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The tremendous increase in the production and consumption of titanium dioxide (TiO2) nanoparticles (NPs) in numerous industrial products and applications has augmented the need to understand their role in wastewater treatment technologies. Likewise, the deleterious effects of wastewater on the environment and natural resources have compelled researchers to find out most suitable, economical and environment friendly approaches for its treatment. In this context, the use of TiO2 NPs as the representative of photocatalytic technology for industrial wastewater treatment is coming to the horizon. For centuries, the use of industrial wastewater to feed agriculture land has been a common practice across the globe and the sewage sludge generated from wastewater treatment plants is also used as fertilizer in agricultural soils. Therefore, it is necessary to be aware of possible exposure pathways of these NPs, especially in the perspective of wastewater treatment and their impacts on the agro-environment. This review highlights the potential exposure route of TiO2 NPs from industrial applications to wastewater treatment and its impacts on the agro-environment. Key elements of the review present the recent developments of TiO2 NPs in two main sectors including wastewater treatment and the agro-environment along with their potential exposure pathways. Furthermore, the direct exposure routes of these NPs from production to end-user consumption until their end phase needs to be studied in detail and optimization of their suitable applications and controlled use to ensure environmental safety.

Nanowaste is defined as waste derived from materials with at least one dimension in the 1–100 nm range. The nanomaterials containing products are considered as “nanoproducts” and they can lead to the development of nanomaterial-containing waste, also termed as “nanowaste”. The increased production and consumption of these engineered nanomaterials (ENMs) and nanoproducts that generate enormous amounts of nanowaste have raised serious concerns about their fate, behavior, and ultimate disposal in the environment. It is of the utmost importance that nanowaste is disposed of in an appropriate manner to avoid an adverse impact on human health and the environment. The unique properties of ENMs, combined with an inadequate understanding of appropriate treatment techniques for many forms of nanowaste, makes nanowaste disposal a complex task. Presently, there is a lack of available information on the optimized standards for identifying, monitoring, and managing nanowaste. Therefore, this review highlights concerns about nanowaste as future waste that need to be addressed. The review focuses on ENMs waste (in the form of NP, nanotubes, nanowires, and quantum dots) generated from the manufacture of a wide variety of nanoproducts that end up as nanowaste and adversely affect the environment. Furthermore, the review considers different types of ENMs in waste streams and environmental compartments (i.e., soil, water, and air). Detailed studies are still required to identify data gaps and implement strategies to remove and control this future waste.

Nutrient management is always a great concern for better crop production. The optimized use of nutrients plays a key role in sustainable crop production, which is a major global challenge as it depends mainly on synthetic fertilizers. A novel fertilizer approach is required that can boost agricultural system production while being more ecologically friendly than synthetic fertilizers. As nanotechnology has left no field untouched, including agriculture, by its scientific innovations. The use of nanofertilizers in agriculture is in the early stage of development, but they appear to have significant potential in different ways, such as increased nutrient-use efficiency, the slow release of nutrients to prevent nutrient loss, targeted delivery, improved abiotic stress tolerance, etc. This review summarizes the current knowledge on various developments in the design and formulation of nanoparticles used as nanofertilizers, their types, their mode of application, and their potential impacts on agricultural crops. The main emphasis is given on the potential benefits of nanofertilizers, and we highlight the current limitations and future challenges related to the wide-scale application before field applications. In particular, the unprecedent release of these nanomaterials into the environment may jeopardize human health and the ecosystem. As the green revolution has occurred, the production of food grains has increased at the cost of the disproportionate use of synthetic fertilizers and pesticides, which have severely damaged our ecosystem. We need to make sure that the use of these nanofertilizers reduces environmental damage, rather than increasing it. Therefore, future studies should also check the environmental risks associated with these nanofertilizers, if there are any; moreover, it should focus on green manufactured and biosynthesized nanofertilizers, as well as their safety, bioavailability, and toxicity issues, to safeguard their application for sustainable agriculture environments.