Total nitrogen meets the standard and reduces the cost? You must know these optimization methods!


Whether it is the "Notice on Further Regulating the Environmental Management of Urban (Park) Wastewater Treatment" issued by the Ministry of Ecology and Environment in December 2020, the "Administrative Measures for Ecological Environment Standards" issued in January 2021, or the "14th Five-Year Plan" The green development that China clearly insists on promotes fully shows that my country is paying more and more attention to environmental issues.

Among them, sewage treatment is the key development direction of the environmental protection industry, and as an extremely important item of various monitoring indicators for sewage discharge, more and more industrial sewage have requirements for total nitrogen discharge standards, and the standards are gradually increasing.

As we all know, because biological treatment is more cost-effective than physical and chemical methods, the most commonly used denitrification processes in China are still based on microbial water treatment technologies, such as AAO, SBR, CASS, biological filters, and so on. However, despite this, processing costs can still be reduced through a series of technical means.

Cost reduction optimization method

Common cost reduction methods are mainly reflected in the aspects of process and equipment optimization, sludge treatment, and pharmaceutical management:

· 1. Process and equipment optimization ·

In terms of technology, it is mainly based on factors such as upstream industry, geographical topography, economic level, population distribution, climatic conditions and regional environmental capacity to select the appropriate treatment process, or to optimize the system by changing the process parameters; in terms of equipment, choose the cost-saving Equipment, such as the use of magnetic levitation fans to save power consumption, the use of automatic dosing devices to effectively control the dosage of chemicals (carbon sources), etc.; due to the high cost of one-time input due to process and equipment optimization, it is restricted by conditions such as site area and existing facilities. It is more difficult to renovate an already running water plant, and the actual cost reduction optimization in this area is mostly based on parameter adjustment.

· 2. Sludge treatment ·

Sludge treatment is a major stage of electricity consumption, accounting for about 50% of the total power consumption of the water plant. At the same time, the cost of sludge disposal is also high (mainly incineration, for example, the cost of treating sludge in a brick factory is about 280 yuan/t ), generally by improving the working efficiency of the dehydrator, replacing the medicament that reduces the growth of sludge, etc., the cost reduction work in this area is carried out.

· 3. Pharmaceutical management ·

Use more cost-effective agents (carbon sources), add appropriate nitrification/denitrification bacteria, etc., to reduce the cost of chemical dosing, labor and equipment operation (maintenance).

Examples of cost reduction for nitrogen removal optimization:

Project Overview

Water plant goal: reduce the cost of carbon source by 10%.

A water purification plant in Guangdong is designed to treat 24wt/d of water, and the actual treated water is about 20wt/d; the main process on site adopts the "improved A2O+ denitrification filter + magnetic coagulation sedimentation" process; the total influent nitrogen is 35-40mg/ L, influent ammonia nitrogen 20-30m/L, influent COD 300-400mg/L; effluent total nitrogen 4-9mg/L, reaching the standard (10mg/L); carbon source (sodium acetate) dosage 35t/d.

problem analysis

The water plant mainly conducts denitrification and denitrification by adding sodium acetate to the denitrification filter. This method has two problems:

1. Because the COD equivalent of sodium acetate is relatively low, only 18-20wmg/L, this leads to a huge amount of carbon source on site (35t/d), which leads to manpower, power consumption, carbon source addition, storage, transportation, etc. The overall cost is high.

2. Since the denitrification and denitrification process is centralized in the denitrification filter, the total nitrogen of the effluent is very susceptible to the influence of the influent water quality, water volume, etc., which may cause large fluctuations.

Cost reduction program

Through small-scale verification and technical exchanges, the Kubaru total nitrogen team proposed a technical solution for adding Kubaru composite carbon source to the improved A2O biochemical section, so as to remove total nitrogen by making full use of the front-end A2O biochemical section to remove the total nitrogen. The end denitrification filter is used as an emergency standby denitrification stage to optimize the biological denitrification process of the water plant, thereby reducing the treatment cost of total nitrogen removal in the water plant.

According to the on-site process conditions, the composite carbon source dosing point is set at the front end of the backflow in the anoxic tank section. The technical team of the entire pilot test process is mainly based on the on-site online monitoring of the real-time update data of the influent nitrate nitrogen of the denitrification filter and the use of The data obtained from the regular and fixed-point detection of the gram-quick detector, comprehensively analyze and adjust the amount of carbon source dosing; meanwhile, provide professional technical training and guidance for water plant operators.

Optimization effect

1. Before the pilot test, the influent nitrate nitrogen of the filter basically fluctuates in the range of 10-12mg/L. After adding the Kubalu composite carbon source, the nitrate nitrogen of the filter influent can be stabilized below 8mg/L.

2. The optimal dosage of the Kubaru composite carbon source is 14-15 tons; the dosage of sodium acetate is controlled below 5t/d to maintain the activity of the filter and provide emergency protection, and the total nitrogen in the effluent is basically low At 7mg/L, the amount of sodium acetate can still be further reduced.

The Kubaru Total Nitrogen In-situ Compliance Technology uses a composite carbon source that has a good effect on denitrification and denitrification in the anoxic section, and successfully makes full use of the front-end biochemical process of the water plant, making the back-end denitrification filter an emergency standby stage. The amount of sodium acetate added is greatly reduced. This not only reduces the overall cost of carbon sources by more than 14%, but also keeps the total nitrogen in the effluent in a safer range, and further improves the system's impact resistance to fluctuations in influent water quality and water volume.