What’s the best wastewater treatment system by industrial sector?

On our blog, my colleagues and I often talk about how dangerous the textile sector can be to the preservation of the world’s water resources. But there are many sectors that require significant amounts of water for their production processes, and perhaps we don’t mention them enough. In fact, the main industrial water use applications include the food industry, mineral and oil refineries, and hydroelectric dams. In these processes, water can play the role of cooling, solvent and chemical reagent.

For these companies, the delicate relationship and dependence on this resource translates into responsibility. Indeed, the residual water from industrial processes cannot be thrown into the environment because of the danger of contamination, so it will have to be treated with appropriate systems before being discharged outside, or at best reused within their own production cycle.

Let’s take a look at the sectors that use the largest amounts of water, but more importantly let’s see what technologies can come to the rescue of the companies that operate in them.

FOCUS

Wastewater recovery in the textile industry

The textile sector was the third largest source of water degradation and land use in 2020, requiring an average of nine cubic meters of water to provide clothes and shoes for each EU citizen alone.

Textile production is estimated to be responsible for about 20 percent of global clean water pollution from dyeing and finishing products, discharging more than 700,000 microplastic fibers after only the first wash.

One of the greatest innovations in textile water reclamation since the late 1990s has been to employ a fully biological system, based on the activity of bacteria, which allows, if designed properly, a 90% abatement of chemical-type pollution through a process of oxidation, or rather decomposition.

To date, this technology is one of the most popular with large Western buyers. The use of chemicals is almost absent, which is why in general operating costs are among the lowest ever, produce very little non-toxic sludge, which in some countries can be used as fertilizer in agriculture. Thus, organic technology emerges as a sustainable solution that enables full compliance with international ZDHC regulations, which often overlap with local regulations in individual countries.
The textile sector, among those with the highest vocation for sustainability, has been aiming in recent years for total water recovery, the so-called Zero Liquid Discharge, and aspires to 100% water reuse within the textile process itself.
This is possible with Reverse Osmosis systems, designed involving up to 5 passes, to achieve 97-98% wastewater recovery.

FOCUS

Wastewater recovery in the food sector

One sector that we mention little, but which is important to remember, is definitely the food sector. The large amount of water required for food production means that water resources are predominantly allocated to the agricultural sector. In low-income countries, water use in agriculture accounts for 90 percent of all water withdrawals. This figure is significantly lower in high-income countries (44 percent), where a larger share of water is allocated to the industrial sector.
In fact, most of us do not consider the water footprint in the production of our food. But food production depends on water: an estimated 70 percent of all freshwater extracted is used for agriculture alone. Another 20 percent is used in production and processing industries, leaving only 10 percent for domestic use.

Thus, single-stage or dual-stage biological treatment is also used extensively in the food sector, which in some cases may need to be preceded by a flotation plant for the purpose of removing fats and oils in the water.
This would allow the biological system to perform better, and the mechanical equipment to function better.

WHY IS OIL A WATER POLLUTANT?
Spent oil creates a superficial film that prevents water oxygenation and compromises the existence of flora and fauna. In addition, waste oil hinders deep penetration of sunlight, drastically damaging the marine environment and water life.

FOCUS

Wastewater recovery in the metallurgical sector

Water filtration in the metallurgical sector is critical, as it must ensure the quality of production processes and protect the surrounding environment. This sector uses large amounts of water in multiple stages of the metal production and processes, including cooling, cleaning and transportation.

Treatments can be varied, depending on the specific process. Typically one need to remove coarser solids, so a scale pit, a treatment system for oil removal, a biological plant for COD (Chemical Oxygen Demand) removal, but also multimedia filtration systems for removal of suspended solids, water cooling systems with evaporative towers may be needed. In short, it depends on the stage of processing. Through reverse osmosis, treatment plants can reuse water within their cycle by forming a closed loop. Purging will then be required to keep the salinity under control, which will then be replenished with a make-up system.

WHAT ARE THE PROBLEMS RELATED TO SALINITY?
Direct contact with waters rich in salts (especially sodium but also potassium, magnesium, etc.) negatively affects microflora and microfauna, which are essential for the proper physical and chemical evolution of the soil (remember texture and humification processes). What’s more, it inhibits root osmotic exchange, which is the means employed by plants to absorb water and the nutrients dissolved in it.

CONCLUSIONS

Why industries need to recover industrial wastewater?

Industrial water consumption accounts for about 27 percent of global water consumption. Many industries require large amounts of water to run the production cycle, so companies are also called upon to invest in reducing their water consumption. Water availability is also being put at risk by climate change. It is estimated that for every degree increase in the earth’s temperature, water resources are reduced by 20 percent.

To fight this problem together, it is important to ration global water demand, with incentives for saving and sustainable sources, but also to take advantage of wastewater, properly recovered.

There are many companies specializing in industrial wastewater recovery that can provide you with the right support in incorporating the best industrial technologies for all stages of production in your business. Invest in the best professionals-it will result in savings for you and gains for the world’s water resources.