UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. 3)*

Energy Recovery, Inc.

(Name of Issuer)

Common Stock, $0.001 par value

(Title of Class of Securities)

29270J100

(CUSIP Number)

October 18, 2021

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

[ ] Rule 13d-1(b)

[X] Rule 13d-1(c)

[ ] Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

CUSIP No. 29270J100

Names of Reporting Persons.

Arvarius AS

Check the Appropriate Box if a Member of a Group (See Instructions)

(a) ______

(b) ______

3. SEC Use Only

Citizenship or Place of Organization Norway

Number of

Beneficially

Owned by

Each Reporting

Person With:

5. Sole Voting Power -0-

6. Shared Voting Power -0-

7. Sole Dispositive Power -0-

8. Shared Dispositive Power -0-

Aggregate Amount Beneficially Owned by Each Reporting Person -0-

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
Instructions) ______

11.

Percent of Class Represented by Amount in Row (9) 0%

12.

Type of Reporting Person (See Instructions) CO

CUSIP No. 29270J100

Item 1.

(a)

Name of Issuer

Energy Recovery, Inc.

(b)

Address of Issuer's Principal Executive Offices

1717 Doolittle Drive, San Leandro, CA 94577

Item 2.

(a)

The name of the person filing this statement is:

Arvarius AS

The original Schedule 13G for the Stock and the amendments prior to this Amendment No. 3 also include as a joint filer Marius Skaugen, who was an indirect beneficial owner of shares held by Arvarius AS. On October 18, 2021, Arvarius AS ceased to hold any Stock of the Issuer, but Mr. Skaugen continued to indirectly beneficially own Stock of the Issuer through another entity, Haut Brion AS. As a result, Arvarius AS is filing this Schedule 13G to report that it is no longer a beneficial owner of the Issuer’s Stock, and Mr. Skaugen and Haut Brion AS will separately file a Schedule 13G to report their beneficial ownership of the Issuer’s Stock.

(b)

The principal business office of the Filers is located at:

Parkveien 57
c/o B. Skaugen
Oslo Q8 AS 0256

(c)

For citizenship of Filers, see Item 4 of the cover sheet for each Filer.

(d)

This statement relates to shares of Common Stock, $0.001 par value of the Issuer (the "Stock").

(e)

The CUSIP number of the Issuer is: 29270J100

CUSIP No. 29270J100

Item 3.

If this statement is filed pursuant to rule 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

[ ] Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b)

[ ] Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c)

[ ] Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d)

[ ] Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8).

(e)

[ ] An investment adviser in accordance with section 240.13d-1(b)(1)(ii)(E).

(f)

[ ] An employee benefit plan or endowment fund in accordance with section 240.13d-1(b)(1)(ii)(F).

(g)

[ ] A parent holding company or control person in accordance with 240.13d-1(b)(1)(ii)(G)

(h)

[ ] A savings association as defined in section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813).

(i)

[ ] A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3).

(j)

[ ] A non-U.S. institution in accordance with §240.13d-1(b)(ii)(J).

(k)

[ ] Group, in accordance with Rule 13d-1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with §240.13d-1(b)(1)(ii)(J), please specify the type of institution _______________________________________________________________.

Item 4.

Ownership.

See Items 5-9 and 11 of the cover page.

Item 5.

Ownership of Five Percent or Less of a Class

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [ X ].

Item 6.

Ownership of More than Five Percent on Behalf of Another Person.

Not applicable.

CUSIP No. 29270J100

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company.

Not applicable.

Item 8.

Identification and Classification of Members of the Group.

Not applicable

Item 9.

Notice of Dissolution of Group

Not applicable.

Item 10.

Certification.

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: October 28, 2021

ARVARIUS AS

By: /s/ Marius Skaugen, Director