Alexander Kathleen A, Godrej Adil
Fisheries and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA.
Center for African Resources: Animals, Communities and Land Use, Kasane, Botswana, South Africa.
Int J Environ Res Public Health. 2015 Nov 13;12(11):14529-40. doi: 10.3390/ijerph121114529.
Disposal of greywater is a neglected challenge facing rapidly growing human populations. Here, we define greywater as wastewater that originates from household activities (e.g., washing dishes, bathing, and laundry) but excludes inputs from the toilet. Pollutants in greywater can include both chemical and biological contaminates that can significantly impact human, animal, and environmental health under certain conditions. We evaluate greywater disposal practices in nonsewered, low-income residential areas in Kasane (264 dwellings/ha), Kazungula (100 du/ha), and Lesoma (99 du/ha) villages in Northern Botswana through household surveys (n = 30 per village). Traditional pit latrines were the dominant form of sanitation (69%, n = 90, 95% CI, 59%-79%) while 14% of households did not have access to onsite sanitation (95% CI 0%-22%). While greywater disposal practices varied across villages, respondents in all sites reported dumping greywater into the pit latrine. Frequency varied significantly across villages with the highest level reported in Kasane, where residential density was greatest (p < 0.014, χ² = 9.13, 61% (n = 23, 95% CI 41%-81%), Kazungula 41% (n = 22, 95% CI 20%-62%), Lesoma 13% (95% CI 0%-29%). Disposal of greywater in this manner was reported to limit contamination of the household compound and reduce odors, as well as pit latrine fecal levels. Some respondents reported being directed by local health authorities to dispose of greywater in this manner. Environmentally hazardous chemicals were also dumped directly into the pit latrine to reduce odors. With high household to pit latrine ratios particularly in rental properties (4.2 households, SD = 3.32, range = 15 units, average household size 5.3, SD = 4.4), these greywater and pit latrine management approaches can significantly alter hydraulic loading and leaching of chemicals, microorganisms, and parasites. This can dramatically expand the environmental footprint of pit latrines and greywater, increasing pollution of soil, ground, and surface water resources. Challenges in greywater disposal and pit latrines must be addressed with urgency as health behaviors directed at minimizing negative aspects may amplify the environmental impacts of both greywater and pit latrine excreta.
灰水的处理是快速增长的人口所面临的一个被忽视的挑战。在此，我们将灰水定义为源自家庭活动（如洗碗、洗澡和洗衣）的废水，但不包括来自马桶的污水。灰水中的污染物可能包括化学和生物污染物，在某些情况下会对人类、动物和环境健康产生重大影响。我们通过家庭调查（每个村庄30户）评估了博茨瓦纳北部卡萨内（264户/公顷）、卡宗古拉（100户/公顷）和莱索马（99户/公顷）村庄非下水道低收入居民区的灰水处理做法。传统坑式厕所是主要的卫生设施形式（69%，n = 90，95%置信区间，59%-79%），而14%的家庭没有现场卫生设施（95%置信区间0%-22%）。虽然不同村庄的灰水处理做法各不相同，但所有地点的受访者都报告将灰水倒入坑式厕所。不同村庄的频率差异显著，卡萨内报告的频率最高，那里的居住密度最大（p < 0.014，χ² = 9.13，61%（n = 23，95%置信区间41%-81%），卡宗古拉41%（n = 22，95%置信区间20%-62%），莱索马13%（95%置信区间0%-29%）。据报告，以这种方式处理灰水可限制家庭院落的污染并减少气味，以及坑式厕所的粪便量。一些受访者报告说，当地卫生当局指示他们以这种方式处理灰水。对环境有害的化学物质也被直接倒入坑式厕所以减少气味。由于家庭与坑式厕所的比例很高，特别是在出租房产中（4.2户，标准差 = 3.32，范围 = 15套，平均家庭规模5.3，标准差 = 4.4），这些灰水和坑式厕所管理方法会显著改变化学物质、微生物和寄生虫的水力负荷和淋溶。这会极大地扩大坑式厕所和灰水的环境足迹，增加土壤、地下水和地表水的污染。灰水处理和坑式厕所方面的挑战必须紧急加以解决，因为旨在尽量减少负面影响的健康行为可能会放大灰水和坑式厕所排泄物的环境影响。
