The D.C. Department of Human Resources has taken a major step toward compliance with a federal contempt of court order against five city officials - including Mayor Walter E. Washington - by eliminating a backlog of nearly 900 unprocessed welfare applications, the mayor announced yesterday.

Acting DHR director Albert P. Russo was unable to say yesterday how far the agency has progressed towards compliance with three other portions of a Feb. 18 order by U.S. District Court Judge Aubrey E. Robinson.

Russo said he was confident that DHR would be able to satisfy all four requirements by May 2, the date by which the agency has told the judge it will have eliminated the backlog and established assurances that no new backlog will develop.

If DHR is not in full compliance by May 2, the five persons cited could be jailed or fined.In addition to the mayor and Russo, they are former DHR director Joseph P. Yeldell: Bertrell Hallum, DHR administrator of payments assistance: and Oliver Downs, manager of DHR's Congress Heights Services Center.

Robinson found the five in contempt of court after it was disclosed late last year that DHR had just complied with a 1974 order by the judge stipulating that all welfare applications be processed within 45 days. Welfare applicants cannot begin to receive assistance checks until their applications have been processed and their eligibility determined.

Russo said yesterday that 30 caseworkers have worked full-time since mid-February on eliminating the backlog of 899 applications and completed the job early this week.

DHR officials previously had said that a lack of staff was one of the major reasons why the processing backlog had developed. Since October, Russo said, 50 more persons have been added to the applications processing staff, including 20 who have been hired since early January - the time during which Robinson held proceedings that led to the contempt citation.

In addition, Russo said, DHR now has a staff of 74 persons at eight service centers whose sole task is processing the approximately 750 applications the agency receives each month for assistance through the Aid to Families with Dependent Children program.

These 74 also handle applications for payments through the General Public Assistance program (GPA), which provides temporary disability payments to adults, Russo said. Under the new system designed to eliminate backlogs, AFDC and GPA processing is done separately from eligibility determinations for other similar programs, such as medicaid, food stamps and emergency assistance, he said. A person's eligibility for welfare is not delayed that way while his eligibility for other programs is being determined.

The major part of processing welfare applications involves verifying the income claims of the applicant and sometimes it can be a very involved process. Rent receipts often are checked, for example, to verify residency in the District. Birth and school enrollment records also must be examined to determine if the number of dependents claimed is valid.

Recently enacted federal provisions also require that applicants give welfare officals assistance in locating an absent father who may be able to contribute to the support of the children.

Russo said the city currently has about 31,000 AFDC cases providing assistance to 108,000 people - 75 per cent of whom are children.

Amont the three other provisions cited in the court order on which Russo was unable to report were steps being taken by DHR to assure that a new backlog would not develop.

Another provision DHR must meet, Russo said, is that every potential applicant must be allowed to make an AFDC application on the same day the appicont comes to the service center rather, than having to come back a second time to submit an application.

The fourth assurance DHR must make is that all applicants be immediately informed orally and in writing that they have a right to a hearing if they are not hold of their eligibility status within 45 days.

Russo appeared at the press conference with the mayor on the first day since he took over the acting directorship from Yeldell, who temporarily had been reinstated to the position Monday following a 120-day suspension.

"I pledge you my complete commitment to administer your Department of Human Resources," Russo told the mayor in prefacing his remarks. "With that commitment goes my total loyalty to you." Yeldell had been made a general assistant to the mayor.

Russo said 30 of the additional people hired in payments assistance administration are being paid through increased money made available for that purpose last year by Congress. Another 20 persons were hired with grant money from the federal Comprehensive Employment Training Act, which provides temporary jobs in areas of high unemployment.

Russo said funds are available to hire another 54 persons, but not all of those jobs can be filled immediately because of a hiring ceiling imposed by Congress on the D.C. government.