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美国EPA提供了一系列适用于污水处理系统的技术说明文件，供学习参考。
Wastewater Technology Fact Sheet
Disinfection for Small Systems
污水处理技术概况—小型系统的消毒
The impact of untreated and partially treated domestic wastewater on rivers and community water sources continues to raise health and safety concerns. The organisms of concern in domestic wastewater include enteric bacteria, viruses, and protozoan cysts. Table 1 summarizes the most common microorganisms found in domestic wastewater and the types of human diseases associated with them. Based on health and safety concerns associated with microorganisms present in wastewater, EPA has increased its efforts to address the wastewater treatment needs of all communities across the United States. As a result, small community wastewater treatment needs are an EPA priority.
因为对健康和安全的关心，未经处理和部分处理的生活污水对河流和下游社区的水源的影响持续得到人们的关注。生活污水中令人担忧的生物体包括肠道细菌、病毒和原生动物、孢囊。表1总结了生活污水中最常见的微生物以及与之相关的人类疾病类型。基于与污水中存在的微生物有关的健康和安全问题，美国环保总署加大了对全美所有社区的污水处理需求的解决力度。因此，小型社区的污水处理需求是环保局的一个优先事项。
According to the EPA, a small system can either be a septic system, sand filter, or any system that serves individual houses or groups of homes, strip malls, or trailer parks. These systems can handle flows from 3.8 to 76 m 3 /d (1,000 - 20,000 gpd). EPA estimates that more than 20 million homes in small communities are not connected to public sewers and that nearly one million homes in small communities across the United States have no form of sewage treatment at all (USEPA, 1999). In addressing small community needs, disinfection is considered a primary mechanism for inactivating/destroying pathogenic organisms and preventing the spread of waterborne diseases to downstream users and the environment. Some of the most commonly used disinfectants for decentralized applications include chlorine, iodine, and ultraviolet (UV) radiation.
根据环保局的说法，小型系统既可以是化粪池系统，也可以是沙滤器，或者是任何为单个房屋或住宅群、带状商场或拖车公园服务的系统。这些系统可以处理3.8至76立方米/天（1,000 - 20,000 gpd）的流量。美国环保局估计，小社区有2000多万个家庭没有连接到公共下水道，全美小社区有近100万个家庭根本没有任何形式的污水处理（美国环保局，1999）。在解决小社区的需求方面，消毒被认为是灭活/消灭病原体和防止水传播疾病向下游用户和环境传播的主要机制。一些最常用的分散式应用的消毒剂包括氯、碘和紫外线（UV）辐射。
Wastewater must be adequately treated prior to disinfection in order for any disinfectant to be effective. Reduction of suspended solids (SS) and biological oxygen demand (BOD) is recommended prior to disinfection. SS may absorb UV radiation, shield microorganisms, and increase chlorine demand. Removing SS also reduces the number of This fact sheet focuses on the use of UV disinfection and chlorination to disinfect small community septic systems.
污水在消毒前必须经过充分的处理，以使任何消毒剂都有效。建议在消毒前减少悬浮固体（SS）和生物需氧量（BOD）。悬浮物可能吸收紫外线辐射，屏蔽微生物，并增加氯的需求。去除SS也会减少存在的微生物数量。与BOD有关的有机化合物也会消耗添加的氯。
Chlorination and UV radiation can be used to inactivate potentially infectious organisms. As a result, communities and homeowners should carefully select a disinfection technology. A number of factors to consider when choosing a disinfection system are presented in Table 2.
氯消毒和紫外线辐射可用于灭活潜在的传染性生物体。因此，社区和业主应谨慎选择消毒技术。表2列出了选择消毒系统时需要考虑的一些因素。
The effectiveness of a UV disinfection system depends on the characteristics of the wastewater, the intensity of UV radiation, the amount of time the microorganisms are exposed to the radiation, and the reactor configuration. Disinfection success in any decentralized system is directly related to the concentration of colloidal and particulate constituents in the wastewater.
紫外线消毒系统的效果取决于污水的特性、紫外线辐射的强度、微生物暴露在辐射下的时间以及反应器的配置。任何分散式系统的消毒成功率都与污水中的胶体和颗粒成分的浓度直接相关。
The most common UV system used for small systems is a low-pressure, low-intensity system. Low-pressure signifies the pressure of the mercury in the lamp, which is typically 13.8 Pa (0.002 lbs/in2). The term intensity refers to the lamp power. Standard low-pressure, low-intensity lamps typically have a power of 65 watts. These lamps are generally efficient in producing germicidal wavelengths necessary for damaging DNA in bacteria. The low-pressure, low-intensity lamp typically has 40 percent of its output at 253.7 nm, which is within the ideal range for inactivating bacteria. This type of system can be configured vertically or horizontally. This allows systems to be configured to fit the available space. Safety considerations associated with UV disinfection include UV light itself, and potential release of mercury from lamp bulbs if damaged.
用于小型系统的最常见的紫外线系统是低压低强度的系统。低压指的是灯管中的汞压力，一般为13.8帕（0.002磅/英寸）。强度一词是指灯的功率。标准的低压低强度灯的功率通常为65瓦。这些灯通常能有效地产生破坏细菌中DNA所需的杀菌波长。低压低强度灯通常有40%的波长输出在253.7纳米，这在灭活细菌的理想范围内。这种类型的系统可以垂直或水平布置。这使得系统可以根据可用空间进行灵活调整。与紫外线消毒有关的安全考虑包括紫外线本身，以及如果灯管损坏可能释放出的汞带来的安全风险。
Chlorine is one of the most practical and widely used disinfectants for wastewater. Chlorination is commonly used because it can kill disease-causing bacteria and control nuisance organisms such as iron-reducing bacteria, slime, and sulfate-reducing bacteria. Chlorine destroys target organisms by oxidizing the cellular material of bacteria. Chlorine can be supplied in many forms and in liquid, solid, or gaseous phases. Common chlorine-containing disinfection products include chlorine gas, hypochlorite solutions, and chlorine compounds in solid or liquid form. Liquid sodium hypochlorite and solid calcium hypochlorite tablets are the most common forms of chlorine used for small systems because they are less hazardous than chlorine gas.
氯是最实用和被最广泛使用的污水消毒剂之一。氯之所以被普遍使用，是因为它可以杀死致病菌，并控制诸如铁还原菌、粘液和硫酸盐还原菌等滋生性生物。氯通过氧化细菌的细胞物质来破坏目标生物体。氯可以以多种形式，如液态、固态或气态的形式供应。常见的含氯消毒产品包括氯气、次氯酸盐溶液，以及固体或液体形式的氯化合物。液体次氯酸钠和固体次氯酸钙片是小型系统中最常见的氯形式，因为它们比氯气的危险性要小。
ADVANTAGES AND DISADVANTAGES（UV Radiation）
紫外消毒的优势和劣势
· Effective inactivation of most viruses, bacteria, and spores. May be effective against some cysts.
· Physical process rather than a chemical disinfectant.
· No residual effect that could harm humans or aquatic life.
· Equipment requires less space than other methods.
· 可以对大多数病毒、细菌和孢子有效灭活，可能对某些卵囊也有效。
· Low dosages may not effectively inactivate some viruses, spores, and cysts.
· Turbidity and total suspended solids (TSS) in the wastewater can render UV disinfection ineffective.
· May require a large number of lamps.
· 低剂量情况下可能无法有效灭活一些病毒、孢子和囊肿。
· 污水中的浊度和总悬浮固体（TSS）过高会导致紫外线消毒失效。
ADVANTAGES AND DISADVANTAGES（Chlorination）
氯消毒的优势和劣势
· Chlorine is reliable and effective against a wide spectrum of pathogenic organisms.
· Chlorine is more cost-effective than UV or ozone disinfection.
· The chlorine residual that remains in the wastewater effluent can prolong disinfection even after initial treatment and can be measured to evaluate the effectiveness.
· Dosing rates are flexible and can be controlled easily.
· 余留在污水中的氯气可以延长消毒时间，在初步处理后也可以通过检测以评估效果。
· The chlorine residual is toxic to aquatic life and the system may require dechlorination, even when low concentrations of chlorine are used.
· All forms of chlorine are highly corrosive and toxic. Thus, storage, shipping, and handling chlorine poses a risk and requires increased safety - especially in light of the new Uniform Fire Code.
· Chlorine reacts with certain types of organic matter in wastewater, creating hazardous compounds (e.g., trihalomethanes).
· Chlorine residuals are unstable in the presence of high concentrations of chlorine- demanding materials (BOD). Thus, wastewater with high BOD may require higher chlorine doses for adequate disinfection.
· 残留的氯对水生生物有毒性，即使只是投加低浓度的氯，排放前也可能需要脱氯。
· 所有形式的氯都具有高度的腐蚀性和毒性。因此，储存、运输和处理氯会带来风险，需要加强安全——特别是考虑到新的《统一消防法》的出台。
· 氯与污水中某些类型的有机物发生反应，会产生有害的化合物（如三卤甲烷）。
· 在高浓度的需氯物质（BOD）存在的情况下，残余氯是不稳定的。因此，高BOD的废水可能需要更高的氯剂量来进行充分消毒。
A UV disinfection system consists of mercury arc lamps, a contact vessel, and ballasts. The source of UV radiation is either a low- or a medium-pressure mercury arc lamp with low or high intensity. Medium- pressure lamps are generally used for large facilities. The optimum wavelength to effectively inactivate microorganisms is in the range of 250 to 270 nm. The intensity of the radiation emitted by the lamp dissipates as the distance from the lamp increases. Low-pressure lamps emit essentially monochromatic light at a wavelength of 253.7 nm. Standard lengths of the low-pressure lamps are 0.75 and 1.5 m (2.5 and 5.0 ft), with diameters of 15 to 20 mm (0.6-0.8 inches). The ideal lamp wall temperature is between 35 and 50EC (95-122EF). The United States Public Health Service requires that UV disinfection equipment have a minimum UV dosage of 16,000 FW@s/cm2.
紫外线消毒系统由汞弧灯、接触反应器和镇流器组成。紫外线辐射源是一个低强度或高强度的低压或中压汞弧灯。中压灯一般用于大型设施。有效灭活微生物的最佳波长是在250至270纳米之间。灯发出的辐射强度随着污水与灯的距离增加而消散。低压灯发出的单色光的波长基本上为253.7纳米。低压灯的标准长度为0.75和1.5米（2.5和5.0英尺），直径为15到20毫米（0.6-0.8英寸）。理想的灯壁温度在35到50EC（95-122EF）之间。美国公共卫生局要求紫外线消毒设备的最低紫外线剂量为16,000。
There are two types of UV disinfection reactor configurations: contact and noncontact. In both types, wastewater can flow either perpendicular or parallel to the lamps. In the contact reactor, a series of mercury lamps are enclosed in quartz sleeves to minimize the cooling effects of the wastewater. Flap gates or weirs are used to control the level of the wastewater. In the noncontact reactor, UV lamps are suspended outside a transparent conduit which carries the wastewater to be disinfected. In both types of reactors, a ballast—or control box—provides a starting voltage for the lamps and maintains a continuous current.
有两种类型的紫外线消毒反应器配置：接触和非接触。在这两种类型中，污水的流动方向可以与灯管垂直或平行。在接触型反应器中，一系列汞灯被封闭在石英套管中，以减少污水对灯管直接的冷却效果。可以用挡板或堰来控制污水水位的高度。在非接触式反应器中，紫外灯悬挂在透明管道的外面，该管道携带待消毒的污水。这种配置不像接触反应器那样常见。在这两种类型的反应器中，整流器或控制箱为灯管提供启动电压并维持连续的电流供给。
Because of capital cost advantages at low flow rates and the ease of managing a system with a small number of lamps, the majority of UV systems handling less than 0.4 m 3 /s (1 MGD) are low- pressure, low-intensity systems. A 0.4 m 3 /s (1 MGD) system should have fewer than 100 low- pressure lamps, so the impact of further reducing the number of lamps will not be substantial. Figure 1 presents a schematic of a low pressure contact UV disinfection system.
在低流速下，由于投资成本的优势和少量灯管的系统更易于管理，大多数处理量低于0.4m 3 /s (1 MGD)的紫外消毒系统是低压、低强度的系统。一个0.4 m 3 /s (1 MGD)的系统应该有少于100支低压灯管，所以进一步减少灯管数量的影响不会很大。图1是一个低压接触型紫外线消毒系统的示意图。
Several wastewater characteristics must be evaluated before selecting UV disinfection as a treatment method. The following list of characteristics can affect the performance and design of a UV disinfection system:
在选择紫外消毒作为处理方法之前，必须对污水的特性进行评估。下面列出的特性会影响到紫外消毒系统的性能和设计：
· Flow Rate: Wastewater flow can vary daily and seasonally, affecting the required size of a UV disinfection facility. As a result, the peak hourly flow rate typically is used as the design flow rate. The applied UV dosage is a function of UV intensity and the duration of exposure; the dosage rate achieved is directly proportional to flow rate.
· 流速：污水流量每天和季节性都会有变化，影响到所需紫外线消毒设施的规模。因此，每小时的峰值流速通常被用作设计流速。使用的紫外线剂量是紫外线强度和照射时间的函数；达到的剂量率与流速成正比。
· UV Transmittance: UV transmittance is a measure of the quantity of UV light at the characteristic wavelength of 253.7 nm transmitted through wastewater per unit depth. Historically, a 50 percent UV transmittance has been accepted as the minimum transmittance for which UV disinfection is practical. High turbidity and/or high concentrations of BOD, certain metals, TDS, TSS, and color may decrease transmittance, lessening the effectiveness of UV radiation.
· 紫外线透射率：紫外线透过率是衡量每单位深度上，253.7纳米特征波长的紫外线透过污水的剂量。根据历史数据分析，50%的紫外线透过率被认为是紫外线消毒实用的最小透过率。高浊度和/或高浓度的BOD、某些金属、TDS、TSS和颜色可能会降低透光率，减少紫外线辐射的效果。
· TSS Concentration: TSS levels significantly affect UV disinfection because UV light can be blocked by suspended solids. This can shield microorganisms from the disinfecting effects of the light. As a result, measuring the particle size distribution in wastewater can be helpful in determining the feasibility of this disinfection technology. Particles with a diameter of <10 microns allow for easy UV penetration. Particles with diameters between 10 and 40 microns can be completely penetrated, but with increased UV demand.
· TSS浓度：TSS水平明显影响紫外线消毒，因为紫外线会被悬浮物阻挡。这可以使微生物免受光线的消毒作用。因此，测量污水中的颗粒大小分布有助于确定这种消毒技术的可行性。直径小于10微米的颗粒可以使紫外线容易穿透。直径在10到40微米之间的颗粒可以被完全穿透，但对紫外线的需求会增加。
· Microorganism Concentration: UV disinfection performance evaluations indicate that the microorganism density remaining after exposure to a given UV dose is proportional to initial microorganism density. As a result, it is beneficial to consider the concentration of microorganisms before disinfection.
· 微生物的浓度：紫外线消毒性能评估表明，暴露在一定的紫外线剂量下，剩余的微生物密度与初始微生物密度成正比。因此，在消毒前评估微生物的浓度是有益的。
· Hardness: Carbonate deposition (scaling) on lamp sleeves becomes an issue when handling wastewater with high levels of hardness. Carbonate accumulation on lamp sleeves reduces the intensity of UV light reaching the wastewater.
· 硬度：当处理高硬度的污水时，灯套上的碳酸盐沉积（结垢）成为一个问题。碳酸盐在灯套上的积累会降低到达污水中的紫外线强度。
· Iron Concentration: Dissolved iron concentrations in wastewater can absorb UV light, reducing the light intensity reaching the microorganisms. Adsorbed iron on suspended solids may also shield microorganisms from UV light. Iron hydroxides may precipitate on lamp bulbs, decreasing their intensity.
· 铁的浓度：污水中溶解性的铁浓度可以吸收紫外线，降低到达微生物的光强度。悬浮物上吸附的铁也可能屏蔽微生物的紫外线。铁的氢氧化物也可能沉淀在灯管上，降低其强度。
· Organics: Dissolved organics or oils and grease can reduce UV transmittance. The size of the organic compounds is important in determining whether they will interfere with the UV transmittance: the larger the molecular weight of the compounds, the more they will interfere. This effect is primarily the result of increasing color and/or turbidity in the water.
· 有机物：溶解性的有机物或油和油脂可以降低紫外线的透射率。有机物尺寸的大小对判断它们是否会干扰紫外线透射率很重要：化合物的分子量越大，它们的干扰就越大。这种影响主要来自水的颜色和/或浊度增加的结果。
· Inorganics: Some inorganic salts (e.g., bromide) can absorb UV light and thereby reduce UV effectiveness.
· 无机物：一些无机盐（如溴化物）可以吸收紫外线，从而降低紫外线的有效性。
Systems using an aerobic household wastewater treatment system are usually installed at or below grade level and the effluent pipe may be as much as 60 cm (24 in) below grade. To maintain gravity flow, the UV unit must be below grade and must have very low flow resistance. During construction, the omponents of an underground UV system must be easily accessed for service and low voltage should be used for safety.
使用好氧家用污水处理系统的系统通常安装在地面或低于地面，污水管可能在地面以下60厘米（24英寸）。为了保持重力流动，紫外线装置必须在地表以下，并且必须有非常低的流动阻力。在施工过程中，地下紫外线系统的组件必须容易接近，以便进行维修，为了安全起见，应该使用低电压。
For optimum performance, a chlorine disinfection system should provide rapid initial mixing and a plug flow contact regime. The goal of proper mixing is to enhance disinfection by initiating a reaction between free chlorine and ammonia nitrogen. This helps to prevent free chlorine from reacting with organic carbon compounds and forming hazardous byproducts. In order to allow appropriate time for the disinfection reaction, the contact chamber should be designed with rounded corners to eliminate dead flow areas. It should also be baffled to minimize short-circuiting. This design allows for adequate contact time between the microorganisms and a minimal chlorine concentration for a specific period of time. Figure 2 illustrates plug flow chlorine contact basins.
为了获得最佳的性能，氯消毒系统应提供快速的初始混合和塞流式的接触。充分混合的目的是通过启动游离氯和氨氮之间的反应来提高消毒效果。这有助于防止游离氯与有机碳化合物反应，产生有害的消毒副产品。为了给消毒反应留出充足的时间，消毒接触池应设计成圆角，以消除死流区。接触池内还应该设有挡板，以尽量减少短路现象，这种设计可以使微生物和哪怕最小的氯浓度也可以在特定的时间内有足够的接触时间。图2是一种塞流式氯消毒接触池的形式。
Source: Crites and Tchobanoglous, 1998.
资料来源：Crites和Tchobanoglous，1998年。
FIGURE 2 TYPICAL PLUG FLOW CHLORINE CONTACT BASINS FOR SMALL FLOWS
图2 常见的用于小流量的塞流式氯消毒接触池
Chemical feed systems are used for adding sodium and/or calcium hypochlorite solutions. For sodium hypochlorite, the basic components of a chemical feed system include a plastic or fiber glass storage reservoir, metering pumps, and an injection device to inject the hypochlorite solution into a contact tank or pipeline. Calcium hypochlorite can typically be added to the wastewater either by mixing calcium hypochlorite powder in a mixing device and then injecting it into the wastewater stream, or by immersing chlorine tablets in the wastewater using a tablet chlorinator. Tablet chlorinator systems are described in more detail below.
化学加药系统用于投加次氯酸钠和/或次氯酸钙溶液。就次氯酸钠而言，化学加药系统的基本组成部分包括一个塑料或玻璃纤维储存库、计量泵和一个将次氯酸钠溶液注入接触罐或管道的注射装置。次氯酸钙通常可以通过在混合装置中预先混合溶解次氯酸钙粉末，然后注入污水中，或者通过使用片剂加氯机将氯片浸入污水中来添加到污水中。下面将对片剂加氯机系统进行详细介绍。
A typical calcium hypochlorite tablet chlorinator consists of a cylindrical PVC tank with a diameter ranging from 230 to 610 mm (9-24 in) and a height ranging from 0.6 to 1.2 m (24-48 in). A sieve plate with holes supports the 80 mm (3-in) diameter calcium hypochlorite tablets. Tablet chlorinator systems can typically provide between 1 and 295 kg (2-650 lbs) of chlorine per day. A side stream from the main flow is piped into the rises through the holes in the sieve plate, contacting and eroding the bottom layer of tablets. The tablets erode at a predictable rate based on the amount of water that enters the chlorinator. An accurate chlorine dosage can be achieved by controlling the water flow rate through the chlorinator. The chlorinator effluent is returned to the main stream, providing the desired level of available chlorine to meet operational requirement.
一般的次氯酸钙片剂加氯机由一个圆柱形的PVC罐组成，直径从230到610毫米（9-24英寸）不等，高度从0.6到1.2米（24-48英寸）不等，由一个带孔的筛板支撑着直径80毫米（3英寸）的次氯酸钙片。片剂加氯机系统通常可以每天提供1到295公斤（2-650磅）的氯。主干管引出旁路，污水通过管道进入水箱底部的氯化器，流水通过筛板上的孔上升，接触并侵蚀底层的药片。根据进入加氯器的水量，药片的溶解速度是可以预测的。通过控制通过加氯器的水流量，可以实现准确的加氯量。加氯器的出水被送回主干管，即可提供所需水平的可用氯，以满足运行要求。
The required degree of disinfection can be achieved by varying the dose and the contact time for any chlorine disinfection system. Chlorine dosage will vary based on chlorine demand, wastewater characteristics, and discharge requirements. The dose usually ranges from 5 to 20 mg/L. Table 3 describes some common wastewater characteristics and their impact on chlorine. Several other factors ensure optimum conditions for disinfection, including temperature, alkalinity, and nitrogen content. Wastewater pH affects the distribution of chlorine between hypochlorous acid and hypochlorite. A lower pH favors hypochlorous acid, which is a better disinfectant. High concentrations of hypochlorous acid, however, may result in production of chlorine gas, which may be hazardous.
任何氯消毒系统都可以通过改变剂量和接触时间来达到所需的消毒效果。加氯的剂量会根据对氯的需求、污水的特性和污水排放要求而变化。剂量通常在5到20毫克/升之间。表3描述了一些常见的污水特性及其对氯消毒效果的影响，包括温度、碱度和氮含量等其他几个因素都可能影响消毒的最佳条件。污水的pH值会影响氯气在次氯酸和次氯酸盐之间的分布，较低的pH值有利于次氯酸的生成，它是一种更好的消毒剂，但是，高浓度的次氯酸可能会导致产生氯气，这可能是危险的。
TABLE 3 WASTEWATER PROPERTIES AFFECTING CHLORINATION AND UV DISINFECTION PERFORMANC
表3 影响氯化和紫外线消毒性能的污水特性
Performance of chlorination and UV disinfection varies between facilities based on maintenance techniques and wastewater characteristics. Researchers at Baylor University are evaluating existing on-site systems using different disinfection units.
根据维护技术和污水特性，不同设施的加氯和紫外线消毒的性能各不相同。贝勒大学的研究人员正在评估使用不同消毒装置的现有现场系统。
OPERATION AND MAINTENANCE
运行和维护
A routine operation and maintenance (O&M) schedule should be developed and implemented for any disinfection system. A proper O&M program for a UV disinfection system should ensure that sufficient UV radiation is transmitted to the organisms to inactivate them. All surfaces between the UV radiation and the target organisms must be cleaned, while ballasts, lamps, and the reactor must be functioning properly. Inadequate cleaning is one of the most common causes of ineffective UV systems. The quartz sleeves or Teflon tubes should be cleaned regularly, either manually or through mechanical methods. Common cleaning methods include mechanical wipers, ultrasonic baths, or chemicals. Cleaning frequency is site-specific.
任何消毒系统都应该制定和实施常规的运行和维护（O&M）计划。紫外线消毒系统的正确运行和维护计划应确保有足够的紫外线辐射传递给生物体并使其失活。紫外线辐射和目标生物体之间的所有表面必须被清洁，同时镇流器、灯管和反应器必须正常工作。清洁不充分是导致紫外线系统失效的最常见原因之一。石英套筒或聚四氟乙烯管应定期清洗，可以是手动或机械方法。常见的清洁方法包括机械擦拭、超声波清洗或化学品清洗，清洁频率因地制宜。
Chemical cleaning is most commonly performed with citric acid or commercially available cleaning solutions. Other cleaning agents include mild vinegar solutions and sodium hydrosulfite. A combination of cleaning agents should be tested to find those that are most suitable for the specific wastewater characteristics without producing harmful or toxic by-products. Non-contact reactor systems are most effectively cleaned with sodium hydrosulfite.
化学清洗最常见的是用柠檬酸或市面上的清洗液进行。其他清洗剂包括温和的醋溶液和亚硫酸氢钠。应测试各种清洁剂的组合，以找到最适合特定污水特性而又不产生有害或有毒副产品的清洁剂。非接触反应器系统用亚硫酸钠清洗最为有效。
Average lamp life ranges from 8,760 to 14,000 working hours (between approximately 12 and 18 months of continuous use), but lamps are usually replaced after 12,000 hours of use. Operating procedures should be set to reduce the on/off cycles of the lamps, because repeated cycles reduce their effectiveness. In addition, spare UV lamps should be kept on hand at all times along with accurate records of lamp use and replacement. The UV output gradually decreases over the life of the lamp and the lamp must be replaced based on the hours of use or a UV monitor. The quartz sleeves that fit over the lamps will last about 5 to 8 years but are generally replaced every 5 years.
灯管的平均寿命在8760到14000个工作小时之间（大约连续使用12到18个月），但通常在使用12000个小时后就要更换灯管。操作程序应设置为减少灯管的开/关周期，因为反复的开关会降低其有效性。此外，备用的紫外线灯管应始终常备，同时准确记录灯管的使用和更换情况。紫外线输出在灯管的使用寿命内会逐渐减少，必须根据使用时间或通过紫外线监测器的判断来更换灯管。安装在灯管上的石英套筒可以持续5到8年，但一般每5年更换一次。
The ballast must be compatible with the lamps and should be ventilated to prevent excessive heating, which may shorten its life or even result in fires. The life cycle of ballasts is approximately 10 to 15 years, but they are usually replaced every 10 years.
镇流器必须与灯管兼容，并应通风以防止过度加热，因为这可能会缩短其寿命甚至导致火灾。镇流器的生命周期大约为10到15年，但通常每10年更换一次。
Operation and maintenance of an on-site system is usually the responsibility of the homeowner, but some home sewage systems are sold with service contracts that call for a trained serviceman to inspect the system and perform necessary maintenance every six months. As a result, it is necessary to determine who is responsible for operation and maintenance of the UV system.
现场系统的运行和维护通常是用户自己的责任，但一些家庭污水处理系统在出售时附有服务合同，要求训练有素的服务人员每6个月检查一次系统并进行必要的维护。因此，有必要事先明确由谁来负责紫外线系统的操作和维护。
O&M for a chlorine disinfection system should include the following activities:
? Follow all manufacturer recommendations and test and calibrate equipment as recommended by the manufacturer.
? Disassemble and clean system components, including meters and floats, every six months.
? Inspect and clean valves and springs annually.
? If the system includes metering pumps, maintain pumps on a regular basis.
? Remove iron and manganese deposits with muriatic acid or other removal agents.
? If gaseous chlorine is stored on-site, develop an emergency response plan in case of accidents or spills.
- 遵循所有供应商的建议，按照供应商的建议测试和校准设备。
- 每六个月拆卸和清洁一次系统部件，包括仪表和浮球。
- 如果现场储存气态氯，要制定应急计划，以防发生事故或溢出。
It is essential to properly and safely store all chemical disinfectants when using chlorine. The storage of chlorine is strongly dependent on the compound phase. Heat, light, storage time, and impurities such as iron accelerate the degradation of sodium hypochlorite. Calcium hypochlorite is unstable under normal atmospheric conditions and should be stored in a dry location. Hypochlorites are destructive to wood, corrosive to most common metals, and will irritate skin and eyes if there is contact. For further details on the safe use and storage of chlorine refer to the Material Safety Data Sheets (MSDS) for the specific chemicals of interest. MSDSs are readily available from the internet by doing a search on the chemical name.
使用氯气时，必须正确和安全地储存所有化学消毒剂。氯气的储存在很大程度上取决于化合物的相位。热、光、储存时间和铁等杂质会加速次氯酸钠的降解。次氯酸钙在正常大气条件下是不稳定的，应储存在干燥的地方。次氯酸钠对木材有破坏性，对大多数普通金属有腐蚀性，如果直接接触会刺激皮肤和眼睛。关于安全使用和储存氯气的进一步细节，请参考有关特定化学品的材料安全数据表（MSDS）。在互联网上搜索化学品名称，就可以得到MSDS。
The costs associated with chlorination and UV treatment are predominantly dictated by dosage, which in turn is related to peak flows, suspended solids, temperature and bacterial counts. The following summaries describe some of the costs that a homeowner and/or community may encounter when considering chlorination or UV treatment to disinfect wastewater.
氯消毒和紫外线消毒的相关费用主要由剂量决定，而剂量又与峰值流量、悬浮物、温度和细菌数有关。下面大致描述了用户和/或社区在考虑用氯消毒或紫外线消毒时可能发生的一些成本。
Table 4 provides capital cost summaries for UV systems. Systems include the wastewater channel, UV module assemblies with lamps and quartz sleeves, and ballasts. The ballasts include meters for run times and UV intensity. The last two systems in the table also include costs for delivery of the equipment to the site.
表4提供了紫外线系统的资本成本汇总。系统包括污水通道、带灯管和石英套管的紫外线模块组件以及镇流器。镇流器包括运行时间和紫外线强度的仪表。表中的最后两个系统还包括将设备运送到现场的费用。
TABLE 4 UV SYSTEM COSTS
表4 紫外消毒系统的成本
Sources:
1 Tipton Environmental International, Inc., 2003.
2 Infilco Degremont, Inc., 1999.
资料来源：
1蒂普顿环境国际公司，2003年。
2 Infilco Degremont, Inc., 1999年。
Most decentralized systems use chlorine tablets to disinfect their wastewater because they are simple to use, and they are less expensive than liquid chlorine. These units can range from $325-$700, depending on the flow to be chlorinated. Tablets are sold in tablets or drums based on weight. For example, a 100 kg (45 lb) pail of tablets ranges in cost from $69-$280, depending on the vendor.
大多数的分散式系统会使用氯片对污水进行消毒，因为它们使用起来很简单，而且比液氯便宜。这些装置的价格从325-700美元不等，取决于需要加氯的流量。片剂是根据重量以片或桶为单位出售的。例如，一桶100公斤（45磅）的片剂价格从69美元到280美元不等，取决于供应商。
Liquid chlorinators are more complex because the liquid must be pumped into the system. A hypochlorinator system sized to treat a flow range of 9.5 to 76 m 3 /d (2,500 to 20,000 gpd), consisting of one 210-L (55-gal) polyethylene drum, two metering pumps, and injector valve, costs approximately $4,200.
液态加氯器更为复杂，因为液体必须被泵入系统。一个处理流量范围为9.5至76立方米/天（2,500至20,000加仑/天）的次氯酸盐加氯系统，由一个210升（55加仑）聚乙烯桶、两个计量泵和喷射阀组成，成本约为4,200美元。
Cost comparisons between UV and chlorination disinfection systems are difficult because of the cost differences based on the volume of flow. In addition, while the initial capital costs of one system may be low relative to another system, subsequent operation and maintenance costs for each type of system must be evaluated before the overall cost-effectiveness of one system vs. another can be determined. For example, while the capital costs of a chlorination system may be low compared to the capital costs for a UV system, dechlorination equipment and supplies will increase the overall cost associated with this disinfection method.
紫外线消毒系统和加氯消毒系统之间的成本比较是很困难的，因为基于流量的成本差异。此外，虽然可能某个系统的投资资本成本比另一个系统低，但在确定一个系统与另一个系统的总体成本效益之前，必须评估每种系统的后续运行和维护成本。例如，虽然加氯系统的投资成本与紫外线系统的投资成本相比可能很低，但除氯设备和用品会增加这种消毒方法的总成本。
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