The document stipulates that pollutant discharge indicators of chemical companies must meet the following standards: 15 mg/L of total nitrogen for petrochemical (including petroleum refining) enterprises, 25 mg/L of total nitrogen for ammonia producers, and 15 mg/L of total nitrogen for other pollutant discharge chemical companies.
Experts from the Institute of Environmental Sciences at Nanjing University who participated in the drafting of the standard told the reporter that total nitrogen is a major indicator reflecting the eutrophication of water bodies. The occurrence of water pollution incidents in Taihu Lake led the regulatory authorities to recognise the harmfulness of total nitrogen. It is of great significance to control the eutrophication of water bodies and improve water quality by mastering the total nitrogen emissions, distribution, and major sources.
Huang Huayao, director of the Xuzhou Institute of Water Treatment, told reporters that total nitrogen is the sum of nitrate nitrogen, nitrite nitrogen, ammonia nitrogen, and organic nitrogen. At present, in the sewage treatment project, chemical companies generally deal with ammonia nitrogen through nitrification and other technologies, and convert ammonia nitrogen into nitrate nitrogen and discharge it. However, practice has shown that this is just a change in the form of pollutants, and the total nitrogen content has not been reduced, so the harm to the environment remains. Therefore, the concept must be updated to include total nitrogen control as a binding indicator.
As a result, chemical companies face a new problem in the treatment of pollutants: According to Jiangsu's new standards, it is no longer enough for companies to control ammonia nitrogen as usual. In other words, the emission standards that have been counted before are now not up to the standard. For chemical companies, this impact is undoubtedly huge.
However, in an interview, the reporter found that for the total nitrogen as a control indicator of water pollutants, most chemical companies still do not understand or even heard of it, let alone pay attention to it.
When a reporter asked about the management of total nitrogen in the company, the general manager of a well-known chemical company in Sichuan used total nitrogen as another indicator of the control of water pollutants—ammonia nitrogen—to introduce the company's many measures for controlling ammonia nitrogen. With repeated reminders by reporters, the other person suddenly realized. A water treatment supervisor from a southern oil processing company that belongs to Sinopec's environmental protection star told reporters frankly that the company did not control and govern total nitrogen for the time being. He told reporters that the reason is that, with the exception of Jiangsu, the current implementation of water pollutant discharge standards has not included total nitrogen as a control indicator.
However, according to the reporter, despite the fact that total nitrogen has not yet been included in the national water pollutant discharge control standards, the control of total nitrogen has attracted the attention of the relevant state departments. The “National Total Pollutant Emission Control Plan for the Period of the 11th Five-Year Plan†issued by the State Council on August 5, 2006, proposed that in the special water pollution prevention and control basins and sea specific plans established by the State, total nitrogen and other pollution should be controlled. The total amount of emissions. At the symposium on pollution prevention in Taihu, Chaohu and Dianchi held in June this year, Du Ying, deputy director of the National Development and Reform Commission, also pointed out clearly that the total discharge of pollutants in the “three lakes†basin is still increasing, especially total nitrogen and total phosphorus. Not effectively controlled.
According to sources, the inclusion of total nitrogen in the Taihu Lake area was only the beginning of control. The reporter also learned from the Environmental Protection Bureaus in Henan, Shandong, and other places that relevant departments are “under study†for the total nitrogen control index.
According to the reporter’s understanding, for this trend, some companies in the industry have already taken the lead and started to control the total nitrogen in pollutant discharge. Shandong Deqilong Chemical Industry Group is one example. Not long ago, the company put into operation a 15,000 tons/day sewage treatment plant with short-cut nitrification—front and rear denitrification technology. The ammonia ammonia and total nitrogen content were controlled for the first time in the ammonia industry. According to the person in charge of the company, in order to control the total nitrogen content, if the enterprise starts from the source during the treatment of water pollutants and considers the overall design of the process technology and equipment, it can achieve compliance without increasing investment or increasing operating costs. Otherwise, to control total nitrogen alone, invest at least a few million dollars. This has also been confirmed by water treatment experts. According to experts, the general technologies such as A/0 used by chemical companies can remove ammonia nitrogen and organic nitrogen, but nitrate nitrogen and nitrite nitrogen can only remove about 50%, and total nitrogen cannot be controlled according to standards.
On the one hand, the control of total nitrogen is being or will be included in the control standards. On the other side, chemical companies still know little or even do not know. This means that with the promulgation of the total nitrogen control standards, after these enterprises' sewage treatment facilities can easily meet the standards, they will need to carry out technological reforms to adapt to the new standards, resulting in wastage of investment, and may even cause the development of the enterprise to be blocked again.
In this regard, the industry sources said that from now on, chemical companies should be included in the treatment of total nitrogen control when new sewage treatment facilities, one step is the best choice. For enterprises that have already been put into sewage treatment facilities, they should also plan ahead for the normal operation of future production and begin to take into consideration the total nitrogen reduction facilities.
The dredge Drag Head is a steel structure that is connected to the Dredger by a Suction Pipe. Supported by the gantries and by using hydraulic winches the dredge drag head and suction pipe are let down onto the sea bottom in order to suck a mixture of water and sand.
In order to dredge in waves, the suction pipe is suspended from special davits, which operate with heave compensation to ensure that the drag head nozzles stay in contact with the sea bed. The control of mixture of water and sand is done by a so-called dredge drag head visor. The visor controls the amount of water that enters along with the sand. In some cases this visor is hydraulically controlled.
Photo of our Drag Head:
To cut the sea bed, the dredge drag head is equipped with replaceable teeth and water jet nozzles. The nozzles are placed at the front of the dredge drag head and used to cut the sand at the sea bed vertically, while the replaceable teeth are placed at the back to cut horizontally.
The drag heads contributes to lower fuel consumption by having a low drag resistance, high production by mixing highest possible ratio of slurry, sand, clay and rocks with water efficiently.
Universal Dragheads
Our universal dragheads offer a combination of high excavation capabilities for loosening the soil and optimized hydraulic properties for mixture transportation. High mixture concentrations are possible in many different kinds of soil. Concentrations are more stable even in more compact soils, where the water flap is blocked in an optimized position. Production can be optimized by controlling the contact force of the draghead to the ground through a swell compensator system.
The soil to be dredged is loosened by cutting teeth at the visor and the effect of pressure water supply through special nozzles. The visor is equipped with an adjustable water flap for the supply of additional transport water when dredging in soft grounds.
US Dragheads
Our US dragheads are particularly suitable for dredging firmly-packed and strongly-binding types of soil. Due to their modular design, the US draghead can easily be converted into a the draghead with a turbulence visor or a universal visor. The US visor is equipped with knives and ripping teeth to loosen compact soils. Pressure water is used for fluidization of the ground. The US visor has adjustable water inlets on top, allowing the supply of additional transport water in soft grounds. Wide dragheads are equipped with two independent visors, so that the whole suction area is in close contact to the ground even on uneven ground.
The US visor is equipped with knives and ripping teeth to loosen compact soils. Pressure water is used for fluidization of the ground. The US visor has adjustable water inlets on top, allowing the supply of additional transport water in soft grounds.
Active Dragheads
Our active dragheads offer the highest production rates possible, even in compact soils and at varying dredging depths. The pressure nozzles can be arranged at the visor carrier and/or at the visor itself according to customers' preferences. The hydraulic power pack can be installed on deck or as integrated part of the draghead. Various control systems are available, enabling efficient use of the active draghead. The basic version of the control system includes continuous position indicators and switches for bridge desk mounting. Advanced dredge control and automation systems automatically adjust the visor position and water flap. Visor position can be controlled, for instance, with constant position, pre-selected Grab depth or cylinder force and water flap position to suction pressure at the draghead.
Drag Head
Drag Head,Fluid Drag Head,Steel Drag Head,Welded Drag Head
Unisite Group Ltd. , http://www.unisitemarine.com