Speciation of heavy metals in electroplating industry sludge and wastewater residue using inductively coupled plasma

Abstract

ABSTRACT:The speciation of metals in environmental samples is a critical factor in assessing the potential environmental impacts, before their disposal. The distribution and speciation of toxic heavy metals in plating wastewater residues and sludge was investigated for four samples using sequential extraction method. Tessier method was used to fractionate the metal content into exchangeable, acid extractable, reducible and oxidizable fractions. Residual and total metal contents were determined in aqua regia digest. The extracts were analysed for metals using inductively coupled plasma -atomic emission spectrometry. The bioavailable fraction (exchangeable and acid extractable fractions) is comprised less than the other forms. The oxidisable and reducible forms are dominants for all the four samples studied. The major metal constitute in the samples is iron, the wastewater residue contains (12.3 and 7.4 g/Kg respectively on dry basis) and the sludge contains (31.5 and 41.6 g /Kg) respectively. Cr concentration is higher in wastewater residue of second electroplating industry. The descending order of the average total metal contents for these four samples were Fe > Cr > Sn > Zn >Cu > Ni > Mn > Pb > Cd > Ag. Based on the average of absolute values for the four samples the highest bioavailability order of metals is Cr (39 %) in wastewater residues and Zn (32 %) in sludge samples. Metal recovery was good, with < 10 % difference between the total metal recovered through the extractant steps and the total metal determined using aqua regia extract.

Seasonal Quality Assessment of Agricultural Soils along the Bank of Tungan Kawo Dam, Kontagora, Nigeria

“…Small amount of Cr associated with water soluble fraction are noticed in all the sites. This is similar to [34] where no Cr was detected in the first three fractions. According to them, the leaching of Cr to the environment from these samples may not occur readily.…”

“…Higher concentration of Zn in Fe-MnO fraction can be attributed to diffusion mechanism [43]. This metal can be release into the environment under extremely reducible conditions [34].…”

Effects of Natural Zeolites on Bioavailability and Leachability of Heavy Metals in the Composting Process of Biodegradable Wastes

“…The total metal contents are increased in the final compost due to the reduction of organic matter and release of CO 2 during the mineralization process [4]. The total metal concentration found after strong acid digestion of final compost is useful as an overall pollution indicator but provides no useful information about the bioavailable fractions and chemical speciation of metals [5,6].…”

“…The total concentration of heavy metals measured from compost samples digested with strong acids can indicate the possibility of metal pollution, but cannot specify information related to the bioavailability of heavy metals [5,6]. The bioavailability of any element specifies the fraction of the element's total content that is easily soluble in an aqueous system, and hence is freely available to plants and soil microorganisms.…”

Remoção De Metais Utilizando Biossurfactante Produzido Pela Pseudomonas Aeruginosa Atcc 10145

“…Um exemplo de acidente ocorrido, foi o de 2015, no Brasil, em que uma mineradora, foi responsável pela liberação de elevadas concentrações de metais pesados como ferro e manganês em águas superficiais do país (MAITY et al, 2013, SEGURA et al, 2016 As características de toxicidade, abundância e não biodegradabilidade dos metais pesados, faz com que esses compostos, se lançados em águas superficiais, ocasionem efeitos nocivos nos organismos vivos, ao bioacumularem ao longo da cadeia alimentar, fazendo com que esses compostos sejam removidos desses ambientes. Dentre as tecnologias desenvolvidas para a remoção de metais pesados, destaca-se o processo de remediação, que utiliza de compostos de origem microbiana para o tratamento dos ambientes contaminados (VENKATESWARAN et al, 2007, BELKHIRI et al, 2017, COMBY et al, 2014, KANOUN-BOULE et al, 2009). …”