With the continuous improvement of farmers'economic income and the change of their lifestyle, sanitary wares, washing machines and bathing facilities have entered ordinary people's homes, which makes the per capita water consumption and sewage discharge in rural areas increase continuously. Most of these wastewater is directly discharged into the environment without treatment or simple treatment, which not only has a negative impact on the water environment quality of the surrounding watershed, but also gradually poses a threat to human health. Mobile Bed Biofilm Reactor (MBBR) - Ion Exchange Phosphorus Removal Process is a new combined process for rural domestic sewage treatment. This paper introduces the characteristics and advantages of this process in the treatment of rural domestic sewage, and illustrates it with practical engineering cases.
Summary of Rural Domestic Sewage
1. Sources and main pollutants of rural domestic sewage
Rural domestic sewage refers to the sewage produced in the life of rural residents, mainly including toilet flushing sewage, kitchen sewage, washing and bathing sewage, in addition, it also includes some sewage produced in the process of decentralized farming in rural areas. The results show that the main pollutants in domestic sewage are organic matter, nitrogen and phosphorus. Among them, kitchen sewage and toilet flushing sewage are the main sources of organic matter, toilet flushing sewage is the main source of nitrogen, washing and bathing sewage is the main source of phosphorus.
2. Characteristics of Rural Domestic Sewage
The discharge of rural domestic sewage varies greatly and the discharge is uneven. Generally speaking, the discharge of domestic sewage in rural areas has three peaks in one day: early, mid and late, while the discharge of domestic sewage from midnight to early morning is rarely or even breaks.
In addition, the quality of rural domestic sewage is closely related to residents'living habits and local customs. The contents of BOD, nitrogen and phosphorus vary widely, but the quality of rural domestic sewage is not very poor, and it has good biodegradability, and contains almost no toxic and harmful organic pollutants and heavy metal ions.
II. Analysis of Moving Bed Biofilm Reactor (MBBR) - Ion Exchange Phosphorus Removal Process
1. Principles of Process Selection
Because the rural economy of our country is less developed than that of the city, it is difficult to equip professional sewage treatment and operation managers, so we can not copy the over-complicated municipal sewage treatment technology to the rural areas. At the same time, considering the residential characteristics of rural population and the characteristics of domestic sewage, the following basic principles should be taken into account when selecting rural sewage treatment technology: high automation, simple operation and late maintenance management; strong anti-impact load capacity, the treated sewage can meet the discharge standards; minimizing sludge production or basically no sludge production; giving priority to "moderate concentration place"; The mode of "rationalization" can reduce the construction and operation costs.
2. Advantages and Disadvantages of MBBR in Rural Domestic Sewage Treatment
(1) Process Advantage Analysis
Firstly, compared with A2/0 and MBR process, MBBR operation is simple, without debugging complex process parameters, and later operation and maintenance is convenient.
At the same time, MBBR high-performance filler enriched a large number of active microorganisms, increased the amount of activated sludge, increased load resistance, enhanced sewage treatment capacity, even if there is no water in a short time, its internal ecological environment can make the active microorganisms remain dormant, and once re-inflow, the recovery rate of active microorganisms is much faster than that of ordinary suspended microorganisms, which is suitable. Rural domestic sewage is characterized by large variation in water volume and uneven discharge.
In addition, MBBR is a micro-power and low energy consumption process in rural domestic sewage treatment process. In the aeration process, the friction and shear between high performance fillers can make the bubble smaller, increase the utilization rate of oxygen, improve the aeration efficiency and reduce the energy consumption of aeration. On the other hand, in the process of rural domestic sewage treatment with a small amount of daily treatment, the MBBR process aerator can completely use the electromagnetic blower with large air volume, low energy consumption and low noise to minimize energy consumption and interference to the surrounding environment.
Finally, the characteristics of MBBR process can make it run under high volume load and low sludge load, and the production of excess sludge is low or no excess sludge can be discharged for a long time. Therefore, the sludge production is greatly reduced, which is suitable for the basic situation in rural areas and reduces the cost of sludge treatment.
(2) Process disadvantage analysis
Compared with A2/0 and MBR, the only disadvantage of MBBR process in rural domestic sewage treatment is that it can not effectively ensure the removal of phosphorus elements, especially in the case of high phosphorus content in influent and low phosphorus content in effluent. Because the removal of phosphorus in biological process relies on the discharge of excess sludge, and in order to achieve sludge reduction to adapt to the basic situation of rural areas, MBBR process does not discharge sludge or only discharges inactivated sludge from high-performance fillers once in a long time, which makes phosphorus removal become a disadvantage of MBBR process.
3. Advantages of ion exchange phosphorus removal process
At present, the main processes of phosphorus removal in water include biological phosphorus removal, chemical phosphorus removal, constructed wetland phosphorus removal, ion exchange phosphorus removal and electrochemical phosphorus removal.
By comparing the advantages and disadvantages of different phosphorus removal technologies, ion exchange phosphorus removal technology is selected as the supplementary phosphorus removal process of MBBR to form the enhanced phosphorus removal process for rural domestic sewage. The main reasons are as follows: ion exchange phosphorus removal technology has stable effluent, simple operation, no sludge production; ion exchange resin can be recycled and reused, and long-term operation can reduce costs.
4. Phosphorus Removal by MBBR-Ion Exchange
MBBR-ion exchange phosphorus removal process is divided into four steps
In the first step, domestic sewage is first homogenized in the regulating tank and then entered into the anaerobic zone by the lifting pump.
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