Effect of adding alum sludge from water treatment plant on sewage sludge dewatering

Li, Jun; Liu, Liu; Liu, Jun; Ma, Ting; Yan, Aibin; Ni, Yajuan

doi:10.1016/j.jece.2015.07.021

Cited by 48 publications

(9 citation statements)

References 35 publications

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“…This solid fraction comprises predominantly metal salt coagulant, organic constituents and other particulates from the catchment. Owing to the high volume of waste produced, water treatment works use various methods to dewater the sludge retrieved from settling beds to between 17 and 35% solids in order to make its transport and disposal more economically viable, whereby the extent of dewatering is governed by the cost benefit (Li et al, 2016).…”

Section: Water Treatment Residual Characteristicsmentioning

confidence: 99%

Reusing Fe water treatment residual as a soil amendment to improve physical function and flood resilience

Kerr

Johnson

Toll

2021

Preprint

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Abstract. Soil degradation is a global challenge that is intrinsically linked to climate change and food security. Soil degradation has many causes, but all degraded soils suffer from poor soil structure. The UN’s Sustainable Development Goals 12, 13 and 15 strive towards responsible consumption and production, building a zero-waste circular economy, achieving net zero by 2030 and reversing land degradation to protect one of our most valuable assets, soil. Global efforts to stop and even reverse soil degradation require sources of both organic and inorganic materials to rebuild soil structure. The increasing global production of water treatment residual (WTR), an organo-mineral waste product from clean water treatment, means that the sustainable reuse of this waste provides a potential timely opportunity. Recycling or reuse of WTR to land is commonplace across the world but is subject to limitations based on the chemical properties of the material. Very little work has focused on the physical impacts of Fe-WTR application and its potential to rebuild soil structure particularly improving its ability to hold water and resist the effects of flooding. This paper presents novel research in which the use of Fe-WTR and Fe-WTR/compost [1:1] co-amendment has shown to be beneficial for a soil’s water retention, permeability, volume change, and strength properties. Application rates of WTR were 10 and 30 % by dry mass. Compared to the control soil, co-amended samples have 5.7 times the hydraulic conductivity (570 % improvement), 54 % higher shear strength and 25 % greater saturated water content. Single WTR amendment had 26 times the saturated hydraulic conductivity (2600 % improvement), 129 % higher shear strength and 13.7 % greater saturated water content. Data indicates that WTR can be added as a single amendment to significantly improve soil physical characteristics where shear strength and hydraulic conductivity are the most important factors in application. Although the co-application of Fe-WTR with compost provides a lesser improvement in shear strength and hydraulic conductivity compared to single WTR amendment, the co-amendment has the best water retention properties and provides supplementary organic content, which is beneficial for environmental applications where the soil health (i.e. ability to sustain ecosystem functions and support plants) is critical. We develop the term ‘flood holding capacity’ to holistically describe the physical ecosystem services that soil delivers, which incorporates not only the gravimetric water content but the extra water storage potential due to increases in volume that occur in organic rich soils, the transmissivity of the soil (hydraulic conductivity) and the shear strength of a soil, which determines how well a soil will resist the erosive forces of water movement.

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Section: Water Treatment Residual Characteristicsmentioning

confidence: 99%

Reusing Fe water treatment residual as a soil amendment to improve physical function and flood resilience

Kerr

Johnson

Toll

2021

Preprint

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“…The mechanisms were likely driven by a large portion of insoluble aluminum hydroxides in the liquid and/or solid phase of alum sludge acting as a coagulant in coagulation/flocculation by particle-particle bridging and surface charge neutralization processes (Chu 2001). Additionally, the solid phase of alum sludge could act as the skeleton builders as well during the conditioning process (Basibuyuk and Kalat 2004) Alum sludge can also act as a skeleton builder or filter aid (Li et al 2016), which can effectively reduce sludge compressibility. This helps the sludge cake form a permeable and rigid structure while maintaining porosity, even under a high compression pressure.…”

Section: Optimal Mixing Ratio Of the Sludgesmentioning

confidence: 99%

Integrating alum sludge with waste-activated sludge in co-conditioning and dewatering: a case study of a city in south France

Ren

Lyczko

Zhao

et al. 2020

Environ Sci Pollut Res

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The unique geographical location of waterworks and wastewater treatment plant (WWTP) in Graulhet (France) profited the environmental resource integration and "Circular Economy." Alum sludge from a local waterworks was introduced to co-conditioning and dewatering with waste-activated sludge from a nearby WWTP to examine the role of the alum sludge in improving the dewaterability of the mixed sludge. Experiments demonstrated that the optimal mixing ratio was 1:1 (waste-activated sludge/alum sludge, v/v). Alum sludge has been shown to beneficially enhance mixed sludge dewaterability, by decreasing both the specific resistance to filtration (SRF) and the capillary suction time (CST). Moreover, the optimal polymer (Sueprfloc-492HMW) dose for the mixed sludge (mix ratio 1:1) was 200mg/l, highlighting a huge savings (14 times) in polymer addition without alum sludge involvement. In addition, cost-effective analysis of its potential full-scale application has demonstrated that the initial investment could be returned in 11years. The co-conditioning and dewatering strategy can be viewed as a "win-win" strategy for the Graulhet, France water and wastewater industry.

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“…Behaviors of EPS in flocculation and dewatering of activated sludge together with EPS characteristics have been discussed comprehensively in several other studies [7,8,9,10,11]. EPS may contain up to 95% of moisture and are closely linked to bound water which is difficult for mechanical dewatering to release [12,13,14,15]. EPS can be found in two forms, namely soluble and bound EPS, which can be further subdivided into loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS).…”

Section: Introductionmentioning

confidence: 99%

Deleterious effects of soluble extracellular polymeric substances on polyacrylamide demand for conditioning of anaerobically digested sludge

Nguyễn

Bustamante

et al. 2019

Journal of Environmental Chemical Engineering

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High polyacrylamide (polymer) demand for conditioning of sludge, especially anaerobically digested sludge (ADS), is a major issue for the water industry. Currently, this problem is being investigated and the reasons for doing so are varied. It has been demonstrated that excess amounts of soluble extracellular polymeric substances (EPS) can lead to high polymer demand for conditioning. This study developed a simple and unique yet effective method for quantifying the contribution of soluble EPS to conditioning polymer demand. It did this by measuring absorbance at 191.5 nm wavelength of the supernatant derived from conditioned ADS. Experimental results confirmed that approximately 87 wt% of soluble EPS interacted with polyacrylamides during the conditioning process. Furthermore, they revealed that a specified amount of soluble EPS could not be removed by polymer flocculation despite high polymer dosage. This study concluded that about 86 wt% of the polyacrylamide used for conditioning was consumed solely by soluble EPS. These results confirm the important role of reducing this EPS fraction in ADS in order to curtail significant chemical costs for sludge conditioning and dewatering.

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Effect of adding alum sludge from water treatment plant on sewage sludge dewatering

Cited by 48 publications

References 35 publications

Reusing Fe water treatment residual as a soil amendment to improve physical function and flood resilience

Reusing Fe water treatment residual as a soil amendment to improve physical function and flood resilience

Integrating alum sludge with waste-activated sludge in co-conditioning and dewatering: a case study of a city in south France

Deleterious effects of soluble extracellular polymeric substances on polyacrylamide demand for conditioning of anaerobically digested sludge

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