Feasibility Study of Chromium Removal from Paint Sludge with Biological Sludge, Using Vermicompost by Eisenia fetida (Case Study: Saipa Automotive Industry)

Abstract

Background: During the paint spraying process in the automotive industry, a variety of wastes, including a large amount of paint sludge is produced, which contains a variety of hazardous substances, such as BTEX and heavy metals. The aim of the present study was vermicomposting of paint sludge with sewage sludge and Eisenia fetida as earthworm spices for reduction of heavy metals. Objectives: Vermicomposting process employing earthworms is increasingly being used for conversion of both sewage and some industrial wastes to reduced heavy metals and volatile solid content in bulk of solid wastes. Therefore, in this study, feasibility of chromium removal from paint sludge by using Eisenia fetida worms was investigated. Methods: In this study, the quantitative and qualitative characteristics of paint and biological sewage sludge waste were determined in terms of Cr +6 , moisture content, nitrogen and carbon, C/N ratio, pH and temperature. Then the paint sludge was mixed in various proportions with the thickening biological sewage sludge of Saipa's sewage treatment plant. The decomposition time for the vermicompost samples for each run was 90 days. In order to analyze various parameters, including Cr +6 and volatile solids reduction, sampling from each pilot was performed on 1, 15, 30, 50, 70 and 90 days. The Cr +6 measurements were performed using the AASM method. The paint sludge and sewage sludge were mixed in different ratios. After the mixing, 500 adult Eisenia fetida earthworms were introduced to each box. Results: The results showed that the optimum removal rate for Cr +6 was found in the mixing ratio of 6 kg of biological sludge with 600 g of paint sludge and in this ratio, the amount of Cr +6 concentration fell from 6 mg/kg to less than 0.2 mg/kg in 90 days. In addition, in the same ratio of sludge mixing, the C/N ratio ranged from about 27 on the first day to 14.3 on day 90 and the pH decreased from 7.8 on the first day to 7.3 on the 90 th day. Volatile solids decreased from 80.4% on the first day to 37% on the 90 th day. Conclusions: Vermicomposting is a good alternative for treating paint sludge with biological sludge, and is advantageous for reduction of pollutants purposes. Research was carried out on bioavailability of heavy metals such as Cr +6 during vermicomposting for 90 days using Eisenia fetida earthworms. Finally, the results showed that, Eisenia fetida could eliminate Cr +6 in low levels.

Heavy Metals and Probabilistic Risk Assessment via Pheretima (a Traditional Chinese Medicine) Consumption in China

“…Studies have indicated that Cr (VI) is cytotoxic and able to induce DNA-damaging effects such as chromosomal abnormalities ( Patlolla et al, 2008 ), DNA strand breaks, DNA fragmentation, and oxidative stress in Sprague–Dawley rats and human liver carcinoma cells ( Patlolla et al, 2009 ; Kumar et al, 2013 ). Earthworms can bioaccumulate high concentrations of metals, including heavy metals, in their tissues without affecting their physiology, so they could particularly ingest and enrich extremely high amounts of heavy metals ( Ghomi Avili et al, 2018 ). As a consequence, the aforementioned reasons may cause excessive metal concentration in Pheretima and then pose health risk to the exposed population.…”

Treatment of PCBs Contaminated Soil Via Aerobic Vermicomposting Process Amended with Biological Sewage Sludge

“…He et al (9) also investigated the effect of earthworms on 500 µg/kg PCB congeners. The novelty of our method is that earthworms were added to a mixture of contaminated soil and biological sludge to eliminate higher concentrations of PCBs compared to previous methods (10) 12) examined the removal of petroleum hydrocarbons from contaminated soil using the vermicomposting process. Also the vermicomposting method, in which biological sewage sludge is used to feed worms and microorganisms, has not been studied to refine soil contaminated with power plant Ascarel oil, and can be considered as an important and innovative step.…”

Isolation and Identification of Resistant Microorganisms from Automotive Paint Sludge

“…Their results showed that carbon and nitrogen, organic matter and BTEX, nickel and tin, the ratio decreased (11). Ghomi Avili et al (12) investigated chromium removal from automotive paint sludge using biological sludge and Eisenia fetida worms. The results showed that the Cr +6 concentration fell from 6 mg/kg to less than 0.2 mg/kg, pH decreased from 7.8 to 7.3, volatile solids decreased from 80.4% to 37%, and the C/N ratio decreased from about 27 to 14.3 after 90 days.…”