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Flame Retardants and the Environment
Published in Asim Kumar Roy Choudhury, Flame Retardants for Textile Materials, 2020
There is no data in the literature on the toxicological, immunological, neurological, or carcinogenic and mutagenic effects of oral exposure to ammonium polyphosphate (APP), ammonium ions, or polyphosphates. The only documented negative environmental effect of APPs is the algal toxicity. As a result of low environmental risks, APPs and MPP (melamine polyphosphate) could represent a good alternative to brominated FRs (Horrocks, 2001).
Phytoremediation capabilities of Salvinia molesta, water hyacinth, water lettuce, and duckweed to reduce phosphorus in rice mill wastewater
Published in International Journal of Phytoremediation, 2020
In this paper, phosphorus reduction efficiency of four free floating aquatic plants, namely water hyacinth, water lettuce, salvinia, and duckweed, is compared. Phosphorus is a macronutrient essential for floral life, and it is found in various forms in water: (a) dissolved inorganic phosphorus (DIP), (b) particulate inorganic phosphorus, (c) dissolved organic phosphorus, and (d) particulate organic phosphorus. DIP is the most bio-absorbable form of phosphorus. All the other forms must be first converted into DIP and then utilized by aquatic plants (Ready et al. 1999). In a plant body, phosphorus is accumulated as polyphosphate, which is acid soluble and used for plant metabolism and for the production of deoxyribonucleic acid (DNA) and protein. Insoluble phosphorus stored in plant biomass are used by plants during a scarcity of phosphorus in the environment. Excess phosphorus concentration in water leads to toxic algal bloom, which causes low oxygen levels, fish mortality, and loss of aquatic biodiversity. Phosphorus is eliminated through various mechanisms such as direct uptake by plants, assimilation by microbes, filtration by rhizosphere, adsorption on roots, and precipitation with the help of metal ions. Phosphorus removal depends on the growth rate and phosphorus content of plants. It is faster when the phosphorus concentration of water is lower than a specific limit. Water lettuce can tolerate up to 50 mg/l phosphate, and the accumulation rate was 6.12 ± 0.95 mg/g dry weight of plant after 35 days of investigation under greenhouse condition (Ready et al. 1999). A summary of phosphorus removal by aquatic plants and their system details are given in Table 1. Although studies on contamination removal from wastewater are numerous, only a few studies have been performed on parboiled rice mill wastewater. Therefore, we performed a study on rice mill wastewater and investigated the performance of each aquatic plant compared with the control and with each other.