Improvement of Co-Composting by a combined pretreatment Ozonation/Ultrasonic process in stabilization of raw activated sludge

Hamideh Dastpak,Mahdi Farzadkia,Ahmad Jonidi Jafari,Hasan Pasalari,Mitra Gholami

doi:10.1038/s41598-020-58054-y

Hamideh Dastpak, Mahdi Farzadkia + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-58054-y

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Journal: Scientific Reports	Publication Date: Jan 23, 2020
Citations: 14	License type: open-access

Affiliation: Iran University of Medical Sciences

Abstract

The enhancement of composting technology to stabilize sludge pretreated by ozonation and ultrasonic was tested for 35 days. Secondary sludge produced by biological process are characterized with endogenous residue and inert solid matter which inhibit fully degrade bacterial cell walls. The composting process was performed with sludge pretreated with ozonatian and ultrasonics and green waste in a ratio of 2:1. The composting characteristics was evaluated for different physico-chemical and microbiological parameters in five different reactors. A high degree of composting quality was achieved with respect to significant reduction in volatile solids (VS) (32%), total organic carbon (TOC) (35.0%), C/N ratio (23.74), total coliform (TC) (168) along with the substantial increase in availability of nutrients like N (1.2%) and P (8.77%). High removal efficiency of TC and Fecal Coliform (FC) were observed in composting results, where simultaneous ultrasonic and ozonation were considered as primary-stabilization process. Therefore, applying integrated ultrasonic/ozonation with composting system for sludge stabilization is potentially useful technology in sustainable land restoration practices to meet standards and produce soil conditioner.

Highlights

Overproduction of sewage sludge (SS), as an inevitable byproduct from activated sludge process, has currently led to use of inappropriate disposal practices[1]
The results indicated that ultrasonic pretreatment favors sludge disintegration and improve the biodegradability process
The sludge characteristics after applying simultaneous ozone and ultrasonic for primary-stabilization of raw sludge show that these parameters are in average values between values of ozonation and ultrasonic alone, except volatile solids (VS) (77.97%), total organic carbon (TOC) (43.31%), and C/N (39.37%) ratio which had higher values compared to separate application of ozone and ultrasonic

Summary

Introduction

Overproduction of sewage sludge (SS), as an inevitable byproduct from activated sludge process, has currently led to use of inappropriate disposal practices[1]. A variety of chemical and physical treatment techniques have been applied to enhance lysis and disintegration of sewage sludge, including thermal hydrolysis[12], mechanical disintegration[13], freezing[14], ultrasonic process[15,16] and ozonation[17,18]. Ultrasonic is currently recognized as highly effective, environmentally friendly and cost-effective pretreatment method in sewage sludge management[16,21]. This process produces extreme condition, so-called, “hot-spots” with high temperature and pressure (5000 K, 1000 atm)[22]. Additional aim of present research was to examine the ability of co-composting process in stabilization of raw activated sludge pretreated by ultrasonic and ozonation separately and simultaneously were evaluated

Methods

Results

Conclusion