Chemical phosphorus recovery from animal manure and digestate : Laboratory and pilot experiments

Abstract

Chemical phosphorus recovery from animal manure and digestate; Laboratory and pilot experiments.Wageningen, Wageningen Environmental Research, Report 2849. 114 pp.; 43 fig.; 37 tab.; 41 ref.Since a number of decades the Netherlands faces manure surpluses, because the amount of phosphate produced in animal manure is larger than the amount that can be applied on agricultural land according to the application limits. This surplus needs to be exported from the Dutch agricultural sector. The costs of manure export are however high, and therefore new, simple and cheap innovative techniques are needed to recover phosphate from fresh or digested manure (digestate). The relative small amount of concentrated recovered P can be transported more economically for use outside the Netherlands or can be utilized as secondary P resource for industries, e.g. for the production of fertiliser. We report laboratory and pilot experiments that were carried out in search for cheap and innovative techniques of phosphorus recovery. The main goal of the experiments was to reduce the P-content in pig slurry or digested pig slurry by 25% to 75%. If this goal can be reached with -recovery, in principle all manure including its valuable components (organic matter and other nutrients) can be applied sustainably on agricultural land in The Netherlands. The results show that both on laboratory scale and pilot scale 25-75% of P can be technically recovered with the so called 'acid-base approach'. From a sustainability point of view the impact is positives in terms of energy savings, CO 2 -savings, phosphorus savings and also nitrogen savings. The economical perspective is also positive but will strongly depend on the disposal prices of treated pig slurry with a reduced P content and its value as substitute for mineral N fertiliser and value in terms of organic soil improver on the manure market.Keywords: phosphate, manure, digestate, intensive livestock production, phosphate recovery, pig slurry, manure treatment, manure separation. • Acquisition, duplication and transmission of this publication is permitted with clear acknowledgement of the source.• Acquisition, duplication and transmission is not permitted for commercial purposes and/or monetary gain.• Acquisition, duplication and transmission is not permitted of any parts of this publication for which the copyrights clearly rest with other parties and/or are reserved. New innovative approaches are needed to close the phosphorus (P) cycle in The Netherlands because the agricultural sector currently produces about 25% more P, in the form of manure, than can be applied on land. One promising solution to deal with the surplus amount of P in manure is to recover the surplus of P in the form of a mineral P product for use as a P fertiliser (for export) or as a raw P feedstock for the P fertiliser industries. This idea for 'closing the manure P cycle in The Netherlands' has been circulating for a while, but was never thought well over until in 2013 a Public Private Partnership (PPP) was set up with t...

Does acidification increase the nitrogen fertilizer replacement value of bio‐based fertilizers?

“…To reduce the initial pH (≈ 8) of products to the pH level of 5.5, 18 g of H 2 SO 4 (18 M) per L product was required for PS and its LF, while 27 g of H 2 SO 4 (18 M) per L product was added for acidification of DIG and LF of digestate. These quantities are in agreement with the ones reported by Schoumans et al (), but higher than the ones observed by Kai et al () and Sørensen and Eriksen (). The required amount of acid can differ for different types of manure, because animal type, feed type and duration of storage influence the composition and hence the buffer capacity of manure ( Schoumans et al, ).…”

Fosfaatvormen in melkveemest en potentieel voor terugwinning

“…Initiele pH pH=6 pH=5 (Schoumans et al, 2017) en daarmee in lijn is met deze studie. Voor zuiveringsslib zijn meer gegevens beschikbaar en worden orthofosfaat gehalten ten hoogte van 20-40% van totaal fosfaat gemeten (Marti et al, 2008;Regelink et al, 2017) wat verklaard kan worden door de lagere calcium gehalten waardoor minder fosfaat kan precipiteren.…”

“…Schoumans et al (2017) onderzocht de perspectieven voor terugwinning van fosfaat uit de dunne fractie van varkensmest door dosering van magnesium. In deze studie werd geconcludeerd dat er onvoldoende struviet vorming optreedt en terugwinning uit de dunne fractie daarom geen perspectief biedt.…”

“…Omdat het fosfaatgehalte in dikke fractie van rundermest relatief laag is in vergelijking met de dikke fractie van varkensmest zullen de kosten voor behandeling van rundermest per kg fosfaat hoger zijn dan bij behandeling van varkensmest. Dit blijkt wanneer de zuurdosering wordt uitgedrukt per mol winbaar fosfaat (8 -26 mol/mol) en vergeleken wordt met de zuurdosering bij behandeling van dikke fractie van varkensmest (6 mol/mol) (Schoumans et al, 2017). Voor vergiste varkensmest kan fosfaatterugwinning uit de dikke fractie digestaat naar verwachting economisch concurreren met de rechtstreekse afzet van varkensmest (Schoumans et al, 2017).…”

“…Dit blijkt wanneer de zuurdosering wordt uitgedrukt per mol winbaar fosfaat (8 -26 mol/mol) en vergeleken wordt met de zuurdosering bij behandeling van dikke fractie van varkensmest (6 mol/mol) (Schoumans et al, 2017). Voor vergiste varkensmest kan fosfaatterugwinning uit de dikke fractie digestaat naar verwachting economisch concurreren met de rechtstreekse afzet van varkensmest (Schoumans et al, 2017). Het is echter waarschijnlijk dat behandeling van de dikke fractie voor rundermest geen economische voordelen biedt omdat de afzetkosten voor rundermest lager zijn dan voor varkensmest.…”