Agriculture Reference
In-Depth Information
That is, the generated agricultural wastewater has also exacerbated the contradic-
tion between supply and demand of water resources.
Due to the complexity of the agroecosystem, traditional urban sewage treatment
technologies, such as activated sludge process, anaerobic fermentation, and
constructed wetland, are difficult to use in the agricultural system. In particular,
for persistent organic pollutants such as pesticides and veterinary drugs, conven-
tional water treatment technology is even more difficult to play a role.
In recent years, more and more attention has been paid to nano-materials due to
their small surface area and high reactivity. However, because of the high cost of
nanometer materials and high technical requirements, there are only a few appli-
cations in agro-environmental protection field.
In this chapter, we selected three kinds of nano-materials (nano-iron, nano-TiO
2
,
and nanofiltration) with higher technological maturity and good promotion pros-
pects from numerous nanotechnologies and applied them for fertilizer-polluted
groundwater, livestock wastewater, and irrigation water for greenhouse vegetables,
respectively. The emphasis is placed on the nature, scope, and pollutant removal
capabilities of these nano-materials.
With the development of industry and agriculture, nitrate (NO
3
) detection
frequency and concentration in groundwater is increasing in many countries and
has become a very serious environmental issue. In the early 1960s, the USA and
Europe had reported NO
3
pollution due to chemical nitrogen fertilizer. Moreover,
the results of continuous monitoring in Palestine between 1982 and 2004 revealed
that the NO
3
content of groundwater in the West Bank region showed an increas-
ing trend (Anayah and Almasri
2009
). Even in countries with the most developed
economy and technology, such as the USA, NO
3
pollution is serious. The US
national water quality survey indicated that among the 1992 surveyed wells, 3 %
contained NO
3
content exceeding the standard limit, and the proportion was over
25 % in high-pollution risk areas (Nolan et al.
1997
).
Numerous studies have shown that excessive use of agricultural nitrogen ferti-
lizer is one of the main causes of the increase in the NO
3
concentration in
groundwater. As nitrogen cannot be completely absorbed by crops and because
soil colloids cannot adsorb monovalent NO
3
ions, when a large quantity of
nitrogen fertilizer or manure is applied to farmland, the NO
3
in the soil easily
penetrates into groundwater through rainfall and irrigation. In some developing
countries, such as China, India, and Brazil, which have very large increasing
populations, there is a need to increase food production in the next 10 years by
using more quantities of nitrogen fertilizer, which will definitely result in serious
NO
3
pollution of groundwater.
