Current effective agricultural wastewater treatment technology

What is agricultural wastewater?

Agricultural wastewater is a source of wastewater produced from farmers' production activities such as animal husbandry, farming, aquaculture, and farming that contain plant protection chemicals and fertilizers. There is also some wastewater originating from food processing factories.

Agricultural wastewater seriously affects the environment.

According to statistics, thousands of kilograms of untreated fertilizers and litres of pesticides are directly discharged into the environment every year. This leads to an increased pollution of the water resources, soil and human living environment. Besides, wastewater generated from livestock farming also accounts for a relatively high number of pollutants such as suspended solids and organic lice with high BOD and COD.

Agricultural wastewater treatment technologies

To meet the need to solve the problem of agricultural wastewater, providing a safe living environment for human health. Some popular technologies are being widely applied today:

MBBR technology

MBBR is a technology for treating agricultural wastewater using aerobic microorganisms with suspended adhesive media. Specifically, aerobic microorganisms will be used combined with submerged substrates in the aerobic biological tank. In the innermost layer of the substrate surface, anaerobic microorganisms grow strongly to process macromolecular organic compounds. In the outermost layer, anoxic microorganisms thrive and will reduce nitrate into N2 to escape from the wastewater environment. The outer layer of sludge is a strain of aerobic microorganisms that increases the efficiency of treating organic matter and ammonium in wastewater. Especially the ability to handle high nitrogen - something that conventional aerobic biological tanks do not have.

MBBR technology diagram

The advantage of MBBR technology is that it is suitable for systems with small areas, simple operating procedures, and no odor. Especially the BOD and COD treatment efficiency is 1.5 - 2 times higher than normal aerobic biological tanks and good decomposition of difficult-to-decompose compounds.

AAO Technology

AAO technology, also known as A2O technology, was invented by Japanese scientists since the 20th century. Used for agricultural wastewater with BOD/COD ratio > 0.5 and high content of easily decomposable organic substances. This technology can thoroughly treat the content of nutrients N and P. With stable, easy operation and low initial investment costs, AAO technology promises to be a high-tech wastewater treatment.

In addition, two more advantages of this technology are that it is very easy to relocate to another place and that it has also a high level of automation. In order to expand the scale or to increase the wastewater treatment capacity, only additional modular modules are necessary. There is no need to remove or replace the system. Therefore, the AAO technology is very convenient and is applied by many units.

MBR biological treatment technology

MBR membrane biological treatment technology uses membrane filters with a pore size of <0.2 µm placed in an aerobic biological tank to remove microorganisms, microbial sludge, and suspended residue. Accordingly, the Aerotank gas will be continuously supplied to help microorganisms to maintain life, grow and process organic substances. Sludge and organic matter produced during this process will be retained through the biofilm mechanism.

The advantages of MBR technology are that it saves space during the construction, the wastewater retention time is short, the treatment efficiency is high, and the output wastewater will be thoroughly removed by small-sized microorganisms and sludge. However, the disadvantage is that the price is high. Consequently, it is only suitable for wastewater treatment systems with a large capacity.

Current situation of agricultural wastewater

Agricultural wastewater is currently considered as one of the main causes of serious impact on water resources. The most painful situation today is that every year there are still a lot of untreated fertilizers, plant protection drugs, pesticides, and wastewater from farming and aquaculture activities that are directly released into the environment.

According to the statistical data, the estimated amount of fertilizer used each year is about 70 thousand kilograms, but the efficiency is only about 40 – 60%. The remaining tons of fertilizer are not used but are incorporated into the soil. After that, the remaining part is washed away in surface water due to rain, and part is released into surface water sources such as lakes, rivers, streams, etc.

Current status of agricultural wastewater in rural areas

In addition, the amount of pesticides and packaging is also a serious problem when it is discharged into the environment without treatment. They do not only pollute water sources but also harden the soil, poorly retain the water, and directly affect human health negatively. About 5% of the areas are equipped with agricultural wastewater treatment using biological digesters.

In order to solve these problems, appropriate methods to treat this huge amount of wastewater are needed. Hopefully the information that FEC shares could help to make the right choice.