EP-4472932-B1 - INSTALLATION FOR MICROBIOLOGICAL WASTE WATER TREATMENT

EP4472932B1EP 4472932 B1EP4472932 B1EP 4472932B1EP-4472932-B1

Inventors

ZIJLSTRA, Hylcke
Prins, Rienk
MOZES, ERIK
HENDRICKX, TIM LUCAS GEORGE

Dates

Publication Date: 20260506
Application Date: 20221214

Claims (15)

A process of microbiologically treating an aqueous liquid comprising biodegradable substrate in an installation comprising (i) a bioreactor (1) containing a biomass sludge and (ii) a biomass separator (2) that is separated from the bioreactor and that comprises two or more inclined plate settlers (7) that are stacked on top of each other, said process comprising: • introducing the aqueous liquid comprising biodegradable substrate into the bioreactor; • transferring treated fluid that comprises biomass from the upper part of the bioreactor through an inlet (6) for a stream comprising treated liquid to the upper part of the biomass separator; • separating the treated fluid into a liquid phase having a reduced biomass content and a fluid phase enriched in biomass in the two or more inclined plate settlers, said two or more inclined plate settlers being located below the inlet for a stream comprising treated liquid; • removing liquid phase having a reduced biomass content from the two or more inclined plate settlers; and • transferring at least a part of the fluid phase enriched in biomass from the lower part of the biomass separator to the bioreactor; wherein the biomass separator has a footprint area A of 0.5 to 30 m 2 , said footprint area being equal to the horizontal surface area that is covered by the vertical projection of the biomass separator onto that horizontal surface area; and wherein the two or more inclined plate settlers comprise a total number of n inclined plate elements which together provide a total projected surface area (PSA) and a total projected surface area ratio (PSAR) that are calculated as follows: - PSA = ∑ i = 1 n psa i - PSAR = PSA / A psa i representing the aggregate projected surface area of inclined plate element i in m 2 , said aggregate projected surface area being equal to the horizontal component of the surface area of the inclined plate element; and wherein PSAR ≥ 2.8 + 0.17A; or • introducing a mixture of the aqueous liquid comprising biodegradable substrate and at least a part of a fluid phase enriched in biomass that is generated by the two or more inclined plate settlers into the bioreactor, wherein the mixture is produced (i) by introducing the aqueous liquid comprising biodegradable substrate into the lower part of the biomass separator and mixing said aqueous liquid with at least a part of the fluid phase enriched in biomass or (ii) by introducing both the aqueous liquid comprising biodegradable substrate and at least part of the fluid phase enriched in biomass into a mixing unit, mixing said aqueous liquid with at least a part of the fluid phase enriched in biomass and transferring the mixture of said aqueous liquid and the at least part of a fluid phase to the bioreactor; • transferring treated fluid that comprises biomass from the upper part of the bioreactor through an inlet for a stream comprising treated liquid (6) to the upper part of the biomass separator; • separating the treated fluid into a liquid phase having a reduced biomass content and a fluid phase enriched in biomass in the two or more inclined plate settlers, said two or more inclined plate settlers being located below the inlet for a stream comprising treated liquid; • removing liquid phase having a reduced biomass content from the two or more inclined plate settlers; wherein the biomass separator has a footprint area A of 0.5 to 30 m 2 , said footprint area being equal to the horizontal surface area that is covered by the vertical projection of the biomass separator onto that horizontal surface area; and wherein the two or more inclined plate settlers comprise a total number of n inclined plate elements which together provide a total projected surface area (PSA) and a total projected surface area ratio (PSAR) that are calculated as follows: - PSA = ∑ i = 1 n psa i - PSAR = PSA / A psa i representing the aggregate projected surface area of inclined plate element i in m 2 , said aggregate projected surface area being equal to the horizontal component of the surface area of the inclined plate element; and wherein PSAR ≥ 2.8 + 0.17A.
Process according to claim 1, wherein the biomass separator is operated to generate the liquid phase having a reduced biomass content at a flow velocity of at least 20 m 3 /hour/m 2 , the flow velocity being calculated by dividing the flow rate of the liquid phase having a reduced biomass content by the footprint area of the biomass separator.
Process according to claim 1 or 2, wherein the volume of the biomass separator is at least 5 times smaller than the volume of the bioreactor.
Process according to any one of the preceding claims, wherein the height of the fluid column in the bioreactor and the height of the fluid column in the biomass separator differ by not more than 5%.
Process according to any one of the preceding claims, wherein the biomass separator has a height : footprint area ratio of more than 1 m -1 .
Process according to any one of the preceding claims, wherein the inclined plate elements of the two or more inclined plate settlers consist of rectangular plates and wherein psa i is calculated as follows: psa i = I i x w i x cos Θ i wherein l i represents the length of inclined plate l in m; w i represents the width of inclined plate l in m; Θ i represents the pitch of inclined plate i.
Process according to any one of claims 1-5, wherein the inclined plate elements of the two or more inclined plate settlers consist of open-top cones that are stacked onto each other.
Process according to any one of claims 1-5, wherein the inclined plate elements in the two or more inclined plate settlers comprise: • at least two concentric enclosures including an outermost enclosure and an innermost enclosure and defining at least one concentric cavity; • one or more spiral-shaped channels formed in the at least one concentric cavity; • a fluid inlet for receiving fluid, located in the lower part of the one or more spiral-shaped channels; • a solids outlet, for discharging solids comprised in the fluid, located in a lower part of the separation device; and • a liquid outlet, for discharging liquid comprised in the fluid, located in the upper part of the one or more spiral shaped channels.
Process according to any one of the preceding claims, wherein the aqueous liquid comprising biodegradable substrate is introduced into the lower part of the bioreactor.
Process according to any one of claims 1-8, wherein the biomass separator comprises a conditioning chamber that is located underneath the two or more inclined plate settlers, wherein the aqueous liquid comprising biodegradable substrate is introduced into said conditioning chamber where it is mixed with the fluid phase enriched in biomass, following which the mixture of aqueous liquid and fluid phase is transferred to the lower part of the bioreactor.
Process according to any one of the preceding claims, wherein part of the fluid phase enriched in biomass that is obtained from the separation units is returned to the bioreactor and another part is discarded.
Process according to any one of the preceding claims, wherein both the bioreactor and the biomass separator comprise a headspace that is filled with biogas, wherein the headspace of the bioreactor and the headspace of the biomass separator are connected by a gas conduct, and wherein the process comprises removing biogas from the headspace of the bioreactor or from the headspace of the biomass separator.
Process according to any one of the preceding claims, wherein a tangential downward flow is realised in the upper part of the biomass separator.
Process according to any one of the preceding claims, wherein the bioreactor and the biomass separator are operated under anaerobic conditions.
An installation for microbiologically treating an aqueous liquid comprising a biodegradable substrate, wherein the installation comprises: • a bioreactor (1) comprising: - an inlet (4) for a stream comprising fluid phase enriched in biomass; and - an outlet (5) for treated liquid, located in the upper part of the bioreactor; • a biomass separator (2) that is separated from the bioreactor, comprising: - an inlet (6) for a stream comprising treated liquid located in the upper part of the biomass separator, said inlet for treated liquid being fluidly connected to outlet (5) of the bioreactor, - two or more inclined plate settlers (7) that are stacked on top of each other, located below inlet (6), each inclined plate settler having an outlet (8) for liquid phase having a reduced biomass content; - an outlet (9) for fluid enriched in biomass located in the lower part of the biomass separator underneath the two or more inclined plate settlers, said outlet (9) being fluidly connected to inlet (4) of the bioreactor; wherein the bioreactor comprises an inlet (3) for an aqueous liquid comprising a biodegradable substrate; and wherein the biomass separator has a footprint area A of 0.5 to 30 m 2 , said footprint area being equal to the horizontal surface area that is covered by the vertical projection of the biomass separator onto that horizontal surface area; and wherein the two or more inclined plate settlers comprise a total number of n inclined plate elements which together provide a total projected surface area (PSA) and a total projected surface area ratio (PSAR) that are calculated as follows: - PSA = ∑ i = 1 n psa i - PSAR = PSA / A psa i representing the aggregate projected surface area of inclined plate element i in m 2 , said aggregate projected surface area being equal to the horizontal component of the surface area of the inclined plate element; and wherein PSAR ≥ 2.8 + 0.17A; or • a bioreactor (1) comprising: - an inlet (4) for a stream comprising fluid phase enriched in biomass; and - an outlet (5) for treated liquid, located in the upper part of the bioreactor; • a biomass separator (2) that is separated from the bioreactor, comprising: - an inlet (6) for a stream comprising treated liquid located in the upper part of the biomass separator, said inlet for treated liquid being fluidly connected to outlet (5) of the bioreactor, - two or more inclined plate settlers (7) that are stacked on top of each other, located below inlet (6), each inclined plate settler having an outlet (8) for liquid phase having a reduced biomass content; - an outlet (9) for fluid enriched in biomass located in the lower part of the biomass separator underneath the two or more inclined plate settlers, said outlet (9) being fluidly connected to inlet (4) of the bioreactor; wherein the lower part of the biomass separator comprises an inlet (3) for an aqueous liquid comprising a biodegradable substrate; and wherein the biomass separator has a footprint area A of 0.5 to 30 m 2 , said footprint area being equal to the horizontal surface area that is covered by the vertical projection of the biomass separator onto that horizontal surface area; and wherein the two or more inclined plate settlers comprise a total number of n inclined plate elements which together provide a total projected surface area (PSA) and a total projected surface area ratio (PSAR) that are calculated as follows: - PSA = ∑ i = 1 n psa i - PSAR = PSA / A psa i representing the aggregate projected surface area of inclined plate element i in m 2 , said aggregate projected surface area being equal to the horizontal component of the surface area of the inclined plate element; and wherein PSAR ≥ 2.8 + 0.17A; or • a bioreactor (1) comprising: - an inlet (4) for a stream comprising fluid phase enriched in biomass; and - an outlet (5) for treated liquid, located in the upper part of the bioreactor; • a biomass separator (2) that is separated from the bioreactor, comprising: - an inlet (6) for a stream comprising treated liquid located in the upper part of the biomass separator, said inlet for treated liquid being fluidly connected to outlet (5) of the bioreactor, - two or more inclined plate settlers (7) that are stacked on top of each other, located below inlet (6), each inclined plate settler having an outlet (8) for liquid phase having a reduced biomass content; - an outlet (9) for fluid enriched in biomass located in the lower part of the biomass separator underneath the two or more inclined plate settlers, said outlet (9) being fluidly connected to inlet (20) of a mixing unit (19), which mixing unit comprises an outlet (21) that is fluidly connected to inlet (4) of the bioreactor; wherein the mixing unit comprises an inlet (3) for an aqueous liquid comprising a biodegradable substrate; and wherein the biomass separator has a footprint area A of 0.5 to 30 m 2 , said footprint area being equal to the horizontal surface area that is covered by the vertical projection of the biomass separator onto that horizontal surface area; and wherein the two or more inclined plate settlers comprise a total number of n inclined plate elements which together provide a total projected surface area (PSA) and a total projected surface area ratio (PSAR) that are calculated as follows: - PSA = ∑ i = 1 n psa i - PSAR = PSA / A psa i representing the aggregate projected surface area of inclined plate element i in m 2 , said aggregate projected surface area being equal to the horizontal component of the surface area of the inclined plate element; and wherein PSAR ≥ 2.8 + 0.17A.

Description

TECHNICAL FIELD OF THE INVENTION The invention relates to a process of microbiologically treating an aqueous liquid comprising biodegradable substrate in an installation comprising (i) a bioreactor containing a biomass sludge and (ii) a biomass separator that is separated from the bioreactor, said biomass separator comprising one or more inclined plate settlers, wherein the process comprises: transferring treated fluid that comprises biomass from the upper part of the bioreactor to the upper part of the biomass separator;separating the treated fluid into a liquid phase having a reduced biomass content and a fluid phase enriched in biomass in the one or more inclined plate settlers;removing liquid phase having a reduced biomass content from the one or more inclined plate settlers; andreturning at least a part of the fluid phase enriched in biomass from the lower part of the biomass separator to the bioreactor. The invention further relates to an installation that can be used for carrying out such a process. BACKGROUND OF THE INVENTION Anaerobic treatment of fluids / waste waters is typically done in a bioreactor, in which (granular) anaerobic biomass converts the organic pollutants into biogas, consisting mainly of methane and carbon dioxide. Typically, inside such bioreactors, devices are installed to separate the produced biogas from the treated fluid, and to separate the biomass from the degassed fluid. WO 2010/036107 describes a purifier for purification of waste water, comprising a reaction chamber (24) comprising a fermentation chamber (25) and, fitted above the fermentation chamber (25), a settling device (2) for a fluid containing liquid, gas and particulate material, said settling device comprising: a settling chamber (3) configured to be filled with the fluid;a liquid-discharge (5) for discharging liquid from the settling chamber, the liquid discharge (5) being arranged so as to be close to the liquid level (30) when in operation;a fluid inlet (6) configured to supply the fluid into the settling chamber (3) and arranged at essentially the same level as the liquid- discharge (5);a particulate material separation device (7); anda sludge outlet (8) from the settling chamber (3) wherein the inlet (6) comprises a gas separation device (4) for separating gas from the fluid, the gas separation device (4) comprising a row of oblique plates (13), the plates (13) being disposed in overlapping and parallel arrangement with their longitudinal axes at an angle to the horizontal such that fluid supplied through the inlet (6) is caused to flow obliquely downward along the oblique plates whilst gas bubbles (34) and/or light particles of the particulate material contained in the liquid are caused to be collected at an underside of one or more of the plates (13), to flow upward and to exit the gas separation device (4) at the inlet (6). WO 2007/078195 describes a process for the anaerobic purification of waste water using a sludge bed system, which process comprises feeding waste water and optionally recycle water, to the lower part of an upflow reactor, containing mainly granular biomass thus producing biogas in the treatment passing the resulting gas/liquid/solid mixture upward and separating the gas and solid from the liquid in a three phase separator and thereby generating an anaerobic effluent that is withdrawn from the top of the separator, the improvement comprising separating the solids from the liquid in a separator, wherein, above the separation of the gas from the liquid phase, tilted plates, tubes or other tilted internals are installed in the three phase separator body to increase the effective settling surface. WO 2012/005592 describes a purifier (100) for the purification of waste water, the purifier comprising: a reaction vessel (10) for a fluid, the reaction vessel having a reaction chamber (11) and a bottom (12);a downer (14) having a top end (91) and a bottom end (92), wherein the top end of the downer is connected to a fluid collector (13) to collect fluid from the reaction vessel (10), and the downer is arranged to transport the fluid towards the bottom (12) of the reaction vessel;a solids separation device (20) arranged to separate solids from liquid, the solids separation device comprising a fluid inlet (72) arranged to introduce fluid into the solids separation device and a liquid discharge (56) arranged to remove separated liquid from the solids separation device; characterized in, that the fluid inlet of the solids separation device (20) is connected to the bottom end (92) of the downer and the solids separation device is located inside the reaction vessel, on or near the bottom (12) of the reaction vessel. Recycling of microbiologically treated fluid with a high fluid flow rate over the separation device is beneficial for the hydraulic conditions in the bioreactor, as it can be used to create better mixing in the lower part of the bioreactor and a higher liquid up-flow velocity, thereby pr