Water Technology and Management Division, CSIR-National Environmental Engineering Research Institute (NEERI), Nagpur, 440020, India.
Environ Sci Pollut Res Int. 2019 Jan;26(3):2079-2088. doi: 10.1007/s11356-017-0511-3. Epub 2017 Nov 12.
On-site sanitation is the most preferred mode of sanitation due to expensive off-site sanitation. The increasing population especially in the peri-urban areas has led to increasing use of on-site sanitation systems in India. However, the habitations in the vicinity of these systems do not have centralised water supply and are dependent on groundwater sources. However, there is concern about leaching of faecal coliforms and nitrate from the septic tanks to the underlying aquifer. The present study is attempted at two sites in the coastal city of Chennai where on-site sanitation is prevailing. The sample locations (16 nos.) are selected in such a way that groundwater sources are situated in the vicinity of on-site sanitation systems. The groundwater sources are the bore wells installed by the private agencies. It is observed that parameters considered key parameters to study the impact of the on-site sanitation systems, namely Na2, Cl, NO, faecal coliform and total dissolved solids, exceed the concentration limits recommended by the Bureau of Indian Standards. The piper diagram analysis identifies that the predominant cations and anions are respectively Na, and Cl, SO and HCO.The Gibbs plot shows ground water quality is dominated by the evaporation process in both the seasons. The Cl/HCO ratio in many samples confirms the seawater intrusion in the study area. Elevated concentrations of faecal coliforms in all the samples (16 nos.) confirm the significant amount of groundwater pollution from the on-site sanitation systems. It is desired that policy planners and implementation agencies should undertake detailed scientific and hydrogeological studies of the region in order to examine the feasibility of implementing on-site sanitation systems.
由于场外卫生设施费用昂贵，现场卫生是最受欢迎的卫生模式。特别是在城市周边地区，人口的增加导致印度越来越多地使用现场卫生系统。然而，这些系统附近的住所没有集中供水，而是依赖地下水源。然而，人们担心粪便大肠菌群和硝酸盐从化粪池渗透到地下含水层。本研究在钦奈沿海城市的两个地点进行，那里普遍存在现场卫生设施。选择了 16 个样本地点，以便地下水源位于现场卫生系统附近。地下水源是私人机构安装的水井。结果表明，被认为是研究现场卫生系统影响的关键参数，即 Na2、Cl、NO、粪便大肠菌群和总溶解固体，超过了印度标准局推荐的浓度限值。皮珀图分析确定主要阳离子和阴离子分别为 Na 和 Cl、SO 和 HCO。吉布斯图显示，在两个季节中，地下水质量均由蒸发过程主导。许多样本中的 Cl/HCO 比值证实了研究区域存在海水入侵。所有样本（16 个）中粪便大肠菌群浓度升高，证实了现场卫生系统对地下水的大量污染。希望政策制定者和实施机构应该对该地区进行详细的科学和水文地质研究，以检查实施现场卫生系统的可行性。
