1、75 附录 New Wastewater Treatment Technology BAF BIOSTYR (r) Abstract Now, with the rapid economic development, but also generated a lot of social problems. One of the most serious problem is the environment. Every day a lot of solid, liquid, gas generation and emission of pollutants. Urban sewage is g
2、etting worse. Therefore, in order to improve the living environment of human beings, on the sewage treatment becomes extremely important and critical. Urban sewage treatment plant construction has become important to improve the conditions of the water environment. In recent years, advances in techn
3、ology with the sewage, wastewater treatment technology in the traditional basis, more and more new wastewater treatment technology has been extensive research development and utilization. Keywords: Water； Wastewater；Treatment Technology； Biostyr (r) 1 Introduction Sewage is created by residences, in
4、stitutions, and commercial and industrial establishments. Raw influent (sewage) includes household waste liquid from toilets, baths, showers, kitchens, sinks and so forth that is disposed of via sewers. In many areas, sewage also includes liquid waste from industry and commerce. The separation and d
5、raining of household waste into greywater and blackwater is becoming more common in the developed world, with greywater being permitted to be used for watering plants or recycled for flushing toilets. A lot of sewage also includes some surface water from roofs or hard-standing areas. Municipal waste
6、water therefore includes residential, commercial, and industrial liquid waste discharges, and may include storm water runoff. Sewage systems capable of handling storm water are known as combined systems or combined sewers. Such systems are usually avoided since they complicate and thereby reduce the
7、 efficiency of sewage treatment plants owing to their seasonality. The variability in flow also leads to often larger than necessary, and subsequently more expensive, treatment facilities. In addition, heavy storms that contribute more flows than the treatment plant can handle may 75 overwhelm the s
8、ewage treatment system, causing a spill or overflow. It is preferable to have a separate storm drain system for storm water in areas that are developed with sewer systems. As rainfall runs over the surface of roofs and the ground, it may pick up various contaminants including soil particles and othe
9、r sediment, heavy metals, organic compounds, animal waste, and oil and grease. Some jurisdictions require storm water to receive some level of treatment before being discharged directly into waterways. Examples of treatment processes used for storm water include sedimentation basins, wetlands, burie
10、d concrete vaults with various kinds of filters, and vortex separators (to remove coarse solids). 2. Process overview Sewage can be treated close to where it is created (in septic tanks, broilers or aerobic treatment systems), or collected and transported via a network of pipes and pump stations to
11、a municipal treatment plant (see sewerage and pipes and infrastructure). Sewage collection and treatment is typically subject to local, state and federal regulations and standards. Industrial sources of wastewater often require specialized treatment processes (see Industrial wastewater treatment). C
12、onventional sewage treatment may involve three stages, called primary, secondary and tertiary treatment. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. The settle
13、d and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment. Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Seco
14、ndary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment. Tertiary treatment is sometimes defined as anything more than primary and secondary treatment. Treated water is sometimes disinfected chemically or physical
15、ly (for example by lagoons and microfiltration) prior to discharge into a stream, river, bay, lagoon or wetland, or it can be used for the irrigation of a golf course, green way or park. If it is sufficiently clean, it can also be used for ground dewaters recharge or agricultural purposes. 75 2.1. P
16、re-treatment Pre-treatment removes materials that can be easily collected from the raw wastewater before they damage or clog the pumps and skimmers of primary treatment clarifiers (trash, tree limbs, leaves, etc). 2.2. Screening The influent sewage water is strained to remove all large objects carri
17、ed in the sewage stream. This is most commonly done with an automated mechanically raked bar screen in modern plants serving large populations, whilst in smaller or less modern plants a manually cleaned screen may be used. The raking action of a mechanical bar screen is typically paced according to
18、the accumulation on the bar screens and/or flow rate. The solids are collected and later disposed in a landfill or incinerated. 2.3. Grit removal Pre-treatment may include a sand or grit channel or chamber where the velocity of the incoming wastewater is carefully controlled to allow sand, grit and
19、stones to settle. 2.4. Primary treatment In the primary sedimentation stage, sewage flows through large tanks, commonly called primary clarifiers or primary sedimentation tanks. The tanks are large enough that sludge can settle and floating material such as grease and oils can rise to the surface an
20、d be skimmed off. The main purpose of the primary sedimentation stage is to produce both a generally homogeneous liquid capable of being treated biologically and a sludge that can be separately treated or processed. Primary settling tanks are usually equipped with mechanically driven scrapers that continually drive the collected sludge towards a hopper in the base of the tank from where it can be pumped to further sludge treatment stages. Grease and oil from the floating material can sometimes be recovered for specifications.
