diff --git a/src/modules/project/services/project.service.js b/src/modules/project/services/project.service.js
index f49bed2..ac987d9 100644
--- a/src/modules/project/services/project.service.js
+++ b/src/modules/project/services/project.service.js
@@ -534,10 +534,10 @@ class ProjectService {
       const { id_project, id_user } = payload;
 
       if (!id_project || !id_user) {
-        return error(new BadRequestError("Project ID and User ID are required"));
+        return error(new BadRequestError("Project ID/slug and User ID are required"));
       }
 
-      const project = await projectRepository.findById(id_project);
+      const project = await projectRepository.findByIdOrSlug(id_project);
       if (!project) {
         return error(new NotFoundError("Project not found"));
       }
@@ -556,7 +556,7 @@ class ProjectService {
       const activeMemberships = await projectRepository.findActiveMembershipsByUserIds([id_user]);
       if (activeMemberships.length > 0) {
         const activeProj = activeMemberships[0].project;
-        if (activeMemberships[0].id_project === parseInt(id_project)) {
+        if (activeMemberships[0].id_project === project.id) {
           return error(new ConflictError("User is already an active member of this project"));
         } else {
           return error(
@@ -567,7 +567,7 @@ class ProjectService {
         }
       }
 
-      const existingMembership = await projectRepository.findMembership(id_project, id_user);
+      const existingMembership = await projectRepository.findMembership(project.id, id_user);
 
       let membership;
       if (existingMembership) {
@@ -603,10 +603,10 @@ class ProjectService {
       const { id_project, id_user } = payload;
 
       if (!id_project || !id_user) {
-        return error(new BadRequestError("Project ID and User ID are required"));
+        return error(new BadRequestError("Project ID/slug and User ID are required"));
       }
 
-      const project = await projectRepository.findById(id_project);
+      const project = await projectRepository.findByIdOrSlug(id_project);
       if (!project) {
         return error(new NotFoundError("Project not found"));
       }
@@ -616,7 +616,13 @@ class ProjectService {
         return error(new NotFoundError("User not found or inactive"));
       }
 
-      const existingMembership = await projectRepository.findMembership(id_project, id_user);
+      if (user.role !== "intern") {
+        return error(
+          new ForbiddenError("Access denied: only interns can be removed from projects")
+        );
+      }
+
+      const existingMembership = await projectRepository.findMembership(project.id, id_user);
 
       if (!existingMembership || existingMembership.status !== 'active') {
         return error(new BadRequestError("User is not an active member of this project"));
diff --git a/src/routes/project.routes.js b/src/routes/project.routes.js
index 4146f0a..459a47c 100644
--- a/src/routes/project.routes.js
+++ b/src/routes/project.routes.js
@@ -825,8 +825,15 @@ router.get('/interns', verifyJWT, isMentorOrAdmin, projectController.getInterns)
  *               - id_user
  *             properties:
  *               id_project:
- *                 type: integer
- *                 example: 1
+ *                 oneOf:
+ *                   - type: integer
+ *                     example: 1
+ *                     description: Project ID
+ *                   - type: string
+ *                     example: internify-lms
+ *                     description: Project slug
+ *                 description: Project ID or project slug
+ *                 example: internify-platform-dev
  *               id_user:
  *                 type: integer
  *                 example: 2
@@ -872,8 +879,15 @@ router.post('/assign-member', verifyJWT, isMentorOrAdmin, projectController.assi
  *               - id_user
  *             properties:
  *               id_project:
- *                 type: integer
- *                 example: 1
+ *                 oneOf:
+ *                   - type: integer
+ *                     example: 1
+ *                     description: Project ID
+ *                   - type: string
+ *                     example: internify-lms
+ *                     description: Project slug
+ *                 description: Project ID or slug
+ *                 example: internify-lms
  *               id_user:
  *                 type: integer
  *                 example: 2