Phosphate fertilizer value of heat treated sewage sludge ash

This study focuses on the question whether heat treated sewage sludge ashes are more favourable as fertilizers than untreated sewage sludge ashes (USSA) and whether their fertilization effects are comparable with commercial triple superphosphate (TSP). In a pot experiment, maize was fertilized either with one of three heat treated and Na-, Ca- and Si-compounds amended sewage sludge ashes (two glown phosphates, steel mill slag + sewage sludge ash) or USSA or TSP as control. Fertilization with USSA did not increase the biomass yield and the P uptake of maize in comparison to the P0 treatment (7.25 resp. 8.35 g dry matter/pot). Fertilization with heat treated sewage sludge ashes and TSP resulted in significantly higher yields and plant P uptakes which are on average eight times higher than treatment with USSA and P0 control. Biomass yields and P uptake of maize after fertilization with heat treated sewage sludge ashes are not significantly different from those after TSP fertilization. The main P compound in USSA is Ca3(PO4)2. By heat treatment and amendment with different sodium, calcium, sulphur and silicon containing additives or steel mill converter slag, Ca3(PO4)2 is converted to Ca- and Na-silico-phosphates, which have a higher water solubility than Ca3(PO4)2. This increased solubility is responsible for the high plant availability of this phosphates.

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Critical Evaluation of the Agronomic Effectiveness of Recovered Phosphate Fertilizer Produced From Incinerated Sewage Sludge Ash

10.21203/rs.3.rs-709653/v1 ◽

2021 ◽

Author(s):

Le FANG ◽

Qiming Wang ◽

Jiang-shan Li ◽

Chi Sun Poon

Keyword(s):

Sewage Sludge ◽

Plant Growth ◽

Critical Evaluation ◽

Phosphate Fertilizer ◽

P Availability ◽

Agronomic Effectiveness ◽

Sewage Sludge Ash ◽

P Recovery ◽

Sludge Ash ◽

P Fertilizers

Abstract Phosphorus (P) recovery from incinerated sewage sludge ash (ISSA) has been extensively investigated, and various recovered phosphate fertilizers (RPFs) have been produced. In this study, three RPFs (calcium phosphate compounds (CaP), struvite (SP), and P-loaded biochar (BP)) produced from ISSA were characterized and their agronomic effectiveness were verified by pot experiments with the cultivation of choy sum (Brassica campestris L. ssp. Chinensis var. utillis Tsen et Lee) and ryegrass (Lolium perenne L.). The SP has the highest P purity while the BP has the most complex P species. And the plant growth results showed that the RPFs greatly facilitated plant growth and demonstrated superior/comparable effects to those of MP/CoF. In general, choy sum fertilized with SP showed the best effect due to the Mg involved and the high P purity of SP, while ryegrass fertilized with BP performed the best among all of the groups because of the additional nutritional elements and the high P availability of BP. Additionally, the accumulation of heavy metals in the plants under all conditions did not exceed the limits stipulated in the regulations. These results indicate that recovering P from ISSA is an attractive technology to produce P fertilizers, which can alleviate both the scarcity of phosphate resources and the burden of ISSA management.

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Potentials of using nanofiltration to recover phosphorus from sewage sludge

Water Science & Technology ◽

10.2166/wst.2008.119 ◽

2008 ◽

Vol 57 (5) ◽

pp. 707-714 ◽

Cited By ~ 14

Author(s):

C. Niewersch ◽

C. N. Koh ◽

T. Wintgens ◽

T. Melin ◽

C. Schaum ◽

...

Keyword(s):

Heavy Metals ◽

Sewage Sludge ◽

Product Recovery ◽

Phosphorus Recovery ◽

Nanofiltration Membranes ◽

Sewage Sludge Ash ◽

Model Solutions ◽

Treated Sewage ◽

Increasing Demand ◽

Sludge Ash

Due to the depletion of mineral phosphorus resources there is an increasing demand for efficient phosphorus recovery technologies. In this study the potential of nanofiltration to recover phosphorus from pre-treated sewage sludge is investigated. The efficiency of three commercial nanofiltration membranes (Desal 5DK, NP030; MPF34) was tested using model solutions. Desal 5DK showed the best selectivity for phosphorus. A pH of lower than 1.5 was found to be most suitable. Desal 5DK was used on four different sewage sludge ash eluates and on one sewage sludge. In these experiments it was shown that a separation of phosphorus from undesired components such as heavy metals was possible with significant variations in the efficiency for the different ash and sludge types. Additionally the achievable product recovery was investigated with model solutions. A product recovery of 57.1% was attained for pH 1 and 41.4% for pH 1.5.

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