The Alexandria City Council voted last night to raise council members' salaries by a third, from $7,500 to $10,000 a year. The mayor's salary will be raised by 22 percent, from $8,200 to $10,000.

The raises won't go into effect until a new council takes office following the May 1 election.

"Salaries we are paid are a mere pittance," complained council member Ellen Pickering (I), who wanted salaries raised to $15,000 a year.

"Whatever happened to fiscal restraint?" rejoined council member Robert L. Calhoun (D). who then joined four of his colleagues to defeat Pickering's proposal.

The motion to raise salaries to $10,000 a year was made by council member Beverly Beidler, a Democrat who is retiring from the council this year.

Voting with her were Donald C. Casey, Nicholas A. Colasanto and Nora Lamborne, all Democrats. Voting against the motion were Mayor Frank E. Mann (I), Calhoun and Pickering.

The Alexandria council is the second Washington area governing body to vote raises this week. On Monday, the Fairfax County Board of Supervisors, citing long hours and poor pay, voted to hold a public hearing on a proposal to raise their own pay from $15,000 to $22,000 a year and that of their chairman from $15,000 to $25,000.

In other action last night, the Alexandria council voted unanimously to accept the donation by Colssanto of two dilapidated houses he owns in the Del Ray section of the city. Citizen protests over Colasanto's longstanding refusal to upgrade the property, which had been condemned as unfit for human habitation, was cited by political observers as a reason for Colassanto's defeat in the Democratic primary March 6.

Colassanto offered the property to the city on the condition it be used to benefit elderly citizens. Last night, Mann called the offer "very generous."

Beidler introduced a measure that would ban so-called instant bingo from the city's bingo parlors. A public hearing was scheduled for April 12. The option of banning this form of bingo was made availble under Virginia's new bingo law.

It is estimated that at least a third of the $1.2 million annual gross realized by bingo operators in the state comes from instant bingo, a variation of the game in which players imply uncover a window of a card to see if they have won.

Colasanto told the council that as an economy move the city school system should close all of its libraries and rely instead on city-run libraries. He said the space used for school libraries could be used for other purposes. The council took no action on his proposal.