水看世界 EPA技术说明——分散式好氧处理

适用于农村污水处理的原位分散式污水处理系统，美国EPA提供了一系列技术说明文件，供学习参考。

原文出处：EPA

翻译：阮辰旼、王贝贝

Decentralized Systems Technology Fact Sheet Aerobic Treatment

EPA分散式污水处理系统技术概况介绍系列——好氧处理

Natural treatment of biological waste has been practiced for centuries. However, engineered aerobic biological treatment of wastewater has been practiced in the United States, on a large scale, for only a few decades. In fact, in 1925, 80 percent of all cities in the United States with populations of over 100,000 had no treatment systems at all (Linsley 1972). The basic aerobic treatment process involves providing a suitable oxygen rich environment for organisms that can reduce the organic portion of the waste into carbon dioxide and water in the presence of oxygen. With the ever increasing development of land, both suburban and rural, large central sewerage systems have not always been cost-effective or available. Many homeowners still rely on individual septic tank or other systems to treat and dispose of household wastewater onsite. Historically, aerobic treatment was not feasible on a small scale, and septic tanks were the primary treatment device, but recent technology advances make individual aerobic treatment systems efficient and affordable. Aerobic systems are similar to septic systems in that they both use natural processes to treat wastewater. But unlike septic (anaerobic) treatment, the aerobic treatment process requires oxygen. Aerobic treatment units, therefore, use a mechanism to inject and circulate air inside the treatment tank. Because aerobic systems use a higher rate process, they are able to achieve superior effluent quality. The effluent can be discharged to the subsurface as in a septic tank leach field or, in some cases, discharged directly to the surface

通过大自然的方法处理生物垃圾已经实施了几个世纪。然而事实上，在1925年，80%人口超过100,000的美国城市根本没有处理系统，工程化的污水好氧生物处理在美国的大规模实施仅仅才几十年。简单来说，好氧处理过程包括为生物体提供合适的富氧环境，该环境可以在有氧的情况下将废弃物的有机成分分解为二氧化碳和水。随着郊区和农村土地规模的日益发展，大型集中式污水处理系统并不总是容易建设，或者具有足够的成本效益。许多产权拥有者仍然依靠单独的化粪池或其他系统来原位处理和处置家庭废水。从历史经验看，好氧处理在以化粪池为主要的处理设施的小规模处理系统上是不可行的，但最近的技术进步使单体的好氧处理系统变得高效且经济实惠。耗氧系统与化粪池系统相似，因为它们都使用自然的过程来处理污水。但与化粪池（厌氧）处理不同，好氧处理过程中需要氧气。因此，好氧处理系统使用了一种在反应器内注入和循环空气的机制。因为好氧系统的处理过程更高速，它们的出水质量更优质。排出的废水可以像化粪池上清液一样排放到地表下，或者在某些情况下直接排放到地表。

Current Technologies

Individual aerobic systems have been in place since the 1950's, however, these early systems consisted of little more than an aerator placed in a traditional septic tank. They were prone to noise, odor and maintenance complaints, and were used only where standard septic tanks were not feasible. The newer aerobic treatment units are pre-engineered and operate at a high level of efficiency. The demand for these units and the desire for direct surface discharge of the treated waste stream has led to a certification process by the National Sanitation Foundation (NSF). This certification (NSF Standard 40 for Individual Wastewater Treatment Plants) applies to plants with capacities of up to 1,500 gallons per day, and leads to approval as a Class I or Class II plant. A Class I certification indicates performance to EPA Secondary Treatment Guidelines for three parameters: BOD, suspended solids and pH. Noise levels, odors, oily films and foaming are also measured.. The Class II criteria require that not more than 10% of the effluent CBOD5 values exceed 60 mg/L and that TSS not exceed 100 mg/L. As of June 2000, 15 manufacturers carry NSF 40 Class I Certification with available capacities ranging from 1514.2 Liters/day to 5,678.1 Liters/day (400 to 1,500 gallons per day). Table 1 provides a list of the certified manufacturers, the number of models available, and the range of flows treated. It is important to note that the NSF certified Product Listing is continually changing. The NSF should be contacted directly to confirm the status of the listing provided in Table 1. Table 2 shows the NSF Class I effluent performance limits.

当前技术

单体的好氧系统自1950年代以来已然存在。但是，这些早期的耗氧系统仅仅是加装在传统化粪池中的曝气器而已。它们容易产生噪音、气味和运行中的投诉，并且仅在传统的化粪池运行出现问题时才会被使用。稍新改良的的耗氧处理系统是预先设计的，并可以以更高效率运行。人们对这些好氧系统的需求以及希望处理后的污水能够直接地表排放的需求直接推动了美国国家卫生基金会 (NSF) 的认证过程。该认证（针对单个污水处理厂的NSF-40标准）适用于每天处理能力达到1,500加仑的工厂，评估后授予I类或II类污水厂的称号。获得I类认证说明三个出水水质指标能够满足EPA二级处理指南的要求，即BOD、悬浮固体和pH值满足排放限值，同时噪音水平、气味、油膜和泡沫也应被检测。II类标准要求只有不超过10%的出水的CBOD5值超过60 mg/L并且TSS不超过100 mg/L。

截至2000年6月，共有15家供应商获得了NSF-40的I类认证，处理能力从1514.2升/天到5,678.1升/天（每天400到1,500加仑）不等。表1提供了经过认证的供应商名录、产品型号的数量以及处理能力范围。值得注意的是通过NSF认证的名录是动态的，可以直接联系NSF以确认表1中列出的产品目前的认证状态。表2罗列了NSF I类认证要求的污水厂出水的水质限值要求。

Although there have been small scale “home aerobic systems” in the United States for more than 50 years, their use has been fairly limited, in part, because of the widespread use of septic systems, which are relatively inexpensive and easy to maintain. They are the most common onsite wastewater treatment systems in rural areas. However, many households may not be well suited for septic systems.

尽管美国小规模的“家用好氧系统”已经存在了50余年，但它们的应用仍相当有限，部分原因是相对便宜且易于维护的传统化粪池系统的广泛使用，因此化粪池仍然是农村地区最常见的污水原位处理系统。然而，许多家庭可能并不太适用化粪池系统。

For example, septic systems are not suitable for all decentralized wastewater treatment applications. In fact, approximately two-thirds of all land area in the United States is estimated to be unsuitable for the installation of septic systems (Linsley 1972). Some homes may not have enough land area or appropriate soil conditions to accommodate the soil absorption drainfield. In some communities, the water table is too high to allow the drainfield to give adequate treatment to the wastewater before it is returned to the groundwater.

例如，化粪池系统不适用于所有分散式的污水处理场景。事实上，由于一些家庭可能没有足够的土地面积或适当的土壤条件来消纳化粪池的排水，据估计，美国大约三分之二的土地并不适合安装化粪池系统。在一些社区，由于地下水位太高，化粪池的排放水在进入地下水之前，由于无法在土壤中拥有足够的自净空间而无法得到充分的处理。

Other site-related concerns include homes located on wooded lots or on lots close to a body of water. Homeowners in wooded areas may not want to clear enough land to install a septic tank and drainfield, and wastewater treated by a septic system is often not of high enough quality to be discharged near a body of water. One of the most common reasons to select aerobic wastewater treatment units is to replace failing septic systems, which are a major source of groundwater pollution in some areas. If a failed septic system needs to be replaced or if a site is inappropriate for a septic system, aerobic wastewater treatment may be a viable option.

其他与处理系统所在场地相关的问题也包括，如果房屋位于树木繁茂的区域或靠近水体的区域。房主可能难以清理出足够的土地来安装化粪池和并给排放水的自净预留足够的空间，这样就算经过化粪池系统处理的污水通常水质也不够好，无法在水体附近直接排放，这是某些地区地下水污染的主要来源。选择好氧污水处理系统的最常见原因之一就是要替换已经无法起到预设效果的化粪池系统。如果需要更换发生故障的化粪池系统或已不再适合安装化粪池系统，则好氧处理系统可能是一个可行的选择。

Advantages:

? Can provide a higher level of treatment than a septic tank

? Helps protect valuable water resources where septic systems are failing

? Provides an alternative for sites not suited for septic systems

? May extend the life of a drainfield

? May allow for a reduction in drainfield size

? Reduces ammonia discharged to receiving waters

优点：

? 可以提供比化粪池更高水平的处理

? 帮助保护宝贵的水资源免受化粪池排放水的污染

? 为不适合安装化粪池系统的区域提供替代方案

? 可以延长排水场（消纳化粪池排放水的土地区域）的使用寿命

? 可以减少排水场的面积大小

? 减少排放到受纳水体的氨的量

Disadvantages:

? More expensive to operate than a septic system

? Requires electricity

? Includes mechanical parts that can break down

? Requires more frequent routine maintenance than a septic tank

? Subject to upsets under sudden heavy loads or when neglected

? May release more nitrates to groundwater than a septic system

缺点：

? 比化粪池系统更昂贵的运行成本

? 需要电力

? 部分机械部件可能会发生故障

? 同化粪池相比，需要更频繁的日常维护

? 在突然加大的污染负载情况下，或运行状况异常没有被及时发现时，可能会失效

? 同化粪池系统相比，可能会排放更多的硝酸盐，对地下水产生影响

On-site aerobic processes typically produce a higher degree of treatment than septic tanks, but periodic carryover of solids due to sludge bulking, chemical disinfection addition, or excessive sludge buildup can result in substantial variability of effluent quality. Regular, semi-skilled operation and maintenance are required to ensure proper functioning of moderately complex equipment. Inspections every two months are recommended. Power is required to operate aeration equipment and pumps. Absorption beds are dependent upon site and soil conditions, and are generally limited to sites with percolation rates less than 2.4 minutes/millimeter (60 minutes/inch), depth to water table or bedrock of 0.61 to 1.2 meters (2 to 4 feet), and level or slightly sloping topography. Two aerobic primary systems have been adapted for onsite use: suspended growth and fixed film. In suspended growth systems, the microorganisms responsible for the breakdown of wastes are maintained in a suspension with the waste stream. In fixed film systems, the microorganisms attach to an inert medium. Very few commercially produced fixed film systems are available for onsite application, and they include a variety of proprietary devices, making it difficult to prescribe design guidelines. In many cases, however, design guidelines for fixed film systems are similar to those applied to suspended growth systems.

好氧处理系统通常比化粪池系统对污水的处理程度更高，但由于污泥膨胀、投加化学消毒剂或过多的剩余污泥堆积，一些固体漂浮物可能会随出水一起排放，导致出水质量的显着变化。操作曝气设备和泵需要电力，为了确保这种具有一定复杂性的设备的正常运转，需要定期的、比较熟练的操作和维护，一般建议每两个月检查一次。出水的排水场的设置取决于场地和土壤条件，通常仅限于渗透率小于 2.4 分钟/毫米（60 分钟/英寸）、地下水位或基岩深度为 0.61 至 1.2 米（2 至 4 英尺）的场地，地形应为平坦或略微倾斜的。目前适用于原位处理并普遍采用的有两种好氧处理系统：流化床和固定床。在流化床系统中，负责降解污染物的微生物相对污水保持悬浮状态。在固定床系统中，微生物附着在惰性介质上。在原位处理的应用场景中，很少有商业化的固定床系统通入应用，并且因为它们需要有各种专用设备，因此很难制定设计指南。但是，在大多数情况下，固定床系统的设计指南与悬浮床系统的设计指南是相似的。

Configuration

Most aerobic treatment units designed for individual home application range in capacity from 1514 to 5678 Liters (400 to 1,500 gallons), which includes the aeration compartment, settling chamber, and in some units, a pretreatment compartment. Based upon average household flows, this volume will provide total hydraulic retention times of several days.

配置

大多数为个人家庭的应用而设计的好氧处理装置的体积容量为1514到 5678升（400到1500加仑），内部分为曝气池和沉淀池，在某些设备中还包括了预处理池。根据平均家庭的污水排放量估算，这个体积范围足够保证几天的总水力停留时间。

Pretreatment

Some aerobic units provide a pretreatment step to remove grease, trash and garbage grindings. Pretreatment devices include trash traps, septic tanks, comminutors, and aerated surge chambers. The use of a trash trap or septic tank before the extended aeration process reduces problems with floating debris in the final clarifier, clogging of flow lines, and plugging of pumps. Pretreatment is required in fixed film systems to prevent process malfunction.

预处理

一些好氧处理系统中的预处理工序主要用来去除油脂、垃圾和粉碎后的垃圾。预处理设备包括垃圾收集器、化粪池、粉碎机和曝气储罐。在长时间的曝气过程之前使用垃圾收集器或化粪池可减少最终沉淀池中漂浮的碎屑，并减少管路堵塞和泵的堵塞等问题，特别是固定床系统，需要进行预处理以防止可能出现的故障问题。

Flow Mode

Suspended growth aerobic treatment plants may be designed as continuous or batch flow systems. The simplest continuous flow units provide no flow equalization and depend upon aeration tank volume and/or baffles to reduce the impact of hydraulic surges. Some units use more sophisticated flow dampening devices, including air lift or floatcontrolled mechanical pumps to transfer the wastewater from aeration tank to clarifier. Still other units provide multiple-chambered tanks to attenuate flow. The batch (fill and draw) flow system eliminates the problem of hydraulic variation. This unit collects and treats wastewater over a period of time (usually one day), then discharges the settled effluent through pumping at the end of the cycle. Fixed film treatment plants operate on continuous flow.

流体形式

悬浮生长的好氧处理系统可以设计为连续式或序批式的系统。最简单的连续系统不用保证流量的均衡，依靠曝气池的容积和/或挡板来减少流量波动时带来的冲击影响。一些系统会使用更复杂的流量阻尼装置，包括气浮或浮控机械泵将污水从曝气池转移到澄清池，还有一些系统会提供多个池体的设计以减弱流量波动的影响。序批式系统没有水力变化的问题，这种系统在一段时间（通常为一天）内收集和处理废水，然后在一个处理周期结束时通过泵排放沉淀的废水。固定床的系统一般都是以连续模式运行。

Method of Aeration

Oxygen is transferred to the waste stream by diffused air, sparged turbine, or surface entrainment devices. When diffused air systems are used, low pressure blowers or compressors force the air through diffusers on the bottom of the tank. The sparged turbine uses a diffused air source and external mixing, usually from a submerged flatbladed turbine. The sparged turbine is more complex than the simple diffused air system. A variety of surface entrainment devices are used in package plants to aerate and mix the wastewater. Air is entrained and circulated in the mixed liquor through violent agitation from mixing or pumping.

曝气方法

氧气通过扩散、涡轮喷射或表面曝气等装置转移到污水中，当使用扩散空气的方式时，低压鼓风机或压缩机迫使空气穿过反应器底部的曝气头；喷射式涡轮机将空气源和液体预先混合后，通常涡轮机进行注入，喷射式涡轮机比简单的扩散空气系统更复杂。在成套设备中大多使用了表面曝气装置来对污水进行曝气和混合。通过混合或机械泵的剧烈搅拌，氧气被混合在液相中往复。

Oxygen transfer efficiencies for these small package plants are normally low (3.4 to 16.9 kg O2 /MJ or 0.2 to 1.0 lb O2 /hp/hr) as compared with large-scale systems which may transfer 50.7 kg O2 /MJ or more (3+ lbs O2 /hp/hr). This difference is primarily due to the high power inputs to the smaller units. Normally, there is sufficient oxygen transferred to produce high oxygen levels. In an attempt to reduce power requirements or enhance nitrogen removal, some units use cycled aeration periods. Care must be taken to avoid developing poor settling biomass when cycled aeration is used. Mixing the aeration tank contents is also an important consideration in the design of oxygen transfer devices. Rule of thumb requirements for mixing in aeration tanks range from 0.465 to 0.931 kW/m3 (0.5 to 1 hp/1,000 ft3 ) depending upon reactor geometry and type of aeration or aeration system configuration. Commercially available package units are reported to deliver mixing inputs ranging from 0.005 to 2.8 kW/m3 (0.2 to 3 hp/1,000 ft3). Solids deposition problems may develop in units with lower mixing intensities.

与能够输送50.7kgO2/MJ或更多（3 + lbs O2 / hp / hr）的大型曝气系统相比，这些小型的成套系统的氧转移效率通常较低（3.4~16.9kgO2 / MJ或0.2~1.0 lb O2 / hp / hr）。这种差异主要是由于对较小单元的高功率输入。通常，足够的氧气传输会产生较高的氧含量水平。一些系统会使用循环曝气来降低功率需求或提高氮去除率。使用循环曝气时，必须注意避免产生沉降性不佳的污泥。曝气池内的混合程度也是氧气传输装置设计中的一个重要考虑因素。取决于反应器的几何形状和曝气类型或曝气系统配置，曝气池中充分混合的经验法则要求功率的范围从0.465到0.931千瓦/立方米（0.5到1马力/1000英尺3）。据报道，目前供应商在售的成套设备的功率范围为0.005~2.8 kW/m3（0.2~3 hp/1,000 ft3），在功率较低的系统中可能会出现污泥沉积的问题。

Biomass Separation

The clarifier is critical to the successful performance of the suspended growth process. A majority of commercially available package plants provide simple gravity separation. Weir and baffle designs have not been given much attention in package units. Weir lengths of at least 12 in. (30 cm) are preferred and sludge deflection baffles (Stamford baffles) should be included as a part of the outlet design. The use of gas deflection barriers is a simple way to keep floating solids away from the weir area.

生物质分离

沉淀的作用对生物悬浮生长过程的成功与否至关重要。大多数供应商生产的成套设备都提供简单的重力沉淀，但堰和挡板的设计在成套设备中没有得到很多关注。堰的长度至少应为12英寸（30厘米），并且污泥偏转挡板（Stamford挡板）应作为出口设计的一部分。使用气体偏转挡板是使悬浮固体远离堰区的一个简单方法。

Upflow clarifier devices have been used to improve separation, but hydraulic surges must be avoided in these systems. Filtration devices have also been employed in some units, but they are very susceptible to clogging.

上流式的沉淀池装置也被用于改善分离效果，但在这些系统中必须避免水力波动。过滤装置在一些系统中也被使用，但它们很容易堵塞。

Controls and Alarms

Most aerobic units are supplied with some type of alarm and control system to detect mechanical breakdown and to control the operation of electrica components. They do not normally include devices to detect effluent quality or biomass deterioration. These control systems are subject to corrosion because they contain electrical components. All electrical components should be waterproofed and regularly serviced to ensure their continued operation.

控制和警报

大多数的好氧系统都配备了某种类型的警报和控制系统，以检测机械故障并能控制电气设备的运行。它们通常不包括对出水水质的检测功能，或污泥状况的检测功能。这些控制系统因为包含电气元件容易被腐蚀，所有电气组件都应做好防水并定期维护，以确保其持续运行。

Additional Construction Features

Typical onsite extended aeration package plants are constructed of noncorrosive materials, including reinforced plastics and fiberglass, coated steel, and reinforced concrete. The unit may be buried as long as there is easy access to all mechanical parts, electrical control systems, and appurtenances requiring maintenance such as weirs, air lift pump lines, etc. Units may also be installed above ground, but should be properly housed to protect against severe climatic conditions. Installation should be in accordance with the manufacturers specifications.

其他结构特点

典型成套的原位曝气扩散设备由非腐蚀性材料构成，包括硬化塑料和玻璃纤维、涂层钢和钢筋混凝土。只要所有机械部件、电气控制系统和需要维护的附件（如堰、气举泵管线等）都方便使用，该装置就可以埋在地下。装置也可以安装在地面上，但应妥善安置以预防恶劣气候条件的影响。安装应符合供应商要求的规格。  

 Appurtenances for the plant should be constructed of corrosion-free materials including polyethylene plastics. Air diffuser support legs are normally constructed from galvanized steel or an equivalent. Large-diameter air lift units should be used to avoid clogging problems. Mechanical units should be waterproofed and/or protected from the elements.

成套设备中的附属设备应由包括聚乙烯塑料在内的无腐蚀材料制成。空气扩散器的支撑腿通常由镀锌钢或等效材料制成。应使用大直径的空气提升装置以避免堵塞问题。机械装置应防水和/或保护免受水中物质的影响。

For fixed film systems, synthetic packing or attachment media are preferred over naturally occurring materials because they are lighter, more durable, and provide better void volume-surface area characteristics.

对于固定床系统，合成填料或附着介质优于天然材料，因为它们更轻、更耐用，并提供了更好的空隙体积和比表面积。

Since blowers, pumps, and other prime movers are abused by exposure to severe environments, lack of attention, and continuous operation, they should be designed for heavy duty use. They should be easily accessible for routine maintenance and tied into an effective alarm system.

鼓风机、泵和其他原动机因暴露于恶劣环境、缺乏关注、无法连续运行而被滥用，因此它们应设计用于重载使用。它们应该易于接触到以进行日常维护，并与有效的警报系统相连。

In extended aeration package plants, long hydraulic and solids retention times (SRT) are maintained to ensure a high degree of treatment at minimum operational control, to hedge against hydraulic or organic overload to the system, and to reduce sludge production. Since waste of accumulated solids is not routinely practiced in many of these units, SRT increases to a point where the clarifier can no longer handle the solids, which will be uncontrollably wasted in the effluent. Treatment performance (including nitrification) normally improves with increasing hydraulic retention time and SRT to a point where excessive solids build-up will result in high suspended solids washout. This is one of the biggest operational problems with these extended aeration units, and is often the reason for poor performance.

成套的扩散曝气装置会保持较长的水力和污泥停留时间 (SRT)，以确保在最低限度的操作空间内进行高程度的处理，以应对系统的水力冲击或有机物负荷，并减少污泥产生。由于在这套系统中通常不会流失累积的剩余污泥，因此随着污泥停留时间的延长，沉淀池可能无法再有效进行沉淀，部分剩余污泥可能会不受控制地随出水排出中。处理效果（包括硝化作用）通常会随着水力停留时间和污泥停留时间的增加而提高，直到剩余污泥存量过大导致出水中SS过高，这是扩散曝气装置最大的操作问题之一，通常是运行情况不佳的原因。

Dissolved oxygen concentrations in the aeration tank should exceed 2 mg/L (1.669 x 10-8 pounds/gallon) to insure a high degree of treatment and a good settling sludge. Normally, onsite extended aeration plants supply an excess of dissolved oxygen due to minimum size restrictions on blower motors or mechanical drives. An important element of aeration systems is the mixing provided by the aeration process. Package units should be designed to provide sufficient mixing to ensure good suspension of solids and mass transfer of nutrients and oxygen to the microbes.

曝气池中的溶解氧浓度应超过2毫克/升（1.669 x 10-8 磅/加仑），以确保较高水平的处理和良好的污泥沉淀。通常，由于鼓风机电机或机械驱动器的最小尺寸限制，扩散曝气设备会提供过量的溶解氧。好氧系统设计的一个重要元素是伴随着曝气过程确保对固液相的充分混合。成套系统的设计应确保充分的混合能力，以确保生物固体的良好悬浮状态，以及营养物质和氧气向微生物的质量传递。 

Wastewater characteristics may also influence performance of the process. Excess amounts of certain cleaning agents, grease, floating matter, and other detritus can cause process upsets and equipment malfunctions.

污水的特性也可能影响工艺的运行效果。污水中含有过量的某些清洁剂、油脂、漂浮物和其他碎屑也会导致工艺混乱和设备故障。

Process efficiency may also be affected by temperature, generally improving with increasing temperature.

工艺运行的效率也可能受温度影响，通常随着温度的升高而提高。

The clarifier is an important part of the treatment process. If the biomass cannot be properly separated from the treated effluent, the process will fail. Clarifier performance depends upon the settleability of the biomass, the hydraulic overflow rate, and the solids loading rate. Hydraulic surges can result in serious clarifier malfunctions. As mentioned previously, high solids loadings caused by accumulation of mixed liquor solids result in eventual solids carryover. Excessively long retention times for settled sludges in the clarifier may result in gasification and flotation of these sludges. Scum and floatable material not properly removed from the clarifier surface will also impair effluent quality.

沉淀是好氧处理过程的重要组成部分。如果生物质不能从处理后的污水中适当分离，则整个处理过程将失败。沉淀过程的性能取决于生物质的沉降性、出水溢流率和固体负荷率。突然的水利冲击会导致严重的沉淀失效。如前所述，如果反应器内剩余污泥积累过多，混合液中悬浮物过多也会影响沉淀效果。剩余污泥在沉淀池中的停留时间过长可能导致污泥膨胀和上浮。未能从沉淀池表面正确清除的浮渣和可漂浮物质也会影响出水质量。

Generally, extended aeration plants produce a high degree of nitrification since hydraulic and solids retention times are high. Reductions of phosphorus are normally less than 25 percent. The removal of indicator bacteria (fecal coliforms) in onsite extended aeration processes is highly variable and not well documented. Reported values of fecal coliforms appear to be about two orders of magnitude lower in extended aeration effluents than in septic tank effluents.

通常，长时间的曝气会产生更强的硝化作用，因为水力停留时间和污泥停留时间很长，总磷的削减量通常低于25%。长时间的曝气过程中指示性的细菌（粪大肠菌群）的去除指标变化很大，除水中粪大的数量似乎比化粪池的出水低两个数量级。

Aerobic units can achieve higher BOD5 removals than septic tanks, but suspended solids removals, which are highly dependent on solids separation methods, are similar. Nitrification is normally achieved, but little reduction in phosphorus is accomplished. NSF studies indicate that suspended growth units can provide from 70 to 90 percent BOD5 and SS reductions for combined household wastewater, yielding effluent BOD5 and suspended solids concentrations as low as 20 mg/l.

与化粪池相比，好氧系统可以实现更高的 BOD5（5天的有机物耗氧量）去除率，但高度依赖于固液分离的方法，以及对除水中悬浮固体去除。好氧系统通常可以实现硝化，但对磷的削减量很少。NSF研究表明，流化床系统可将家庭污水的BOD5和SS降低70%~90%，从而出水BOD5和悬浮固体浓度可以低至20 mg/L。

General Plant Operation

The activated sludge process can be operated by controlling only a few parameters; the aeration tank dissolved oxygen, the return sludge rate, and the sludge wasting rate. For onsite package plants, these control techniques are normally fixed by mechanical limitations so that very little operational control is required. Dissolved oxygen is normally high and cannot be practically controlled except by “on or off” operation. Experimentation with the process may dictate a desirable cycling arrangement using a simple time clock control that results in power savings and may also achieve some nitrogen removal.

一般状况下的运营

活性污泥法只需控制几个参数即可运行：曝气池溶解氧、污泥回流比、排泥率。对于原位运行的成套系统来说，这些参数的控制通常受到系统的限制，因此极少需要操作控制。溶解氧通常很高，除非通过“开或关”操作，否则实际上无法控制。对该过程的操作可能会使用简单的时钟控制来确定理想的循环安排，这会节省电力且还可以去除一些氮。

The return sludge rate is normally fixed by pumping capacity and pipe arrangements. Return sludge pumping rates often range from 50 to 200 percent of the incoming flow. They should be high enough to reduce sludge retention times in the clarifier to a minimum (less than one hr), yet low enough to discourage pumping of excessive amounts of water with the sludge. Time clock controls may be used to regulate return pumping.

污泥回流比通常由泵送能力和管道布置决定。回流污泥的泵送率通常在流入流量的50%到200%之间。这个参数范围应该足以将沉淀池中的污泥停留时间降到最低限度（小于 1小时），但又要足够低以阻止泵送过量的水与污泥。时钟控制可用于调节泵送的能力。

Sludge wasting is manually accomplished in most package plants, usually during routine maintenance. Through experience, the technician knows when mixed liquor solids concentrations become excessive, resulting in excessive clarifier loading. Usually 8 to 12-month intervals between wasting is satisfactory, but this varies with plant design and wastewater characteristics. Wasting is normally accomplished by pumping mixed liquor directly from the aeration tank. Wasting of approximately 75 percent of the aeration tank volume is usually satisfactory. Wasted sludge must be handled properly.

大多数的成套设备在日常维护期间需要手动完成沉淀的剩余污泥的排出的。根据经验，技术人员知道混合液中固体浓度何时变得过高，从而导致沉淀池的负荷过大。通常8到12个月进行一次排泥的间隔是合适的，但这会因系统设计和污水特性而异。通常是通过直接从曝气池中抽出混合液来完成排泥过程的。排泥的体积大约为75%的曝气池体积是比较合适的，排出的的污泥必须妥善处理。

Start-up

Prior to actual start-up, a dry checkout should be performed to insure proper installation. Seeding of the plant with bacterial cultures is not required as they normally develop within a 6 to 12-week period. Initially, large amounts of white foam may develop, but will subside as mixed liquor solids increase. During start-up, it is advisable to return sludge at a high rate. Monitoring by qualified maintenance personnel is desirable during the first month of startup.

启动

在实际启动之前，应进行干燥（密封）检查以确保正确安装。不需要特别培养细菌等微生物，因为它们通常在6到12周的时间内会完成繁殖。最初，可能会产生大量白色泡沫，但会随着混合液固体的增加而消退。在启动期间，建议以较高的回流比回流污泥。在启动的第一个月内最好由合格的维护人员进行监控。

Routine Operation and Maintenance

The maintenance process for suspended growth systems is more labor-intensive than for septic systems and requires semi-skilled personnel. Based upon field experience with these units, 12 to 48 man-hours per year plus analytical services are required to ensure reasonable performance. Power requirements are variable, but range between 2.5 to 10 kWh/day (8,530.8 to 34,123.2 Btu/day). Maintenance for fixed film systems is less laborintensive but still requires semi-skilled personnel. Based upon limited field experience, 8 to 12 manhours per year plus analytical services are required for adequate performance. Power requirements depend upon the device employed, but range from 1 to 4 kWh/day (3,412.3 to 13,649.3 Btu/day). Maintenance for both types of aerobic treatment units is usually completed through routine contract services. No chemicals are required for either method unless chemical disinfection or additional nutrient removal (N and P) is required for surface discharge.

日常的运行和维护

流化床好氧系统的维护过程比化粪池系统更费力，并且需要半熟练的人员。为了确保合理的性能，运维需要对这些系统的现场经验，每年需要12到48个工时加上分析服务。曝气的功率要求是可变的，但范围在2.5到10 kWh/天（8,530.8 到34,123.2 Btu/天）之间。固定床好氧系统的维护劳动强度较低，但仍需要半熟练的人员。要获得足够的性能，同样需要根据一定的现场经验，每年需要8到12个工时加上分析服务。曝气功率要求取决于所使用的设备，但范围为1到4kWh/天（3,412.3 到 13,649.3 Btu/天）。两种类型的好氧处理系统的维护通常通过常规合同服务完成。任何一种方法都不需要添加化学药剂，除非向地表水直接排放需要化学消毒或额外的营养物质去除（N 和P）。

Operational Problems

Major mechanical maintenance problems for onsite treatment units include blower or mechanical aerator failure, pump and pipe clogging, electrical motor failure, corrosion and/or failure of controls, and electrical malfunctions. Careful attention to a maintenance schedule will reduce these problems and alleviate operational problems due to the biological process upset. Emphasis should be placed on adequate maintenance checks during the first 2 or 3 months of operation.

运行难点

现场原位安装的处理系统的主要机械维护问题包括鼓风机或机械曝气器故障、泵和管道堵塞、电动机故障、腐蚀和/或控制故障以及电气故障。仔细关注维护计划将减少这些问题并减轻由于生化系统紊乱引起的操作问题。在运行的前 2或3个月内，应着重进行充分的维护检查。

Costs for both suspended growth and fixed film systems of between 1,892 and 5,678 Liters/day (500 to 1,500 gallons per day) are typically in the $2,500 to $9,000 cost range, installed. These costs have been updated using the ENR construction cost index (ENR=6076). These units need more frequent maintenance than a traditional septic tank, and quarterly servicing is recommended. This maintenance cost averages $350 per year. Since many of these systems are being installed to replace failed septic systems, additional costs may be incurred to account for site conditions and additional piping.

1,892至5,678升/天（每天500至1,500加仑）的流化床和固定床好氧处理系统的安装成本通常在2,500至9,000美元之间。这些成本已使用ENR建设成本指数(ENR=6076)进行了核算更新。这些装置比传统的化粪池需要更频繁的维护，建议每季度进行一次维护。这种维护成本为每年平均350美元。目前正有大量的好氧系统在替换失效的化粪池系统，因此可能会产生额外的成本来考虑现场条件和额外的管道建设。