Monitoring of total metal concentration in sludge samples: case study for the mechanical-biological wastewater treatment plant in Velika Gorica, Croatia.
Sci Total Environ
; 447: 17-24, 2013 Mar 01.
Article
em En
| MEDLINE
| ID: mdl-23376512
ABSTRACT
In this paper, monitoring of total metal concentration in sludge samples from wastewater treatment process is elaborated. The presented results summarize the analyses of sludge samples in a period from 2008 to 2012. Possible sources of pollutions are given. Primarily, waste solid samples were collected from different pretreatment steps:
(A) coarse grid, (B) fine grid and (C) aerated sand grease grid. Samples of A and B followed a repeatable pattern in 2008 and 2010. According to the results from 2008, samples of C contained measurable concentration of the following metals (mg/kg dry matter) Zn (21), Ni (1.05) and Ba (14.9). Several types of sludge samples were analyzed fresh raw sludge (PS; 6-12 hour old), the sludge from the digester for anaerobic sludge treatment (DS; 48-72 hour old), samples from lagoons where the sludge is temporarily deposited (DOS and DOSold; 30-120 days) and sludge samples from agricultural areas (AA; aged over 180 days). Additionally, samples of dehydrated sludge (DEHS and DEHSold; 90-180 days) were collected upon construction of equipment for sludge dehydration in 2011. An analysis of total metal concentrations for Cu, Zn, Cr, Pb, Ni, Hg, Cd, Ba, As, Se, Sb, Co, Mo, Fe and Mn was performed by flame atomic absorption spectrometry (FAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). The most recent results (year 2011) indicated a high concentration of heavy metals in PS samples, exceeding the MCLs (mg/kg dry matter) Cu (2122), Zn (5945), Hg (13.67) and Cd (6.29). In 2012 (until July), only a concentration of Cu exceeded MCL (928.75 and 1230.5 in DS and DEHS, respectively). A composition of sludge was variable through time, offering the limited possibility for future prediction. The sludge is being considered as a hazardous waste and a subject of discussion regarding disposal.
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Base de dados:
MEDLINE
Assunto principal:
Esgotos
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Águas Residuárias
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Metais
Tipo de estudo:
Prognostic_studies
País/Região como assunto:
Europa
Idioma:
En
Revista:
Sci Total Environ
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Croácia