SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13G

INFORMATION TO BE INCLUDED IN STATEMENTS FILED
PURSUANT TO RULES 13d-1(b), (c), AND (d) AND AMENDMENTS
THERETO FILED PURSUANT TO RULE 13d-2

Energy Recovery, Inc.

(Name of Issuer)

Common Shares

29270J 10 0

December 31, 2008

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

o RULE 13d-1(b)

o RULE 13d-1(c)

þ 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).

 

 

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ITEM 1(a)  NAME OF ISSUER:

 Energy Recovery, Inc.

ITEM 1(b)  ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICES:

 1908 Doolittle Drive, San Leandro, California 94577

ITEM 2(a)  NAME OF PERSON FILING:

 Arvarius AS; Marius Skaugen; Lafite AS; and Mouton AS.

ITEM 2(b)  ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE:

 Parkv.57 c/o B. Skaugen AS 0256, Oslo, Norway.

ITEM 2(c)  CITIZENSHIP:

 Norway

ITEM 2(d) TITLE OF CLASS OF SECURITIES:

 Common Shares

ITEM 2(e)  CUSIP NUMBER:

 29270J 10 0

ITEM 3      IF THIS STATEMENT IS FILED PURSUANT TO RULES 13d-1(b) OR 13d-2(b), CHECK WHETHER THE PERSON
                    FILING IS A:

                    Not applicable.

ITEM 4      OWNERSHIP:

 For Arvarius AS:

 (a) Amount beneficially owned: 10,026,533

 (b) Percent of class: 19.3%

 (c) Number of shares as to which such person has:

(i) sole power to vote or to direct the vote: -0-

(ii) shared power to vote or to direct the vote: 10,026,533

(iii) sole power to dispose or to direct the disposition: -0-

(iv) shared power to dispose or to direct the disposition: 10,026,533

 For Marius Skaugen:

 (a) Amount beneficially owned: 10,641,103

 (b) Percent of class: 20.5%

 (c) Number of shares as to which such person has:

(i) sole power to vote or to direct the vote: -0-

(ii) shared power to vote or to direct the vote: 10,641,103

(iii) sole power to dispose or to direct the disposition: -0-

(iv) shared power to dispose or to direct the disposition: 10,641,103

 For Lafite AS:

 (a) Amount beneficially owned: 307,285

 (b) Percent of class: 0.6%

 (c) Number of shares as to which such person has:

(i) sole power to vote or to direct the vote: -0-

(ii) shared power to vote or to direct the vote: 307,285

(iii) sole power to dispose or to direct the disposition: -0-

(iv) shared power to dispose or to direct the disposition: 307,285

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 For Mouton AS:

 (a) Amount beneficially owned: 307,285

 (b) Percent of class: 0.6%

 (c) Number of shares as to which such person has:

(i) sole power to vote or to direct the vote: -0-

(ii) shared power to vote or to direct the vote: 307,285

(iii) sole power to dispose or to direct the disposition: -0-

(iv) shared power to dispose or to direct the disposition: 307,285

Marius Skaugen is a controlling stockholder of Arvarius AS, Lafite AS, and Mouton AS. Shares reported above as beneficially owned by Arvarius SA and Marius Skaugen include shares that may be acquired upon exercise of warrants, issued to Arvarius AS, to purchase 1,904,122 common shares that are presently exercisable in full.

ITEM 5       OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

 Not applicable.

ITEM 6       OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

 Not applicable.

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

 Not applicable.

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.

		Date: February 2, 2009
		Arvarius SA
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, Director
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, individually
		Lafite SA
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, Director
		Mouton SA
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, Director

CUSIP NO. 29270J 10 0		13G		PAGE 8 OF 8 PAGES

JOINT FILING AGREEMENT

     We, the signatories of the statement on Schedule 13G to which this Agreement is attached, hereby agree that such statement is, and any amendments thereto filed by any of us will be, filed on behalf of each of us.

		Date: February 2, 2009
		Arvarius SA
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, Director
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, individually
		Lafite SA
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, Director
		Mouton SA
		Signature:		/s/ Marius Skaugen
		Name/Title: Marius Skaugen, Director