Biodegradation rate constants in different NF/UF fractions of cork processing wastewaters

Abstract

Cork processing wastewater is an aqueous complex mixture of organic compounds that have been extracted from cork planks during the boiling process. These compounds, such as polysaccharides and polyphenols, have different biodegradability rates, which depend not only on the natureof the compound but also on the size of the compound. The aim of this study is to determine the biochemical oxygen demands (BOD) and biodegradationrate constants (k) for different cork wastewater fractions with different organic matter characteristics. These wastewater fractions were obtained using membrane separation processes, namely nanofiltration (NF) and ultrafiltration (UF). The nanofiltration and ultrafiltration membranes molecular weight cut-offs (MWCO) ranged from 0.125 to 91 kDa. The results obtained showed that the biodegradation rate constant for the cork processing wastewater was around 0.3 d(-1) and the k values for the permeates varied between 0.27-0.72 d(-1), being the lower values observed for permeates generated by the membranes with higher MWCO and the higher values observed for the permeates generated by the membranes with lower MWCO. These higher k values indicate that the biodegradable organic matter that is permeated by the membranes with tighter MWCO is more readily biodegradated.

Excessive greenhouse gas emissions from wastewater treatment plants by using the chemical oxygen demand standard

“…BOD is generally reported as 5-day BOD (BOD 5 ), 20-day BOD (BOD 20 ), and ultimate BOD (BOD u ) (Bernardo et al, 2011). The obtained dataset is BOD 5 .…”

Photoredox catalysis for environmental and chemical applications. A mechanistically-based approach.

“…However, the generated dark complex liquor contains suspended solids and also a high concentration of organic matter, see Table 2, [118,119], being polyphenolic compounds the most representative organic pollutants. [120,121] This kind of effluent exhibits low biodegradability, reducing the effectiveness of conventional biological treatments; [122][123][124] therefore the application of photocatalytic tools for their degradation offers good expectations. Under this context, the aim of the present chapter is to investigate the photocatalytic degradation of gallic acid (GA) and 2,4,6-trichloroanisole (TCA), Figure 10, two typical pollutants present in the cork industry wastewaters, using TPP + and TPTP + as organic photocatalysts, see Figure 9 and Table 1 in the Preamble of Part I.…”