Nawaz M.S.,Institute of Environmental Science and Engineering IESE |
Khan S.J.,National University of Sciences and Technology
Journal of the Chemical Society of Pakistan | Year: 2013
Textile wastewater contains organics and color dyes which need to be treated before discharging into receiving water bodies. Sequencing batch reactor (SBR) is proved promising against textile wastewater due to its high organic and nutrient removal efficiencies. In this study the influence of variable hydraulic retention time (HRT) on the performance of SBR in treating combined textile and domestic wastewater was evaluated. Six SBRs were operated in parallel at 12 and 8 hrs HRTs respectively, three for synthetic and three for real textile plus domestic wastewater. SBRs were operated at constant temperature 25 ± 1 °C and pH 7 ± 1 to avoid seasonal effects. The biological oxygen demand (BOD) removal efficiency was consistent at 73% while, total suspended solids (TSS) removal efficiency increased from 52 to 63% in SBRs with decrease in HRT from 12 to 8 hrs. The organic loading rate (OLR) increased from 0.45 to 0.68 Kg/m3/d, SVI decreased from 94 to 84 mL/g and chemical oxygen demand (COD) removal efficiency increased in real waste water (RWW) SBRs from 59 to 63% with decrease in HRT from 12 to 8 hrs. Low COD removal at 12 hr HRT can be attributed to poor settling characteristics of sludge due to possible filamentous growth at low F/M (0.03) and greater SRT (28 days) as compared to 8 hr HRT condition, where F/M was 0.05 and SRT of 20 days.
Saba B.,Institute of Environmental Science and Engineering IESE |
Hashmi I.,Institute of Environmental Science and Engineering IESE |
Awan M.A.,Institute of Environmental Science and Engineering IESE |
Nasir H.,National University of Sciences and Technology |
Khan S.J.,Institute of Environmental Science and Engineering IESE
Desalination and Water Treatment | Year: 2012
In this study, the distribution, toxicity level, and relationship of polycyclic aromatic hydrocarbons (PAHs) with total organic content (TOC) have been investigated using surface soil and ground water samples from an area adjacent to petrochemical plant in Pakistan. Six PAHs, naphthalene, acenaphthene, phenanthrene, anthracene, flouranthene, and chrysene, were selected from the 16 Environment Protection Agency priority pollutants list. σPAHs range from 2,700 to 4,443 lg/g (average: 3,672 ± 592 lg/g) in soil and 201-1,634 ng/L (average: 763 ± 377 ng/L) in water. The compositional profile of PAHs revealed that low molecular weight 3-4 ring PAHs were predominant. The ratios of phenanthrene/anthracene reflected the pyrogenic origin of PAHs. The relationship of PAHs with TOC has also been investigated and a positive correlation was observed between RPAHs and TOC. This indicates that partitioned in organic matter may be the possible source of PAHs in water. An assessment using widely cited guidelines indicates that water samples do not pose biological impact, while soil can pose a threat of lung cancer. © 2012 Desalination Publications. All rights reserved.