Influence of organic and inorganic flocculants on the formation of PCDD/Fs during sewage sludge incineration

Abstract

Flocculants are widely used to improve the properties of sludge dewatering in industrial wastewater treatment. However, there have been no studies conducted on the influence of flocculants on the formation of polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) during sewage sludge incineration. This paper selected three typical kinds of flocculants, including polyacrylamide (PAM), poly-ferric chloride (PFC), and polyaluminum chloride (PAC) flocculant, to study their influences on the formation of PCDD/Fs during sewage sludge incineration. The results indicated that PAM flocculant, which is an organic flocculant, inhibited the formation of PCDD/Fs in sewage sludge incineration, while inorganic flocculant, such as PFC and PAC flocculant, promoted the formation. The most probable explanation is that the amino content in the PAM flocculant acted as an inhibitor in the formation of PCDD/Fs, while the chlorine content, especially the metal catalyst in the PFC and PAC flocculants, increased the formation rate. The addition of flocculants nearly did not change the distribution of PCDD/F homologues. The PCDFs contributed the most toxic equivalent (TEQ) value, especially 2, 3, 4, 7, 8-PeCDF. Therefore, the use of inorganic flocculants in industrial wastewater treatment should be further assessed and possibly needs to be strictly regulated if the sludge is incinerated. From this aspect, a priority to the use of organic flocculants should be given.

Municipal solid waste incineration in China and the issue of acidification: A review

“…Practical measures include: steady feeding after thorough mixing, while respecting the 3Ts (temperature, time, and turbulence) essential for obtaining complete combustion (Buekens and Huang, 1998 -compounds, N-compounds, or basiccompounds (Griffin, 1986;Lin et al, 2015a;Lin et al, 2015b;Ruegg and Sigg, 1992). Owing to memory effects, it is essential to maintain well-controlled combustion at all times.…”

“…Owing to memory effects, it is essential to maintain well-controlled combustion at all times. Practical measures include: steady feeding after thorough mixing, while respecting the 3Ts (temperature, time, and turbulence) essential for obtaining complete combustion (Buekens and Huang, 1998 S-compounds, N-compounds, or basiccompounds (Griffin, 1986;Lin et al, 2015a;Lin et al, 2015b;Ruegg and Sigg, 1992). • • End-of-pipe solutions basically include adsorption by solid sorbents and destruction by catalytic oxidation during DeNOx (Hiraoka et al, 1989).…”

Synthesis, Characterization, and Sludge Dewaterability Evaluation of the Chitosan-Based Flocculant CCPAD

“…Improperly handled sludge would cause serious secondary pollution. The treatment and disposal of sludge have become an important step in sewage treatment such that sludge treatment is also an important standard for evaluating the quality of sewage treatment [4]. The disposal of sludge has certain requirements for the moisture content of the sludge [5].…”

Advancement in Sewage Sludge Dewatering with Hydrate Crystal Phase Change: Unveiling the Micro-Moisture Migration and Dewaterability Mechanisms

“…However, these combustion-based technologies require the water content below 60 wt %. , Massive chemical additives such as polymeric aluminum chloride or ferric chloride are added to the sludge to meet the water content limitation. These chemicals could reduce the calorific value of sludge, hindering its thermal utilization as a resource for sludge incineration and the chlorine introduced by commonly used chemical additives may increase the risk of dioxin formation during incineration of dewatered sludge. , …”