Particle Size Distribution Analysis of Chemical Oxygen Demand Fractions with Different Biodegradation Characteristics in Black Water and Gray Water

Abstract

The study investigated the particle size distribution of major organic pollutants in black water and gray water fractions of domestic sewage. Particle size distribution was assessed by means of a filtration/ultrafiltration sequence together with laser diffraction. Emphasis was placed upon the correlation between the size distribution of chemical oxygen demand (COD) and its biodegradation characteristics obtained by respirometric analysis. Particle size distribution analysis provided specific fingerprints for COD, total organic carbon (TOC), carbohydrates, proteins, and color for black water and gray water: Aside from significant difference between COD contents, the more concentrated COD was predominantly in particulate form in black water, whereas soluble COD accounted for nearly 60% of the total in gray water. TOC and carbohydrate exhibited a similar pattern. Size distribution of particulate matter yielded different characteristics for the two fractions and indicated that settleable matter should be considered as a significant portion in assessing biodegradation. Particle size distribution of COD, although not directly related, gave an accurate image of biodegradation, indicating that particle size was basically the main parameter for differentiating and predicting major COD fractions with different biodegradation characteristics. It explained the dual hydrolysis mechanism associated with the black water based on the existence of a significant settleable COD fraction.

Remediation of suspended solids and turbidity by improved settling tank design in a small‐scale, free‐standing toilet system using recycled blackwater

“…In a separate series of filtration experiments, we found that ~50% of COD in blackwater from the preprocess tank was removed by a 0.7‐μm filter (the same filter size we use to determine TSS), suggesting that this fraction of COD is associated with suspended solids, in good agreement with previous reports (Levine et al, ; Hocaoglu and Orhon, ). We observed a 72% decrease in process liquid TSS with the enhanced settling system compared to the simple system (Fig.…”

“…Oxidant contact time (and thus energy) required for electrochemically produced oxidant inactivation of Escherichia coli in food processing waste waters increases with increased chemical oxygen demand (COD) of the process liquid (Lopez‐Galvez et al, ). As much as 60% of COD in concentrated blackwater is associated with particles large enough to potentially be removed by settling and/or practical filtration (Hocaoglu and Orhon, ). Therefore, we hypothesized that by improving the preprocess settling of blackwater in our system, we could both improve the appearance of the process liquid and potentially reduce the energy required for electrochemical disinfection by reducing particle‐associated COD.…”

A granular activated carbon/electrochemical hybrid system for onsite treatment and reuse of blackwater

“…(1985) reviewed particle size distributions (PSD) of COD in municipal wastewater streams and found that 34% of the COD was in readily settled particles. Another PSD study by Hocaoglu and Orhon (2013) of blackwater (a more similar waste stream to our own) reported that 62% of the COD was found in particles larger than 1.2 μm. These investigators also looked at the PSD within the settled fraction of their blackwater, and found that the settled fraction included particles significantly smaller than the generally accepted threshold for settling (100 μm), down to 10 μm, likely due to aggregation and co-precipitation with larger particles.…”

Effect of Operating Parameters on the Performance Evaluation of Benthic Microbial Fuel Cells Using Sediments from the Bay of Campeche, Mexico

“…In this study we identified that the marine water of the Bay of Campeche is at 1290 mg/L COD, the content of organic material being higher than that reported in the black and gray waters, where 1010 and 370 mg/L respectively were found, while that of domestic wastewater is at 440 mg/L [57]. However, for the use and disposal of water according to the Standard, a COD of 100-120 mg/L should be achieved, according to the SEMARNAT as reported in sanitation standards (NOM-001).…”