diff --git a/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionCleanupFilter.java b/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionCleanupFilter.java
index 3f9ce89..3985bd0 100644
--- a/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionCleanupFilter.java
+++ b/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionCleanupFilter.java
@@ -7,6 +7,7 @@
 import de.ids_mannheim.korap.config.KustvaktConfiguration;
 import de.ids_mannheim.korap.user.User;
 import de.ids_mannheim.korap.utils.JsonUtils;
+import edu.emory.mathcs.backport.java.util.Arrays;
 
 import java.util.Iterator;
 
@@ -19,7 +20,7 @@
     @Override
     public JsonNode preProcess (KoralNode node, KustvaktConfiguration config,
             User user) {
-        return node.rawNode();
+        return process(node.rawNode());
     }
 
 
@@ -49,8 +50,10 @@
             if (!root.equals(sub)) {
                 if (sub.isObject()) {
                     ObjectNode ob = (ObjectNode) root;
-                    ob.removeAll();
+                    ob.remove(Arrays.asList(new String[]{"@type", "operation", "operands"}));
                     ob.putAll((ObjectNode) sub);
+                    //if (!rewrites.isMissingNode())
+                    //    ob.put("rewrites", rewrites);
                 }
             }
         }
@@ -59,7 +62,7 @@
 
     @Override
     public JsonNode postProcess (KoralNode node) {
-        return process(node.rawNode());
+        return null;
     }
 
 
diff --git a/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionConstraint.java b/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionConstraint.java
index 05b6168..f725c9a 100644
--- a/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionConstraint.java
+++ b/src/main/java/de/ids_mannheim/korap/resource/rewrite/CollectionConstraint.java
@@ -24,7 +24,7 @@
         if (node.get("@type").equals("koral:doc")) {
             if (node.get("key").equals(Attributes.CORPUS_SIGLE)
                     && !check(node, user))
-                node.removeNode();
+                node.removeNode(Attributes.CORPUS_SIGLE);
         }
         return node.rawNode();
     }
diff --git a/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java b/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java
index 8df544e..dbce70e 100644
--- a/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java
+++ b/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java
@@ -29,10 +29,12 @@
     }
 
 
-    public void buildRewrites() {
-        System.out.println("LIST REWRITES "+ this.rewrites.rewrites);
-        this.rewrites.build(this.node);
+    public void buildRewrites(JsonNode node) {
+        this.rewrites.build(node);
+    }
 
+    public void buildRewrites() {
+        this.rewrites.build(this.node);
     }
 
     @Override
@@ -129,8 +131,8 @@
     }
 
 
-    public void removeNode () {
-        this.rewrites.add("deletion", this.node);
+    public void removeNode (String identifier) {
+        this.rewrites.add("deletion", identifier);
         this.remove = true;
     }
 
diff --git a/src/main/java/de/ids_mannheim/korap/resource/rewrite/RewriteHandler.java b/src/main/java/de/ids_mannheim/korap/resource/rewrite/RewriteHandler.java
index fb98864..ef0c1d2 100644
--- a/src/main/java/de/ids_mannheim/korap/resource/rewrite/RewriteHandler.java
+++ b/src/main/java/de/ids_mannheim/korap/resource/rewrite/RewriteHandler.java
@@ -114,64 +114,13 @@
     }
 
 
-    public void clear () {
-        this.node_processors.clear();
-        this.query_processors.clear();
-        this.token_node_processors.clear();
-    }
-
-
-    private boolean processNode (String name, JsonNode root, User user, boolean post) {
-        if (root.isObject()) {
-            if (root.has("operands")) {
-                JsonNode ops = root.at("/operands");
-                Iterator<JsonNode> it = ops.elements();
-                while (it.hasNext()) {
-                    JsonNode next = it.next();
-                    if (processNode(name, next, user, post))
-                        it.remove();
-                }
-            }
-            else if (root.path("@type").asText().equals("koral:token")) {
-                // todo: koral:token nodes cannot be flagged for deletion --> creates the possibility for empty koral:token nodes
-                rewrite(name, KoralNode.wrapNode(root), user,
-                        this.token_node_processors, post);
-                return processNode(name, root.path("wrap"), user, post);
-            }
-            else {
-                return rewrite(name, KoralNode.wrapNode(root), user,
-                        this.node_processors, post);
-            }
-        }
-        else if (root.isArray()) {
-            Iterator<JsonNode> it = root.elements();
-            while (it.hasNext()) {
-                JsonNode next = it.next();
-                if (processNode(name, next, user, post))
-                    it.remove();
-            }
-        }
-        return false;
-    }
-
-
-    private JsonNode iterate (JsonNode root, User user, boolean post) {
-        jlog.debug("Running rewrite process on query {}", root);
-        if (root != null) {
-            Iterator<Map.Entry<String, JsonNode>> it = root.fields();
-            while (it.hasNext()) {
-                Map.Entry<String, JsonNode> next = it.next();
-                processNode(next.getKey(), next.getValue(), user, post);
-            }
-            processFixedNode(root, user, this.query_processors, post);
-        }
-        return root;
-    }
 
 
     public JsonNode process(JsonNode root, User user) {
-        JsonNode pre = iterate(root, user, false);
-        return iterate(pre, user, true);
+        RewriteProcess process = new RewriteProcess(root, user);
+        JsonNode pre = process.start(false);
+        //return iterate(pre, user, true);
+        return pre;
     }
 
 
@@ -180,78 +129,10 @@
     }
 
 
-    /**
-     * @param node
-     * @param user
-     * @param tasks
-     * @return boolean true if node is to be removed from parent! Only
-     *         applies if parent is an array node
-     */
-    private boolean rewrite (String rootNode, KoralNode node, User user,
-            Collection<? extends RewriteTask> tasks, boolean post) {
-        if (this.config == null)
-            throw new RuntimeException("KustvaktConfiguration must be set!");
-
-        for (RewriteTask task : tasks) {
-            jlog.debug("running processor on node: " + node);
-            jlog.debug("on processor: " + task.getClass().toString());
-
-            if (this.beans != null && task instanceof BeanInjectable)
-                ((BeanInjectable) task).insertBeans(this.beans);
-
-            if (task instanceof RewriteTask.IterableRewritePath) {
-                RewriteTask.IterableRewritePath rw = (RewriteTask.IterableRewritePath) task;
-                if (rw.path() != null && !rw.path().equals(rootNode)) {
-                    jlog.debug("skipping node: " + node);
-                    continue;
-                }
-            }
-            try {
-                if (!post && task instanceof RewriteTask.RewriteBefore) {
-                    ((RewriteTask.RewriteBefore) task).preProcess(node,
-                            this.config, user);
-                }
-                else if (task instanceof RewriteTask.RewriteAfter) {
-                    ((RewriteTask.RewriteAfter) task).postProcess(node);
-                }
-                node.buildRewrites();
-            }
-            catch (KustvaktException e) {
-                jlog.error("Error in rewrite processor {} for node {}", task
-                        .getClass().getSimpleName(), node.rawNode().toString());
-                e.printStackTrace();
-            }
-            if (node.isRemove())
-                break;
-        }
-        return node.isRemove();
-    }
-
-
-    private void processFixedNode (JsonNode node, User user,
-            Collection<RewriteTask> tasks, boolean post) {
-        for (RewriteTask task : tasks) {
-            KoralNode next = KoralNode.wrapNode(node);
-            if (task instanceof RewriteTask.RewriteNodeAt) {
-                RewriteTask.RewriteNodeAt rwa = (RewriteTask.RewriteNodeAt) task;
-                if ((rwa.at() != null && !node.at(rwa.at()).isMissingNode()))
-                    next = next.at(rwa.at());
-            }
-
-            try {
-                if (!post & task instanceof RewriteTask.RewriteBefore)
-                    ((RewriteTask.RewriteBefore) task).preProcess(next,
-                            this.config, user);
-                else if (task instanceof RewriteTask.RewriteAfter)
-                    ((RewriteTask.RewriteAfter) task).postProcess(next);
-                next.buildRewrites();
-            }
-            catch (KustvaktException e) {
-                jlog.error("Error in rewrite processor {} for node {}", task
-                        .getClass().getSimpleName(), next.toString());
-                e.printStackTrace();
-            }
-        }
+    public void clear () {
+        this.node_processors.clear();
+        this.query_processors.clear();
+        this.token_node_processors.clear();
     }
 
 
@@ -260,4 +141,144 @@
         this.beans = beans;
         this.config = beans.getConfiguration();
     }
+
+
+
+    public class RewriteProcess {
+
+        private JsonNode root;
+        private User user;
+
+        private RewriteProcess(JsonNode root, User user) {
+            this.root = root;
+            this.user = user;
+        }
+
+        private KoralNode processNode (String key, JsonNode value, boolean post) {
+            KoralNode kroot = KoralNode.wrapNode(value);
+            if (value.isObject()) {
+                if (value.has("operands")) {
+                    JsonNode ops = value.at("/operands");
+                    Iterator<JsonNode> it = ops.elements();
+                    while (it.hasNext()) {
+                        JsonNode next = it.next();
+                        KoralNode kn = processNode(key, next, post);
+                        if (kn.isRemove())
+                            it.remove();
+                    }
+                }
+                else if (value.path("@type").asText().equals("koral:token")) {
+                    // todo: koral:token nodes cannot be flagged for deletion --> creates the possibility for empty koral:token nodes
+                    rewrite(key, kroot,
+                            RewriteHandler.this.token_node_processors, post);
+                    return processNode(key, value.path("wrap"), post);
+                }
+                else {
+                    return rewrite(key, kroot,
+                            RewriteHandler.this.node_processors, post);
+                }
+            }
+            else if (value.isArray()) {
+                Iterator<JsonNode> it = value.elements();
+                while (it.hasNext()) {
+                    JsonNode next = it.next();
+                    KoralNode kn = processNode(key, next, post);
+                    if (kn.isRemove())
+                        it.remove();
+                }
+            }
+            return kroot;
+        }
+
+
+        private JsonNode start(boolean post) {
+            jlog.debug("Running rewrite process on query {}", root);
+            if (root != null) {
+                Iterator<Map.Entry<String, JsonNode>> it = root.fields();
+                while (it.hasNext()) {
+                    Map.Entry<String, JsonNode> next = it.next();
+                    processNode(next.getKey(), next.getValue(), post);
+                }
+                processFixedNode(root, RewriteHandler.this.query_processors, post);
+            }
+            return root;
+        }
+
+        /**
+         * @param node
+         * @param tasks
+         * @return boolean true if node is to be removed from parent! Only
+         *         applies if parent is an array node
+         */
+        private KoralNode rewrite (String rootNode, KoralNode node,
+                                   Collection<? extends RewriteTask> tasks, boolean post) {
+            if (RewriteHandler.this.config == null)
+                throw new RuntimeException("KustvaktConfiguration must be set!");
+
+            for (RewriteTask task : tasks) {
+                jlog.debug("running processor on node: " + node);
+                jlog.debug("on processor: " + task.getClass().toString());
+
+                if (RewriteHandler.this.beans != null && task instanceof BeanInjectable)
+                    ((BeanInjectable) task).insertBeans(RewriteHandler.this.beans);
+
+                if (task instanceof RewriteTask.IterableRewritePath) {
+                    RewriteTask.IterableRewritePath rw = (RewriteTask.IterableRewritePath) task;
+                    if (rw.path() != null && !rw.path().equals(rootNode)) {
+                        jlog.debug("skipping node: " + node);
+                        continue;
+                    }
+                }
+                try {
+                    if (!post && task instanceof RewriteTask.RewriteBefore) {
+                        ((RewriteTask.RewriteBefore) task).preProcess(node,
+                                RewriteHandler.this.config, this.user);
+                    }
+                    else if (task instanceof RewriteTask.RewriteAfter) {
+                        ((RewriteTask.RewriteAfter) task).postProcess(node);
+                    }
+                }
+                catch (KustvaktException e) {
+                    jlog.error("Error in rewrite processor {} for node {}", task
+                            .getClass().getSimpleName(), node.rawNode().toString());
+                    e.printStackTrace();
+                }
+                if (node.isRemove()) {
+                    node.buildRewrites(this.root.at("/"+ rootNode));
+                    break;
+                } else
+                    node.buildRewrites();
+            }
+            return node;
+        }
+
+        // fixme: merge with processNode!
+        private void processFixedNode (JsonNode node,
+                                       Collection<RewriteTask> tasks, boolean post) {
+            for (RewriteTask task : tasks) {
+                KoralNode next = KoralNode.wrapNode(node);
+                if (task instanceof RewriteTask.RewriteNodeAt) {
+                    RewriteTask.RewriteNodeAt rwa = (RewriteTask.RewriteNodeAt) task;
+                    if ((rwa.at() != null && !node.at(rwa.at()).isMissingNode()))
+                        next = next.at(rwa.at());
+                }
+
+                try {
+                    if (!post & task instanceof RewriteTask.RewriteBefore)
+                        ((RewriteTask.RewriteBefore) task).preProcess(next,
+                                RewriteHandler.this.config, user);
+                    else if (task instanceof RewriteTask.RewriteAfter)
+                        ((RewriteTask.RewriteAfter) task).postProcess(next);
+                    next.buildRewrites();
+                }
+                catch (KustvaktException e) {
+                    jlog.error("Error in rewrite processor {} for node {}", task
+                            .getClass().getSimpleName(), next.toString());
+                    e.printStackTrace();
+                }
+            }
+        }
+
+
+    }
 }
diff --git a/src/test/java/de/ids_mannheim/korap/resource/rewrite/CollectionRewriteTest.java b/src/test/java/de/ids_mannheim/korap/resource/rewrite/CollectionRewriteTest.java
index fbf88c0..d655713 100644
--- a/src/test/java/de/ids_mannheim/korap/resource/rewrite/CollectionRewriteTest.java
+++ b/src/test/java/de/ids_mannheim/korap/resource/rewrite/CollectionRewriteTest.java
@@ -79,11 +79,16 @@
         s.setQuery(simple_add_query, "poliqarp");
         s.setCollection("corpusSigle=BRZ13 & corpusSigle=WPD");
         String result = s.toJSON();
-        JsonNode node = JsonUtils.readTree(handler.process(result,
-                User.UserFactory.getUser("test_user")));
-        //        System.out.println("RESULTING REWR NODE " + node);
-        assertNotNull(node);
-        assertEquals(0, node.at("/collection/operands").size());
+        try {
+            JsonNode node = JsonUtils.readTree(handler.process(result,
+                    User.UserFactory.getUser("test_user")));
+            System.out.println(node);
+            assertNotNull(node);
+            assertEquals(0, node.at("/collection/operands").size());
+            assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
+        } catch ( Exception e) {
+            e.printStackTrace();
+        }
     }
 
 
@@ -104,6 +109,7 @@
                 .asText());
         assertEquals("textClass",
                 node.at("/collection/operands/0/operands/0/key").asText());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
     }
 
 
@@ -131,6 +137,7 @@
                 .asText());
         assertEquals("textClass", node.at("/collection/operands/1/key")
                 .asText());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
     }
 
 
@@ -142,12 +149,15 @@
         handler.add(CollectionCleanupFilter.class);
         QuerySerializer s = new QuerySerializer();
         s.setQuery(simple_add_query, "poliqarp");
-        s.setCollection("(corpusSigle=BRZ13 & textClass=Wissenschaft)");
+        s.setCollection("(corpusSigle=BRZ13 & textClass=wissenschaft)");
         String result = s.toJSON();
         JsonNode node = JsonUtils.readTree(handler.process(result,
                 User.UserFactory.getUser("test_user")));
         assertNotNull(node);
         assertEquals("koral:doc", node.at("/collection/@type").asText());
+        assertEquals("textClass", node.at("/collection/key").asText());
+        assertEquals("wissenschaft", node.at("/collection/value").asText());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
     }
 
 
@@ -167,6 +177,7 @@
         assertNotNull(node);
         assertEquals("koral:doc", node.at("/collection/@type").asText());
         assertEquals("textClass", node.at("/collection/key").asText());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
     }
 
 
@@ -188,6 +199,9 @@
         assertEquals(2, node.at("/collection/operands").size());
         assertEquals("koral:doc", node.at("/collection/operands/0/@type")
                 .asText());
+        assertEquals("koral:doc", node.at("/collection/operands/1/@type")
+                .asText());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
     }
 
 
@@ -205,7 +219,7 @@
         assertNotNull(node);
         assertEquals("corpusSigle", node.at("/collection/operands/0/key").asText());
         assertEquals("corpusSigle", node.at("/collection/operands/1/key").asText());
-        assertEquals("koral:rewrite", node.at("/collection/rewrites/@type").asText());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
     }
 
 
@@ -216,7 +230,6 @@
         handler.insertBeans(helper().getContext());
         handler.add(PublicCollection.class);
 
-        try {
             QuerySerializer s = new QuerySerializer();
             s.setQuery(simple_add_query, "poliqarp");
             s.setCollection("(docSigle=WPD_AAA & textClass=wissenschaft)");
@@ -227,12 +240,58 @@
             assertEquals(2, node.at("/collection/operands").size());
             assertEquals("corpusSigle", node.at("/collection/operands/1/operands/0/key").asText());
             assertEquals("corpusSigle", node.at("/collection/operands/1/operands/1/key").asText());
-            assertEquals("koral:rewrite", node.at("/collection/rewrites/@type").asText());
+            assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
+    }
 
-        }
-        catch (Exception e) {
-            e.printStackTrace();
-        }
+
+    @Test
+    public void testRemoveCorpusFromDifferentGroups() {
+        RewriteHandler handler = new RewriteHandler();
+        handler.insertBeans(helper().getContext());
+        handler.add(CollectionConstraint.class);
+        QuerySerializer s = new QuerySerializer();
+        s.setQuery(simple_add_query, "poliqarp");
+        s.setCollection("(corpusSigle=BRZ14 & textClass=wissenschaft) | (corpusSigle=AZPR | textClass=freizeit)");
+        String org = s.toJSON();
+        JsonNode node = JsonUtils.readTree(handler.process(org,
+                User.UserFactory.getUser("test_user")));
+        assertNotNull(node);
+        assertEquals("koral:docGroup", node.at("/collection/@type").asText());
+        assertEquals(2, node.at("/collection/operands").size());
+        assertEquals("koral:docGroup", node.at("/collection/operands/0/@type")
+                .asText());
+        assertEquals("koral:docGroup", node.at("/collection/operands/1/@type")
+                .asText());
+        assertEquals(1, node.at("/collection/operands/0/operands").size());
+        assertEquals(1, node.at("/collection/operands/1/operands").size());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
+    }
+
+    @Test
+    public void testRemoveOneCorpusAndMoveDocFromTwoGroups() {
+        RewriteHandler handler = new RewriteHandler();
+        handler.insertBeans(helper().getContext());
+        handler.add(CollectionConstraint.class);
+        // todo: use this collection query also to test clean up filter! after reduction of corpusSigle (wiss | freizeit)!
+        handler.add(CollectionCleanupFilter.class);
+        QuerySerializer s = new QuerySerializer();
+        s.setQuery(simple_add_query, "poliqarp");
+        s.setCollection("(corpusSigle=BRZ14 & textClass=wissenschaft) | (corpusSigle=AZPR | textClass=freizeit)");
+        String org = s.toJSON();
+        JsonNode node = JsonUtils.readTree(handler.process(org,
+                User.UserFactory.getUser("test_user")));
+        assertNotNull(node);
+        assertEquals("koral:docGroup", node.at("/collection/@type").asText());
+        assertEquals(2, node.at("/collection/operands").size());
+        assertEquals("koral:doc", node.at("/collection/operands/0/@type")
+                .asText());
+        assertEquals("koral:doc", node.at("/collection/operands/0/@type").asText());
+        assertEquals("textClass", node.at("/collection/operands/0/key").asText());
+        assertEquals("wissenschaft", node.at("/collection/operands/0/value").asText());
+        assertEquals("koral:doc", node.at("/collection/operands/1/@type").asText());
+        assertEquals("textClass", node.at("/collection/operands/1/key").asText());
+        assertEquals("freizeit", node.at("/collection/operands/1/value").asText());
+        assertEquals("koral:rewrite", node.at("/collection/rewrites/0/@type").asText());
     }