【正文】 d to transport toilet waste. To prevent clogging from grease, the pipes should be installed straight (no necks or depressions) with a gradient of at least %.In smaller systems, greywater can often be led directly to a mulch bed where the water is used for growing plants or trees. The design and dimensions of the systems needs to allow for the water to be assimilated by the soilecosystem. For larger systems where the water may be stored for long periods, a need for pretreatment arises. Suspended solids (SS) need to be removed because they may clog the system or create bad odours. The SSparticles can be removed mechanically by gravity, as in a septic tank system, by screens or filters on prefabricated equipment or as cheaper gravel filters for the smaller scale.Greywater is relatively harmless from an environmental and hygienic point of view. Problems are often small and local. But if not managed properly, greywater will be a strong source of smell due to the high levels of easily degradable pounds. When these pounds are broken down, natural processes can create anaerobic conditions within hours, causing bad odours. Other treatment targets are to reduce the levels of organic pollutants, heavy metals, pathogens, and other microorganisms.The most mon treatment technique is to use biofilm systems thatfilter greywater through substrates colonized by attached bacteria sothat biological degradation of organic matters takes place under aerated conditions. With a good oxygen supply ,foul odours can be avoided. These systems range from extensive land systems to intensive and energydemanding applications such as trickling filters and bio rotors.These slow rate systems use the soil ecosystem to convert polluted water into valuable plant production. They should be dimensioned from the requirements of the green plants. Too much water leads to saturation and the crops will suffer. Too little water on the other hand stresses the plants and makes them sensitive. The amount of water applied depends on the evapotranspiration rate, usually 215 litres per m2 per day. An alternative to watering the whole area is to use mulch beds for direct application close to the crops or the trees.The somewhat confusing concept “constructed wetland” often appears in the literature. A soil filter should not be designed and operated as wetland. For efficient filtering and aeration, it is important that the soil is not saturated with water. The water should percolate through the soil in the small pores, leaving the bigger pores open andaerated to allow for better gas exchange. A vertical soil filter system that is properly designed and operated has a removal efficiency for suspended solids and organic pounds of 9099%. Pathogens, including bacteria and viruses, can be expected to decrease by %.Phosphorus (P) and heavy metal removal is significant. P removal is estimated between 30 and 95%, depending on soil properties, depth of the unsaturated zone and wastewater load. Nitrogen is reduced by nitrification and denitrification, usually in the range of about 30%.Based on Ridderstolpe, P. 2004. Introduction to Greywater Management. EcoSanRes Publication Series. Report 20044. Stockholm Environment Institute。 Stockholm, Sweden.在所有的家庭廢水中除廁所污水外的所有廢水都被稱為洗滌水。這包括洗澡水、淋浴水、洗碗水和洗衣水。家庭產(chǎn)生的洗滌水量是非常巨大的。在缺水地區(qū)每人每天的用水量低至1520升，而在富水地區(qū)每人每天的用水量多達(dá)前者的十倍。在生態(tài)環(huán)境衛(wèi)生中，洗滌水來源是與廁所排水系統(tǒng)分離的，以便于讓洗滌水擁有比傳統(tǒng)污水處理設(shè)備更為簡單的處理系統(tǒng)。洗滌水的成功管理同時包括技術(shù)手段以及使用者正確參與系統(tǒng)的運(yùn)行和維護(hù)。整個系統(tǒng)從起始點(diǎn)一直到最終排放的所有部分，在規(guī)劃時都應(yīng)被考慮到。洗滌水含有的成分非常廣泛，這反映了居民的生活方式以及用來洗衣服或洗澡等的化學(xué)產(chǎn)品的選擇。典型的洗滌水包含很高濃度的可降解有機(jī)物，比如烹飪產(chǎn)生油類和脂類以及肥皂或其他洗滌劑產(chǎn)生的剩余物?；旧现挥挟?dāng)洗滌水輕微被糞便污染后才會含有病原體。盡管如此，洗滌水的環(huán)境仍然是很有利于細(xì)菌的生長，這也意味著洗滌水在回收利用之前應(yīng)當(dāng)進(jìn)行處理。除此之外，未經(jīng)處理的洗滌水會很輕易地變成厭氧（其中的氧被耗盡）而產(chǎn)生臭氣。洗滌水中的營養(yǎng)成分與平常的混合污水相比通常是較低的。在一些情況下洗滌水中可能會含有高濃度的磷，但是氮的濃度一直都是很低的。如果人們使用無磷洗滌劑的話，那么洗滌水中的磷含量會減少至比經(jīng)過預(yù)處理過的污水中的更低，因此來將回收利用前過程中的這一步降到最低。雖然通常情況下洗滌水中金屬和有機(jī)污染物的成分很低，但是它們的含量仍然可以通過危害環(huán)境的物質(zhì)進(jìn)入洗滌水中而增加。金屬物質(zhì)通常來自水本身，如來自于管道系統(tǒng)的銹蝕或者家用的洗發(fā)水、餐具等等。有機(jī)污染物則在許多我們家用的化學(xué)藥品中存在，比如洗發(fā)水、膠水、防腐劑以及清潔劑等。在這種情況下，人們可能嚴(yán)重影響洗滌水的成分。通過使用環(huán)境友好的化學(xué)藥品以及不傾倒有害物質(zhì)比如油漆和有機(jī)溶劑進(jìn)入下水道，洗滌水中金屬和有機(jī)污染物的含量可以保持很低。計劃處理的必要性在任何洗滌水管理中都應(yīng)被視為一個重要部分。這可以通過控制污染負(fù)荷以及用水量來加以實(shí)現(xiàn)。所以，所有的洗滌水系統(tǒng)包含關(guān)于用戶家用環(huán)境友好的化學(xué)藥品以及保存水的技術(shù)手段的信息都是非常重要的。將使用節(jié)水器具和經(jīng)濟(jì)獎勵政策相結(jié)合，如消耗水的收費(fèi)系統(tǒng)，洗滌水產(chǎn)生的量將會顯著降低。當(dāng)規(guī)劃城市下水道系統(tǒng)時，目標(biāo)應(yīng)當(dāng)是每人每天不產(chǎn)生超過80升的洗滌水。一個管道系統(tǒng)對于洗滌水的收集和輸送是必不可少的，這與傳統(tǒng)的混合污水系統(tǒng)相比，這里因?yàn)椴恍枰斔蛶盼塾玫墓艿揽梢愿?xì)。為了防止管道被油脂堵塞，%的坡度筆直地安裝（沒有凸出或凹進(jìn)）。在小型系統(tǒng)中，洗滌水經(jīng)常被直接導(dǎo)入一張覆蓋物床以用來澆灌植物或者樹木。系統(tǒng)的設(shè)計以及規(guī)模需要允許水被土壤生態(tài)系統(tǒng)吸收。在大型系統(tǒng)中，洗滌水可能要貯存較長時間，因此預(yù)處理的要求就被提出了。懸浮固體（SS）需要被除去，因?yàn)槠淇赡茏枞到y(tǒng)或者產(chǎn)生臭氣。懸浮固體顆?？梢酝ㄟ^重力的機(jī)械手段去除，比如化糞池系統(tǒng)，通過網(wǎng)屏或者預(yù)制構(gòu)件設(shè)備上的過濾器以及成本更低的小規(guī)模礫石過濾器。從一個環(huán)境和衛(wèi)生的角度來看，洗滌水是相對無害的。問題通常都是小的且局部的。但是如果管理不到位，那么由于高濃度的易降解成分，洗滌水會成為臭氣的極大來源。當(dāng)這些成分被降解后，其自然過程會在數(shù)小時內(nèi)產(chǎn)生厭氧環(huán)境，并產(chǎn)生臭氣。一些其他的處理目標(biāo)就包括降低有機(jī)污染物的水平、重金屬、病原體以及微生物。最常見的處理技術(shù)就是使用生物膜系統(tǒng)，洗滌水通過被細(xì)菌附著的基板進(jìn)行過濾，有機(jī)物質(zhì)的生物降解就在充氧條件下發(fā)生了。在氧氣供給良好的情況下，臭氣的產(chǎn)生可以被避免。這些系統(tǒng)范圍包括大面積的土地系統(tǒng)到強(qiáng)化的極需能量的應(yīng)用程序如滴流生物濾器和生物轉(zhuǎn)子。這些慢速的系統(tǒng)使用土壤生態(tài)系統(tǒng)來將污染水轉(zhuǎn)變成有價值的植物產(chǎn)品。他們應(yīng)當(dāng)衡量綠色植物的需求量。太多的水負(fù)荷對農(nóng)作物飽和是很不合理的，從另一方面來講過少的水量對植物影響也不好會導(dǎo)致其敏感。水的量取決于土壤水分蒸發(fā)蒸騰損失的速率，通常是每平米每天215升。澆灌整個區(qū)域可供選擇的方法有使用覆蓋物床來直接應(yīng)用于靠近農(nóng)作物和樹木。文獻(xiàn)中稍微有些概念混亂的“構(gòu)造濕地”經(jīng)常會出現(xiàn)。土壤過濾不應(yīng)當(dāng)當(dāng)作濕地來進(jìn)行設(shè)計或操作。對于有效率的過濾和曝氣，土壤沒有水飽和時很重要的。水應(yīng)當(dāng)從土壤的細(xì)小孔洞中過濾，將大氣孔依然留空且暴露在空氣中以便滿足好的空氣流通條件。合理設(shè)計和操作的垂直土壤過濾系統(tǒng)對懸浮固體以及有機(jī)化合物的去除率達(dá)到9099%，包括細(xì)菌和病毒在內(nèi)的病原體預(yù)期可以被減少95%。磷和重金屬去除是很重要的。磷的去除率預(yù)計在30%至95%之間，具體取決于土壤性質(zhì)、非飽水帶區(qū)域的深度以及污水負(fù)荷。氮由硝化和反硝化作用去除，通常在30%作用。