Prosecution Insights
Last updated: April 19, 2026
Application No. 18/542,721

METHODS OF LOW TRANS-MEMBRANE PRESSURE OR VACUUM FILTRATION

Non-Final OA §102
Filed
Dec 17, 2023
Examiner
SPIES, BRADLEY R
Art Unit
1777
Tech Center
1700 — Chemical & Materials Engineering
Assignee
643096 Alberta Limited
OA Round
1 (Non-Final)
74%
Grant Probability
Favorable
1-2
OA Rounds
2y 6m
To Grant
95%
With Interview

Examiner Intelligence

Grants 74% — above average
74%
Career Allow Rate
596 granted / 807 resolved
+8.9% vs TC avg
Strong +21% interview lift
Without
With
+20.9%
Interview Lift
resolved cases with interview
Typical timeline
2y 6m
Avg Prosecution
35 currently pending
Career history
842
Total Applications
across all art units

Statute-Specific Performance

§101
0.6%
-39.4% vs TC avg
§103
45.0%
+5.0% vs TC avg
§102
21.3%
-18.7% vs TC avg
§112
19.0%
-21.0% vs TC avg
Black line = Tech Center average estimate • Based on career data from 807 resolved cases

Office Action

§102
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA. Claim Interpretation The instant claim language uses relative terms e.g. “low” and “near-zero” to describe transmembrane pressure limitations. However, such limitations are properly definite because the instant specification provides sufficient guidance for one of ordinary skill in the art to ascertain the requisite degree and be reasonable apprised of the scope of the invention; specifically, the specification establishes that a low trans-membrane pressure represents a value of less than 25 kPa or similar [0013]. Claim Rejections - 35 USC § 102 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis ( i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale , or otherwise available to the public before the effective filing date of the claimed invention. Claims 11 , 12, 14-16, 18, and 20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Kang et al (KR 10-1745146 B1). With respect to claim s 11 and 20 , Kang teaches methods of membrane filtration to reduce or mitigate fouling in which iron oxide powder is added and coated onto the surface of the membrane thereby delaying fouling of the membrane by colloidal material [Translation pg. 9, paragraphs 3-6]. The process involves operating at a low transmembrane pressure i.e. a value below 0.25 bar/25 kPA for extended periods of time [Figs. 6-7]. Kang does not explicitly teach the presence of a colloid-free gap during the operations, however such a gap would necessarily be present at least initially and, absent clarification of the required conditions, is considered an inherent feature of the operations at low transmembrane pressure at least for an initial period of time. The membrane is present in a suitable tank (20) i.e. for pretreatment. Given the broadest reasonable interpretation, Kang’s process therefore anticipates the claimed invention of claims 11 and 20. With respect to claim 12 , as above Kang teaches loading the oxide powder into the system and depositing onto the membrane surface while performing filtration. With respect to claim 14 , Kang teaches experiments based on a constant flow rate which would suggest a constant loading rate [translation pg. 10, final paragraph]. With respect to claims 15, 16, and 18 , Kang examines behavior for backwashing, and teaches that increases in trans-membrane pressure during filtration indicate fouling (i.e. breakdown of the colloid-free gap) and that this can be mitigated by backwashing [translation pg. 11, 4 th paragraph]. Allowable Subject Matter Claims 1-10 are allowed. Similarly, claims 13, 17, and 19 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. The following is an examiner’s statement of reasons for allowance: The closest prior art regarding the use of membranes at low transmembrane pressure, treated with oxide powder, is taught by Kang et al (KR 10-1745146 B1 – see translated copy provided by applicant on an IDS). Kang teaches membrane operations using modified membranes at very low transmembrane pressures for extended periods of time generally consistent with the invention e.g. below 25 kPa/0.25 bar for tens of hours [Figs. 6-7]; the operations include addition of iron oxide powder in a manner which allows it to coat onto the surface of the membrane and thereby reduce fouling by contaminants [translation pg. 9, 3 rd paragraph and final paragraph ] . As discussed above, it may be considered that there is inherently at least some period in which a colloid-free gap is maintained due to the extremely low transmembrane pressure; however, there is no teaching or suggestion by Kang that such a gap, whether or not its present, is an object of the invention to be maintained and, specifically, controlled around by controlling filtration loading; at most Kang suggests backwashing based on indications of gap breakdown via increases in trans-membrane pressure . There is no teaching or suggestion by Kang of adjusting a filtration loading rate in order to maintain a colloid-free gap for such a membrane. Further, while adjustment of filtration loading rates and the like for mitigating fouling are well known in the art e.g. as taught by Beck et al (WO 9628236 A1) which teaches various methods for monitoring and characterizing fouling conditions, and adjusting membrane operations to optimize performance in view of this [Abs]. However, there is no teaching or suggestion of optimizing specifically around creation or maintenance of a colloid-free gap between the membrane surface (or a powder deposited thereon) and the bulk of the feed. As such, the prior art alone or in combination would not have led one of ordinary skill in the art to arrive at the claimed invention i.e. a method which requires controlling filtration loading specifically to maintain a colloid-free gap. The invention of claims 1-10 is therefore free from the prior art and allowed. Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee. Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.” Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to FILLIN "Examiner name" \* MERGEFORMAT BRADLEY R SPIES whose telephone number is FILLIN "Phone number" \* MERGEFORMAT (571)272-3469 . The examiner can normally be reached FILLIN "Work Schedule?" \* MERGEFORMAT Mon-Thurs 8AM-4PM . Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, FILLIN "SPE Name?" \* MERGEFORMAT Jennifer Dieterle can be reached at FILLIN "SPE Phone?" \* MERGEFORMAT (571)270-7872 . The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /BRADLEY R SPIES/ Primary Examiner, Art Unit 1777
Read full office action

Prosecution Timeline

Dec 17, 2023
Application Filed
Feb 25, 2026
Non-Final Rejection — §102 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
74%
Grant Probability
95%
With Interview (+20.9%)
2y 6m
Median Time to Grant
Low
PTA Risk
Based on 807 resolved cases by this examiner. Grant probability derived from career allow rate.

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