What is the reason of COD exceeding standard in industrial wastewater treatment?

Cod, as an important indicator of water quality detection, has always been a common problem in industrial wastewater treatment, so what are the causes and treatment methods of COD exceeding the standard? Let's follow Liyuan environmental protection.

1、 Causes of COD exceeding standard

1. The reason for the excessive COD of sewage (the reason of its own production)

The production of COD in the process of enterprise production can be said to be inevitable, for example, the residual food and water body in the food factory, the reducing substance s ion and chloride ion in the chemical factory, and the electroplating wastewater are all the reasons for the excessive COD in the sewage during the pickling process.

2. The reasons for the excessive COD of sewage - (defects in water treatment process)

(1) Biochemical treatment (low water temperature): when the temperature is too low, the activity of bacteria is also low, so as to reduce the decomposition of COD.

(2) Insufficient dissolved oxygen in the water: when the dissolved oxygen in the water is not enough to meet the metabolism of bacteria, it will cause the lack of bacteria. The efficiency of wastewater COD treatment is greatly reduced

(3) The concentration of some indicators (ammonia nitrogen, heavy metal) in wastewater is too high: too high an indicator in wastewater will poison the bacteria in the biochemical tank, so that COD can not be degraded.

2、 Harm of COD wastewater

The higher the COD is, the more serious the water is polluted by organic matter. When toxic organic matter enters into water body, it will not only harm organisms such as fish, but also enrich through food chain, and then enter human body, causing chronic poisoning.

3、 Cod treatment method

1. Physical method:

In general, flocculant is added to the wastewater, and then some pollutants are treated with grating or other physical barrier tools to take away some organic matters. But this method basically only works on COD with concentration of more than ten thousand, and it is difficult to deal with it only by this method in a few hundred times.

2. Biological method:

There are many applications in the sewage treatment plant, generally relying on a variety of bacteria, activated sludge and other biological treatment. After aerobic and anaerobic treatment, a complete treatment process is formed, which can effectively remove the soluble and colloidal biochemical organic matters. However, the adjustment of this method in the early stage will cost a lot of project investment, and the follow-up processing often needs the maintenance of technical personnel, which requires a high level of daily maintenance, so it needs to be carefully selected.

3. Chemical method:

In this way, the decomposition efficiency of organics is fast, and the treatment time is fast. Generally, the chemicals are directly added to the water outlet without too much tedious operation.