Downloaded by CENTRAL MICHIGAN UNIV on December 21, 2015 | http://pubs.acs.org Publication Date (Web): August 26, 2015 | doi: 10.1021/bk-2015-1198.ch007
Chapter 7
Identifying Knowledge Gaps in Assessing Implication of Engineered Nanomaterials on Wastewater Reuse Divya Singh and Arun Kumar* Department of Civil Engineering, Indian Institute of Technology, New Delhi, India *E-mail:
[email protected]; Phone: +91-11-2659-1166; Fax: +91-11-2658-1117
In recent years there has been increased usage of wastewater residuals (wastewater effluent and biosolids) in agriculture for irrigating crops and improving nutrient concentrations in soil. Engineered nanomaterials (ENMs) have been reported to be toxic to plants, aquatic species and human beings, hence, it becomes imperative to understand the effects of their presence in wastewater residuals on growth of edible plants and subsequently on human health. The objective of this study was to understand effect of use of engineered nanomaterials-contaminated wastewater effluent as irrigation water on growth of seeds and plants. To illustrate this, a hypothetical study was carried out for assessing risk due to consumption of tomato grown using ENM-contaminated wastewater. The analysis of published reports and literature data indicates the need of following future efforts: (1) Determination of occurrence of ENMs in wastewater effluents before it is used as irrigation water, (2) Determination of levels of ENMs in plants and edibles grown using wastewater effluents, and (3) Development of a health risk-based criteria for deciding treatment goals of ENMs in wastewater effluent before it can be used for irrigation activities. These efforts are needed to successfully reuse wastewater effluent as well as to protect human health.
© 2015 American Chemical Society In Emerging Micro-Pollutants in the Environment: Occurrence, Fate, and Distribution; Kurwadkar, Sudarshan, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.
Downloaded by CENTRAL MICHIGAN UNIV on December 21, 2015 | http://pubs.acs.org Publication Date (Web): August 26, 2015 | doi: 10.1021/bk-2015-1198.ch007
Introduction Agriculture sector demands almost 70% of the total water consumption, leading to burden on water source. According to the published reports, between years 2000-2030 developing countries are expected to expand irrigated area from 202 million hectares to 242 million hectares (1), which might result in an additional requirement of water for irrigation purposes. Currently around 7% of world’s agricultural land is irrigated using raw or partially treated wastewater directly or indirectly (2). In recent years, occurrence of engineered nanomaterials in wastewater have been reported (3). This information indicates the possibility of their exposure during use of wastewater for irrigation purposes. As these ENMs pose risks to health and toxicity to plants and aquatic species, it is important to know if use of wastewater effluent as irrigation water is appropriate for plant growth and for irrigating edible plants. Safe and well managed wastewater reuse is need of the hour, especially for countries with increasing demand of irrigation water. Table 1 shows parameters considered by various national and international agencies in determining the use of wastewater for irrigation purposes. From Table 1, it is clear that currently ENMs are not considered as one of the parameter for deciding the suitability of wastewater for irrigation purposes.
Table 1. Parameters considered in guidelines for selecting water for irrigation purposes
a
Agencies*
Parameters considered in Guidelines and their valuesa
FAO (1)
Total dissolved solids=450 mg/L, Na=3 me/L, Cl- =0.7-4 me/L, B=10 mg/L, N=
