<PAGE>
 
As filed with the Securities and Exchange Commission on July 18, 1997

                                      Registration Statement No. 333-___________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                 F 0 R M  S-8

                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

                                ENVIROGEN, INC.
                -----------------------------------------------
            (Exact name of registrant as specified in its charter)

                    Delaware                        22-2899415
         ---------------------------------     ---------------------
          (State or other jurisdiction of        (I.R.S. Employer
           incorporation or organization)        Identification No.)

                            4100 Quakerbridge Road
                       Lawrenceville, New Jersey  08648
          -----------------------------------------------------------
             (Address of principal executive offices)  (Zip Code)

                                Envirogen, Inc.
        1990 Incentive Stock Option And Non-Qualified Stock Option Plan
        ---------------------------------------------------------------
                           (Full title of the plan)

                         Harcharan S. Gill, President
                                Envirogen, Inc.
                            4100 Quakerbridge Road
                       Lawrenceville, New Jersey  08648
                  -------------------------------------------
                    (Name and address of agent for service)

Telephone number, including area code, of agent for service: (609) 936-9300
                                                             --------------

                                   Copy to:

                          John E. Stoddard III, Esq.
                          Drinker Biddle & Reath LLP
                             105 College Road East
                       Princeton, New Jersey  08542-0627

<TABLE>
<CAPTION>
 
-----------------------------------------------------------------------------------------------
                                CALCULATION OF REGISTRATION FEE
----------------------------------------------------------------------------------------------- 
  Title of                     Amount of     Proposed maximum        Proposed         Amount of  
securities to                shares to be     offering price     maximum aggregate   registration
be registered                registered(1)     per share (2)     offering price (2)      fee
----------------------------------------------------------------------------------------------- 
<S>                          <C>             <C>                 <C>                 <C>
Common Stock,                     276,720      $  2.95             $  816,324
par value $.01
per share
 
                                1,223,280      $2.6875             $3,287,565
 
TOTAL                           1,500,000                          $4,103,889          $1,244
----------------------------------------------------------------------------------------------- 
</TABLE>
<PAGE>
 
----------------

(1)  Pursuant to Rule 416(a), this Registration Statement also registers such
     indeterminate number of additional shares as may become issuable under the
     Plan in connection with share splits, share dividends or similar
     transactions.

(2)  Calculated pursuant to Rule 457(h).  As to shares subject to outstanding
     but unexercised options, the price and fee are computed based upon the
     price at which such options may be exercised.  As to the remaining shares,
     the price and fee are computed based upon $2.6875, the average of the high
     and low prices for the common stock as reported on the NASDAQ SmallCap
     Market on July 14, 1997.

                                      -2-
<PAGE>
 
                                    PART II
              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


          Pursuant to General Instruction E (Registration of Additional
     Securities) to Form S-8, the Registrant hereby incorporates by reference
     the contents of its Registration Statement on Form S-8 (Registration No.
     33-54708) and of its Registration Statement on Form S-8 (Registration No.
     333-09267), both relating to the Envirogen, Inc. 1990 Incentive Stock
     Option and Non-Qualified Stock Option Plan, except for the Items set forth
     below.


Item 5.    Interests of Named Experts and Counsel.
           -------------------------------------- 

     Morgan R. Jones, the Secretary of the Company, is a partner in Drinker
     Biddle & Reath LLP.  Drinker Biddle & Reath LLP is counsel to the Company
     and assisted the Company in the preparation of this Registration Statement.


Item 8.   Exhibits.
          -------- 


Exhibit 4      Envirogen, Inc. 1990 Incentive Stock Option and Non-Qualified
               Stock Option Plan (as amended and restated effective 
               February 4, 1997)

Exhibit 5      Opinion of Drinker Biddle & Reath LLP, counsel to the Registrant

Exhibit 23(a)  Consent of Coopers & Lybrand L.L.P. (Independent Accountants)

Exhibit 23(b)  Consent of Drinker Biddle & Reath LLP (included in the opinion
               filed as Exhibit 5 hereto)

Exhibit 24     Powers of Attorney

                                      -3-
<PAGE>
 
                                  SIGNATURES

          Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Lawrenceville, State of New Jersey, on this 18th day
of July, 1997.

                              ENVIROGEN, INC.


                              By:/s/ Harcharan S. Gill
                                 -----------------------------
                                 Harcharan S. Gill
                                 President

                                      -4-
<PAGE>
 
          Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons, in the
capacities and on the date indicated.

<TABLE>
<CAPTION>
 
Signature                            Title                Date
---------                            -----                ----
<S>                         <C>                       <C>
 
/s/  Harcharan S. Gill      Director, President and   July 18, 1997
--------------------------  Chief Executive Officer
Harcharan S. Gill           (Principal Executive
                            Officer)
 
 
William C. Smith *          Director, Chairman of     July 18, 1997
--------------------------  the Board and Acting
William C. Smith            Chief Financial Officer
                            (Principal Financial
                            Officer)
 
/s/ Patricia A. McQueary    Controller (Principal     July 18, 1997
--------------------------  Accounting Officer)
Patricia A. McQueary
 
Robert F. Hendrickson *     Director                  July 18, 1997
--------------------------
Robert F. Hendrickson
 
Robert S. Hilles *          Director                  July 18, 1997
--------------------------
Robert S. Hillas
 
Robert F. Johnston *        Director                  July 18, 1997
--------------------------
Robert F. Johnston
 
Robert C. Miller *          Director                  July 18, 1997
--------------------------
Robert C. Miller

Peter J. Neff *             Director                  July 18, 1997
--------------------------
Peter J. Neff
</TABLE>

*    Harcharan S. Gill, pursuant to a Power of Attorney executed by each of the
     directors and officers noted above and included as Exhibit 24 of this
     Registration Statement, by signing his name hereto, does hereby sign and
     execute this Registration Statement on behalf of each of the persons noted
     above, in the capacities indicated, and does hereby sign and execute this
     Registration Statement on his own behalf, in the capacities indicated.

/s/  Harcharan S. Gill
-------------------------
     Harcharan S. Gill

                                      -5-
<PAGE>
 
                                 EXHIBIT INDEX



Exhibit   Description
Number    of Exhibit
------    ----------

4         Envirogen, Inc. 1990 Incentive Stock Option and
          Non-Qualified Stock Option Plan (as amended and
          restated effective February 4, 1997)

5         Opinion of Drinker Biddle & Reath LLP

23(a)     Consent of Coopers & Lybrand L.L.P.

23(b)     Consent of Drinker Biddle & Reath LLP
          (included in the opinion filed
          as Exhibit 5 hereto)

24        Powers of Attorney

                                      -6-
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 9130}]
{"company-data": {"conformed-name": "ENVIROGEN INC", "cik": "0000863815", "assigned-sic": "4955", "irs-number": "222899415", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-31567", "film-number": "97642504"}, "business-address": {"street1": "4100 QUAKERBRIDGE RD", "street2": "PRINCETON RESEARCH CENTER", "city": "LAWRENCEVILLE", "state": "NJ", "zip": "08648", "phone": "6099369300"}, "mail-address": {"street1": "PRINCETON RESEARCH CENTER", "street2": "4100 QUAKERBRIDGE RD", "city": "LAWRENCEVILLE", "state": "NJ", "zip": "08648"}}
As filed with the Securities and Exchange Commission on July 18, 1997

                                      Registration Statement No. 333-___________
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                 F 0 R M  S-8

                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

                                ENVIROGEN, INC.
                -----------------------------------------------
            (Exact name of registrant as specified in its charter)

                    Delaware                        22-2899415
         ---------------------------------     ---------------------
          (State or other jurisdiction of        (I.R.S. Employer
           incorporation or organization)        Identification No.)

                            4100 Quakerbridge Road
                       Lawrenceville, New Jersey  08648
          -----------------------------------------------------------
             (Address of principal executive offices)  (Zip Code)

                                Envirogen, Inc.
        1990 Incentive Stock Option And Non-Qualified Stock Option Plan
        ---------------------------------------------------------------
                           (Full title of the plan)

                         Harcharan S. Gill, President
                                Envirogen, Inc.
                            4100 Quakerbridge Road
                       Lawrenceville, New Jersey  08648
                  -------------------------------------------
                    (Name and address of agent for service)

Telephone number, including area code, of agent for service: (609) 936-9300
                                                             --------------

                                   Copy to:

                          John E. Stoddard III, Esq.
                          Drinker Biddle & Reath LLP
                             105 College Road East
                       Princeton, New Jersey  08542-0627
-----------------------------------------------------------------------------------------------
                                CALCULATION OF REGISTRATION FEE
----------------------------------------------------------------------------------------------- 
  Title of                     Amount of     Proposed maximum        Proposed         Amount of  
securities to                shares to be     offering price     maximum aggregate   registration
be registered                registered(1)     per share (2)     offering price (2)      fee
-----------------------------------------------------------------------------------------------
Common Stock,                     276,720      $  2.95             $  816,324
par value $.01
per share
 
                                1,223,280      $2.6875             $3,287,565
 
TOTAL                           1,500,000                          $4,103,889          $1,244
-----------------------------------------------------------------------------------------------
----------------

(1)  Pursuant to Rule 416(a), this Registration Statement also registers such
     indeterminate number of additional shares as may become issuable under the
     Plan in connection with share splits, share dividends or similar
     transactions.

(2)  Calculated pursuant to Rule 457(h).  As to shares subject to outstanding
     but unexercised options, the price and fee are computed based upon the
     price at which such options may be exercised.  As to the remaining shares,
     the price and fee are computed based upon $2.6875, the average of the high
     and low prices for the common stock as reported on the NASDAQ SmallCap
     Market on July 14, 1997.

                                      -2-
PART II
              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

          Pursuant to General Instruction E (Registration of Additional
     Securities) to Form S-8, the Registrant hereby incorporates by reference
     the contents of its Registration Statement on Form S-8 (Registration No.
     33-54708) and of its Registration Statement on Form S-8 (Registration No.
     333-09267), both relating to the Envirogen, Inc. 1990 Incentive Stock
     Option and Non-Qualified Stock Option Plan, except for the Items set forth
     below.

Item 5.    Interests of Named Experts and Counsel.
           -------------------------------------- 

     Morgan R. Jones, the Secretary of the Company, is a partner in Drinker
     Biddle & Reath LLP.  Drinker Biddle & Reath LLP is counsel to the Company
     and assisted the Company in the preparation of this Registration Statement.

Item 8.   Exhibits.
          -------- 

Exhibit 4      Envirogen, Inc. 1990 Incentive Stock Option and Non-Qualified
               Stock Option Plan (as amended and restated effective 
               February 4, 1997)

Exhibit 5      Opinion of Drinker Biddle & Reath LLP, counsel to the Registrant

Exhibit 23(a)  Consent of Coopers & Lybrand L.L.P. (Independent Accountants)

Exhibit 23(b)  Consent of Drinker Biddle & Reath LLP (included in the opinion
               filed as Exhibit 5 hereto)

Exhibit 24     Powers of Attorney

                                      -3-
SIGNATURES

          Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Lawrenceville, State of New Jersey, on this 18th day
of July, 1997.

                              ENVIROGEN, INC.

                              By:/s/ Harcharan S. Gill
                                 -----------------------------
                                 Harcharan S. Gill
                                 President

                                      -4-
Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons, in the
capacities and on the date indicated.
Signature                            Title                Date
---------                            -----                ----
/s/  Harcharan S. Gill      Director, President and   July 18, 1997
--------------------------  Chief Executive Officer
Harcharan S. Gill           (Principal Executive
                            Officer)
 
 
William C. Smith *          Director, Chairman of     July 18, 1997
--------------------------  the Board and Acting
William C. Smith            Chief Financial Officer
                            (Principal Financial
                            Officer)
 
/s/ Patricia A. McQueary    Controller (Principal     July 18, 1997
--------------------------  Accounting Officer)
Patricia A. McQueary
 
Robert F. Hendrickson *     Director                  July 18, 1997
--------------------------
Robert F. Hendrickson
 
Robert S. Hilles *          Director                  July 18, 1997
--------------------------
Robert S. Hillas
 
Robert F. Johnston *        Director                  July 18, 1997
--------------------------
Robert F. Johnston
 
Robert C. Miller *          Director                  July 18, 1997
--------------------------
Robert C. Miller

Peter J. Neff *             Director                  July 18, 1997
--------------------------
Peter J. Neff
*    Harcharan S. Gill, pursuant to a Power of Attorney executed by each of the
     directors and officers noted above and included as Exhibit 24 of this
     Registration Statement, by signing his name hereto, does hereby sign and
     execute this Registration Statement on behalf of each of the persons noted
     above, in the capacities indicated, and does hereby sign and execute this
     Registration Statement on his own behalf, in the capacities indicated.

/s/  Harcharan S. Gill
-------------------------
     Harcharan S. Gill

                                      -5-
EXHIBIT INDEX

Exhibit   Description
Number    of Exhibit
------    ----------

4         Envirogen, Inc. 1990 Incentive Stock Option and
          Non-Qualified Stock Option Plan (as amended and
          restated effective February 4, 1997)

5         Opinion of Drinker Biddle & Reath LLP

23(a)     Consent of Coopers & Lybrand L.L.P.

23(b)     Consent of Drinker Biddle & Reath LLP
          (included in the opinion filed
          as Exhibit 5 hereto)

24        Powers of Attorney

                                      -6-