, don’t skimp on washing containers. The minimum volume must be at least 15% of hourly productivity. In the Kaliningrad region they tried to reduce it to 10% - the chemicals did not have time to fully do their job, they had to carry out 2-3 washings instead of one.