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                                                                   EXHIBIT 10.22


                                ENVIROGEN, INC.

                        1990 INCENTIVE STOCK OPTION AND
                       NON-QUALIFIED STOCK OPTION PLAN*
                       -------------------------------   
              (As Amended and Restated Effective February 4, 1997)
                         
          1.  PURPOSE.  This Envirogen, Inc. 1990 Incentive Stock Option and
              -------                                                       
Non-Qualified Stock Option Plan ("Plan") is intended to provide a means whereby
Envirogen, Inc. (the "Company") may, through the grant of incentive stock
options ("ISOs") to purchase common stock of the Company ("Common Stock") to
officers and other key employees ("Key Employees") and through the grant of
nonqualified stock options ("NQSOs" and, collectively with ISOs, "Options") to
Key Employees, directors, scientific advisory board members and consultants
(together with Key Employees, "Optionees"), attract and retain such Key
Employees and other Optionees and motivate such Key Employees and other
Optionees to exercise their best efforts on behalf of the Company and of any
related corporation ("Related Corporation").

          For purposes of the Plan, a Related Corporation of the Company shall
mean either a corporate subsidiary of the Company, as defined in section 424(f)
of the Internal Revenue Code of 1986, as amended ("Code"), or the corporate
parent of the Company, as defined in section 424(e) of the Code.  Further, as
used in the Plan, (a) the term "incentive stock option" shall mean an option
which, at the time such option is granted under the Plan, qualifies as an ISO
within the meaning of section 422 of the Code and is designated as an ISO in the
Option Agreement (as hereinafter defined); and (b) the term "nonqualified stock
option" shall mean an option which, at the time such option is granted, does not
qualify as an ISO and/or is designated as an NQSO in the Option Agreement.

          2.  ADMINISTRATION.  The Plan shall be administered by the Company's
              --------------                                                  
Stock Option Committee ("Committee"), which shall consist of not less than three
(3) non-employee directors (within the meaning of Rule 16b-3(b)(3) under the
    ------------------------------------------------------------------------
Securities Exchange Act of 1934 (the "Exchange Act"), or any successor thereto)
-------------------------------------------------------------------------------
who are also outside directors (within the meaning of Treas. Reg. (S)1.162-
27(e)(3), or any successor thereto) of the Company who shall be appointed by,
and shall serve at the pleasure of, the Company's Board of Directors ("Board").
Each member of such Committee, while serving as such, shall be deemed to be
acting in his capacity as a director of the Company.

          The Committee shall have full authority, subject to the terms of the
Plan, to select the Key Employees and other Optionees to be granted ISOs and
NQSOs under the Plan, to grant options on behalf of the Company and to set the
date of grant and the other terms of such Options.  The Committee also shall
have the authority to establish such rules and regulations, not inconsistent
with the provisions of the Plan, for the proper administration of the Plan, and
to amend, modify or rescind any such rules and regulations, and to make such
determinations and interpretations under, or in connection with, the Plan, as it
deems necessary or advisable.  All such rules, regulations, determinations and
interpretations shall be binding and conclusive upon the Company, its
stockholders and all employees, and upon their

__________________________

*  The underscored language indicates amendments proposed to be adopted as
   described in Proposal 4.

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respective legal representatives, beneficiaries, successors and assigns and upon
all other persons claiming under or through any of them.

          3.   ELIGIBILITY.  The class of employees who shall be eligible to
               -----------                                                  
receive ISOs under the Plan and the class of persons who shall be eligible to
receive NQSOs under the Plan shall be, respectively, the Key Employees of the
Company and/or a Related Corporation and the other Optionees employed by or
otherwise associated with the Company and/or of a Related Corporation.  More
than one Option may be granted to an Optionee under the Plan.

          4.   STOCK.  Options may be granted under the Plan to purchase up to a
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maximum of three million five hundred thousand (3,500,000) shares of the
           -----------------------------------------------              
Company's Common Stock, par value $.01 per share, subject to adjustment as
hereinafter provided; provided, however that no Key Employee shall receive
Options for more than one million (1,000,000) shares of the Company's Common
                      -----------------------                               
Stock.  Shares issuable under the Plan may be authorized but unissued shares or
reacquired shares, and the Company may purchase shares required for this
purpose, from time to time, if it deems such purchase to be advisable.

          If any Option granted under the Plan expires or otherwise terminates
for any reason whatever (including, without limitation, the Optionee's surrender
thereof) without having been exercised, the shares subject to the unexercised
portion of such Option shall continue to be available for the granting of
Options under the Plan as fully as if such shares had never been subject to an
Option; provided, however, that (a) if an Option is cancelled, the cancelled
Option is counted against the maximum number of shares for which Options may be
granted to a Key Employee, and (b) if the Option price is reduced after the date
of grant, the transaction is treated as a cancellation of an Option and the
grant of a new Option for purposes of counting the maximum number of shares for
which Options may be granted to a Key Employee.

          5.   GRANTING OF OPTIONS.  From time to time until the expiration or
               -------------------                                            
earlier suspension or discontinuance of the Plan, the Committee may, on behalf
of the Company, grant to Optionees under the Plan such Options as it determines
are warranted; provided, however, that grants of ISOs and NQSOs shall be
separate and not in tandem.  The granting of an Option under the Plan shall not
be deemed either to entitle the Optionee to, or to disqualify the Optionee from,
any participation in any other grant of Options under the Plan.  In making any
determination as to whether an Optionee shall be granted an Option and as to the
number of shares to be covered by such Option, the Committee shall take into
account the duties of the Optionee, his present and potential contributions to
the success of the Company or a Related Corporation, and such other factors as
the Committee shall deem relevant in accomplishing the purposes of the Plan.
Moreover, the Committee may provide in the Option that said Option may be
exercised only if certain conditions, as determined by the Committee, are
fulfilled.

          6.   ANNUAL LIMIT.
               ------------ 

               a.  ISOs.
                   ---- 

          The aggregate fair market value (determined as of the time the ISO is
granted) of the Common Stock with respect to which ISOs are exercisable for the
first time by a Key Employee during any calendar year (under this Plan and any
other ISO plan of the Company or a Related Corporation) shall not exceed one
hundred thousand dollars ($100,000).

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               b.  NQSOs.
                   ----- 

               The annual limits set forth above for ISOs shall not apply to
NQSOs.

          7.   TERMS AND CONDITIONS OF OPTIONS.  The Options granted pursuant to
               -------------------------------                                  
the Plan shall expressly specify whether they are ISOs or NQSOs.  In addition,
the Options granted pursuant to the Plan shall include expressly or by reference
the following terms and conditions, as well as such other provisions not
inconsistent with the provisions of this Plan and, for ISOs granted under this
Plan, the provisions of section 422(b) of the Code, as the Committee shall deem
desirable:

               a.  Number of Shares.
                   ---------------- 

               A statement of the number of shares to which the Option pertains.

               b.  Price.
                   ----- 

               A statement of the Option price which shall be determined and
fixed by the Committee in its discretion but, in the case of an ISO, shall not
be less than the higher of one hundred percent (100%) (one hundred ten percent
(110%) in the case of more than ten percent (10%) stockholders as discussed in
(j) below) of the fair market value of the optioned shares of Common Stock, or
the par value thereof, on the date the ISO is granted and, in the case of an
NQSO, shall not be less than the higher of seventy-five percent (75%) of the
fair market value of the optioned shares of Common Stock, or the par value
thereof, on the date the NQSO is granted.

               The fair market value of the optioned shares of Common Stock
shall be arrived at by a good faith determination of the Committee and shall be
(i) the mean between the highest and lowest quoted selling price, if there is a
market for the Common Stock on a registered securities exchange or in an over
the counter market, on the date of grant, or (ii) the weighted average of the
means between the highest and lowest sales on the nearest date before and the
nearest date after the date of grant, if there are no sales on the date of grant
but there are sales on dates within a reasonable period both before and after
the date of grant, or (iii) the means between the bid and asked prices, as
reported by the National Quotation Bureau on the date of grant, if actual sales
are not available during a reasonable period beginning before and ending after
the date of grant, or (iv) such other method of determining fair market value as
shall be authorized by the Code, or the rules or regulations thereunder, and
adopted by the Committee. Where the fair market value of the optioned shares of
Common Stock is determined under (ii) above, the average of the means between
the highest and lowest sales on the nearest date before and the nearest date
after the date of grant is to be weighted inversely by the respective numbers of
trading days between the date of grant and such sales dates, in accordance with
Treas. Reg. (S) 20.2031-2(b)(1).

               c.  Term.
                   ---- 

               Subject to earlier termination as provided in Subsections (e),
(f), (g) and (j) below and in Section 9 hereof, the term of each Option shall be
not more than ten (10) years (five (5) years in the case of ISOs granted to more
than ten percent (10%) stockholders as discussed in (j) below) from the date of
grant.

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               d. Exercise.
                  -------- 

               Options shall be exercisable in such installments and on such
dates as the Committee may specify, provided that (i) unless approved by the
Stock Option Committee, in no event shall any Option become exercisable at a
rate in excess of 20% per annum from the date of grant (except that all
outstanding Options shall be immediately exercisable in the case of merger,
consolidation, or other business combination involving the sale or transfer of
all (or substantially all) of the assets of the Company, or other business
combination involving the sale or transfer of all (or substantially all) of the
capital stock of the Company in which the Company is not the surviving entity,
or, if it is the surviving entity, either (a) does not survive as an operating
ongoing concern in substantially the same line of business, or (b) is controlled
by persons or entities previously unaffiliated with the Company), (ii) in the
case of new Options granted to an Optionee in replacement for options (whether
granted under the Plan or otherwise) held by the Optionee, the new Options may
be made exercisable, if so determined by the Committee, in its discretion, at
the earliest date the replaced options were exercisable, but not earlier than
three (3) months from the date of grant of the new Options, and (iii) the
Committee may accelerate the exercise date of any outstanding Options, in its
discretion, if it deems such acceleration to be desirable. Any Option shares,
the right to the purchase of which has accrued, may be purchased at any time up
to the expiration or termination of the Option. Exercisable Options may be
exercised, in whole or in part, from time to time by giving written notice of
exercise to the Company at its principal office, specifying the number of shares
to be purchased and accompanied by payment in full of the aggregate Option price
for such shares. Only full shares shall be issued under the Plan, and any
fractional share which might otherwise be issuable upon exercise of an Option
granted hereunder shall be forfeited.

               The Option price shall be payable (i) in cash or its equivalent,
(ii) in the discretion of the Committee, in Company Common Stock previously
acquired by the Optionee, provided that if such shares of Common Stock were
acquired through exercise of an ISO and are used to pay the Option price of an
ISO, such shares have been held by the Key Employee for a period of not less
than the holding period described in section 422(a)(1) of the Code on the date
of exercise, or if such shares of Common Stock were acquired through exercise of
an NQSO or of an option under a similar plan, such shares have been held by the
Optionee for a period of more than one (1) year on the date of exercise, (iii)
in the discretion of the Committee, in any combination of (i) and (ii) above, or
(iv) in the discretion of the Committee, by delivering a properly executed
notice of exercise of the Option to the Company and a broker, with irrevocable
instructions to the broker promptly to deliver to the Company the amount of sale
or loan proceeds necessary to pay the exercise price of the Option, provided
that the payment procedure specified in this clause (iv) shall not be available
if such payment procedure would result in a violation of section 16(b) of the
Exchange Act.

               In the event such Option price is paid, in whole or in part, with
shares of Common Stock, the portion of the Option price so paid shall be equal
to the "fair market value" on the date of tender, as such "fair market value" is
determined in Subsection (b) above, of the Common Stock so tendered in payment
of such Option price.

               e.  Termination of Employment.
                   ------------------------- 

               If an Optionee's employment by the Company (and Related
Corporations) is terminated by either party prior to the expiration date fixed
for this Option for any reason other than death or disability, such Option may
be exercised, to the extent of the number of shares with respect to which the
Optionee could have exercised it on the date of such termination, by the
Optionee at any time prior to

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the earlier of (i) the expiration date specified in such option, or (ii) 30 days
after the date of the Optionee's termination of employment, or (iii) an
accelerated termination date of the option determined by the Committee, in its
discretion, except that such accelerated termination date shall not be earlier
than the date of the Optionee's termination of employment.

          For purposes of this Plan, in the case of an Optionee who is a
director or a scientific advisory board member of the Company or a Related
Corporation but who is not an employee of the Company or a Related Corporation,
such Optionee's "employment" with the Company and all related Corporations shall
be deemed to terminate when such Optionee ceases to be a director or a
scientific board member of the Company and all Related Corporations, and is no
longer providing ongoing consulting or advisory services to the Company and all
Related Corporations.  For purposes of this Plan, in the case of an Optionee who
is a consultant to the Company or a Related Corporation, such Optionee's
"employment" with the Company and all Related Corporations shall be deemed to
terminate when such Optionee is no longer providing ongoing consulting or
advisory services to the Company and all Related Corporations.

          f.  Exercise upon Disability of Optionee.
              ------------------------------------ 

          If an Optionee shall become disabled (within the meaning of section
22(e)(3) of the Code) during his employment and, prior to the expiration date
fixed for his Option, his employment is terminated as a consequence of such
disability, such Option may be exercised, to the extent of the number of shares
with respect to which the Optionee could have exercised it on the date of such
termination, or to any greater extent permitted by the Committee, by the
Optionee at any time prior to the earlier of (i) the expiration date specified
in such Option, or (ii) an accelerated termination date determined by the
Committee, in its discretion, except that such accelerated termination date
shall not be earlier than the date of the Optionee's termination of employment
by reason of disability, and in the case of ISOs, such date shall not be later
than one (1) year after such termination of employment.  In the event of the
Optionee's legal disability, such Option may be so exercised by the Optionee's
legal representative.

          g.  Exercise upon Death of Optionee.
              ------------------------------- 

          If an Optionee shall die during his employment and prior to the
expiration date fixed for his Option, or if an Optionee whose employment is
terminated by reason of Optionee's disability (as described in Subsection (f)
above) shall die following his termination of employment but prior to the
earliest of (i) the expiration date fixed for his Option, or (ii) the expiration
of the period determined under Subsection (f) above, or (iii) in the case of an
ISO, three (3) months following termination of employment, such Option may be
exercised, to the extent of the number of shares with respect to which the
Optionee could have exercised it on the date of his death, or to any greater
extent permitted by the Committee, by the Optionee's estate, personal
representative or beneficiary who acquired the right to exercise such option by
bequest or inheritance or by reason of the death of the Optionee, at any time
prior to the earlier of (i) the expiration date specified in such Option or (ii)
an accelerated termination date determined by the Committee, in its discretion,
except that such accelerated termination date shall not be later than one (1)
year after the date of death.

          h.  Non-Transferability.
              ------------------- 

          No Option shall be assignable or transferable by the Optionee
otherwise than by will or by the laws of descent and distribution, and during
the lifetime of the Optionee, the Option shall be

                                      F-5
<PAGE>
 
exercisable only by him or by his guardian or legal representative.  If the
Optionee is married at the time of exercise and if the Optionee so requests at
the time of exercise, the certificate or certificates shall be registered in the
name of the Optionee and the Optionee's spouse, jointly, with right of
survivorship.

          i.  Rights as a Stockholder.
              ----------------------- 

          An Optionee shall have no rights as a stockholder with respect to any
shares covered by his Option until the issuance of a stock certificate to him
for such shares.

          j.  Ten Percent Stockholder.
              ----------------------- 

          If the Key Employee owns more than ten percent (10%) of the total
combined voting power of all shares of stock of the Company or of a Related
Corporation at the time an ISO is granted to him, the Option price for the ISO
shall be not less than one hundred ten percent (110%) of the fair market value
of the optioned shares of Common Stock on the date the ISO is granted, and such
ISO, by its terms, shall not be exercisable after the expiration of five (5)
years from the date the ISO is granted.  The conditions set forth in this
Subsection (j) shall not apply to NQSOs.

          k.  Listing and Restriction of Shares.
              --------------------------------- 

          Each Option shall be subject to the requirement that, if at any time
the Committee shall determine, in its discretion, that the listing, registration
or qualifications of the shares covered thereby upon any securities exchange or
under any state or federal law, or the consent or approval of any governmental
regulatory body, is necessary or desirable as a condition of, or in connection
with, the granting of such Option or the purchase of shares thereunder, or that
action by the Company or by the Optionee should be taken in order to obtain an
exemption for any such requirement, no such Option may be exercised, in whole or
in part, unless and until such action shall have been effected, obtained, or
taken under conditions acceptable to the Committee.  Without limiting the
generality of the foregoing, each Optionee or his legal representative or
beneficiary may also be required to give satisfactory assurance that shares
purchased upon exercise of an Option are being purchased for investment and not
with a view to distribution, and certificates representing such shares may be
legended accordingly.

          l.  Withholding and Use of Shares to Satisfy Tax Obligations.
              -------------------------------------------------------- 

          The obligation of the Company to deliver shares of Common Stock upon
the exercise of any Option shall be subject to applicable federal, state and
local tax withholding requirements.

          If the exercise of any Option is subject to the withholding
requirements of applicable federal tax laws, the Committee, in its discretion
(and subject to such withholding rules ("Withholding Rules") as shall be adopted
by the Committee), may permit the Optionee to satisfy the federal withholding
tax, in whole or in part, by electing to have the Company withhold (or by
returning to the Company) shares of Common Stock, which shares shall be valued,
for this purpose, at their fair market value on the date the amount of tax
required to be withheld is determined (the "Determination Date").  Such election
must be made in compliance with and subject to the Withholding Rules, and the
Company may not withhold shares in excess of the number necessary to satisfy the
minimum federal income tax withholding requirements.  In the event shares of
Common Stock acquired under the exercise of an ISO are used to satisfy such
withholding requirement, such shares of Common Stock must have been held by the
Key Employee for a period of not less than the holding period described in
section 422(a)(1) of the

                                      F-6
<PAGE>
 
Code on the Determination Date.  In the event shares of Common Stock acquired
through exercise of an NQSO or of an option under a similar plan are used to
satisfy such withholding requirements, such shares must have been held by the
Optionee for a period of more than one (1) year on the Determination Date.

          8.  OPTION INSTRUMENTS - OTHER PROVISIONS.  Options granted under the
              -------------------------------------                            
Plan shall be evidenced by written documents ("Option Agreements") in such form
as the Committee shall, from time to time, approve, which Option Agreements
shall contain such provisions, not inconsistent with the provisions of the Plan
for NQSOs granted pursuant to the Plan, and such conditions, not inconsistent
with the provisions of the Plan and section 422(b) of the Code for ISOs granted
pursuant to the Plan, as the Committee shall deem advisable, and which Option
Agreements shall specify whether the Option is an ISO or NQSO.  Each Optionee
shall enter into, and be bound by, such Option Agreements, as soon as
practicable after the grant of an Option.

          9.  CAPITAL ADJUSTMENTS.  The number of shares which may be issued
              -------------------                                           
under the Plan, as stated in Section 4 hereof, and the maximum number of shares
with respect to which options may be granted to any Key Employee under the Plan
as stated in Section 4 hereof, and the number of shares issuable upon exercise
of outstanding Options under the Plan (as well as the Option price per share
under such outstanding Options), shall, subject to the provisions of section
424(a) of the Code, be proportionately adjusted, as may be deemed appropriate by
the Committee, to reflect any stock dividend, stock split, share combination, or
similar change in the capitalization of the Company.

          10.  AMENDMENT OR DISCONTINUANCE OF THE PLAN.
               --------------------------------------- 

          (a) GENERAL.  The Board from time to time may suspend or discontinue
              -------                                                         
the Plan or amend it in any respect whatsoever, except that the following
amendments shall require stockholder approval (given in the manner set forth in
Section 10(b) below):

               (i)  With respect to ISOs, any amendment which would: (A) change
          the class of employees eligible to participate in the Plan, (B) except
          as permitted under Section 9 hereof, increase the maximum number of
          shares of Common Stock with respect to which ISOs may be granted under
          the Plan, or (C) extend the duration of the Plan under Section 15
          hereof with respect to any ISOs granted hereunder; and

               (ii)  With respect to Options, any amendment which would require
          stockholder approval pursuant to Treas. Reg. (S) 1.162-27(e)(4)(vi) or
          any successor thereto.

Notwithstanding the foregoing, no such suspension, discontinuance or amendment
shall materially impair the rights of any holder of an outstanding Option
without the consent of such holder.

          (b)  STOCKHOLDER APPROVAL REQUIREMENTS.  The approval of stockholders
               ---------------------------------                               
must comply with all applicable provisions of the corporate charter, bylaws, and
applicable state law prescribing the method and degree of stockholder approval
required for the issuance of corporate stock or options.  If the applicable
state law does not prescribe a method and degree of stockholder approval in such
case, the approval of stockholders must be effected:

                    (i)  By a method and in a degree that would be treated as
               adequate under applicable state law in the case of an action
               requiring stockholder approval (i.e., an action
                                               ---            

                                      F-7
<PAGE>
 
               on which stockholders would be entitled to vote if the action
               were taken at a duly held stockholders' meeting); or

                    (ii)  By a majority of the votes cast at a duly held
               stockholders' meeting at which a quorum representing a majority
               of all outstanding voting stock is, either in person or by proxy,
               present and voting on the plan.

          11.  RIGHTS.  Neither the adoption of the Plan nor any action of the
               ------                                                         
Board or the Committee shall be deemed to give any individual any right to be
granted an Option, or any other right hereunder, unless and until the Committee
shall have granted such individual an Option, and then his rights shall be only
such as are provided by the Option Agreement.

          Any Option under the Plan shall not entitle the holder thereof to any
rights as a stockholder of the Company prior to the exercise of such Option and
the issuance of the shares pursuant thereto.  Further, notwithstanding any
provisions of the Plan or the Option Agreement with an Optionee, the Company
shall have the right, in its discretion, to retire an Optionee at any time in
accordance with its policies or otherwise to terminate his employment at any
time in accordance with its policies for any reason whatsoever.

          12.  APPLICATION OF FUNDS.  The proceeds received by the Company from
               --------------------                                            
the sale of Common Stock pursuant to Options granted under the Plan shall be
used for general corporate purposes.  Any cash received in payment for shares
upon exercise of an Option to purchase Common Stock shall be added to the
general funds of the Company and shall be used for its corporate purposes.  Any
Common Stock received in payment for shares upon exercise of an Option to
purchase Common Stock shall become treasury stock.

          13.  EFFECTIVE DATE.  This Plan shall become effective on April 20,
               --------------                                                
1990 (the date the Plan was adopted by the Board and by the stockholders).

          14.  NO OBLIGATION TO EXERCISE OPTION.  The granting of an Option
               --------------------------------                            
shall impose no obligation upon an Optionee to exercise such Option.

          15.  TERMINATION OF THE PLAN.  Unless earlier terminated as provided
               -----------------------                                        
in the Plan, the Plan and all authority granted hereunder shall terminate
absolutely at 12:00 midnight on March 31, 2000, which date is within ten (10)
years after the date the Plan was adopted by the Board, and no Options hereunder
shall be granted thereafter.  Nothing contained in this Section 15, however,
shall terminate or affect the continued existence of rights created under
Options issued hereunder and outstanding on March 31, 2000, which by their terms
extend beyond such date.

          16.  GOVERNING LAW.  With respect to any ISOs granted pursuant to the
               -------------                                                   
Plan and the Option Agreements thereunder, the Plan, such Option Agreements and
any ISOs granted pursuant thereto shall be governed by the applicable Code
provisions to the maximum extent possible.  Otherwise, the laws of the State of
Delaware shall govern the operation of, and the rights of Optionees under, the
Plan, the Option Agreements and any Options granted thereunder.

                                      F-8