Edit in JSFiddle

var Conditions = {
    'Number': ['=', '!=', '>', '<'],
    'String': ['Contains', '=', '!='],
    findByType: function (type) {
        for (p in this) {
            if (typeof this[p] === "object" && p == type) {
                return this[p];
            }
        }

        return [];
    }
};

var _columns = [
        { Column: 'DeveloperName', Display: 'Developer', Type: 'String' },
        { Column: 'IssueID', Display: 'Issue ID', Type: 'Number' },                
        { Column: 'IssuetTitle', Display: 'Issue Title', Type: 'String' },
        { Column: 'IssuetDescription', Display: 'Issue Description', Type: 'String' }
    ];
    
function findFilterColumn(column) {
    for (var i = 0; i < _columns.length; i++) {
        if (_columns[i].Column == column) {
            return _columns[i];
        }
    }

    return null;
};

var Filter = function(column, condition, nextFileterBinaryCondition, type, value) {
    this.ColumnObj = ko.observable(findFilterColumn(column || ""));
    this.ColumnObj.subscribe(

    function(value) {
        this.Value(null);
    }, this);
    this.Column = ko.dependentObservable(

    function() {
        return (this.ColumnObj() != null) ? this.ColumnObj().Column : "";
    }, this);

    this.Condition = ko.observable(condition || null);

    this.NextFileterBinaryCondition = ko.observable(nextFileterBinaryCondition || "AND");

    this.Type = ko.dependentObservable(

    function() {
        return (this.ColumnObj() != null) ? this.ColumnObj().Type : null;
    }, this);

    this.AvailableConditions = ko.dependentObservable(

    function() {
        var conditions = Conditions.findByType(this.Type());
        return conditions;
    }, this);

    this.Value = ko.observable(value || "");
};

 function ViewModel (columnsSource) {
    this.nextFileterBinaryConditions = ['AND', 'OR'];
    this.columns = ko.observableArray(columnsSource);
    this.filters = ko.observableArray([new Filter()]);

    this.addFilter = function(filterObj) {        
            var currentIndex = ko.utils.arrayIndexOf(this.filters(), filterObj);
            this.filters.splice(currentIndex + 1, 0, new Filter());        
    };

    this.removeFilter = function(filterObj) {
        this.filters.remove(filterObj);

        if (this.filters().length == 0) {
            this.addFilter();
        }
    };
     
    this.postFilters = function(){        
        var items = ko.toJS(this.filters());
        var mappedItems = ko.utils.arrayMap(items, function(filter) {
            delete filter.ColumnObj;
            delete filter.AvailableConditions;
            
            return filter;
        });
        
        alert(ko.toJSON(mappedItems));
    };
};

ko.applyBindings(new ViewModel(_columns));

<div id="holder">
<ul id="filtersholder" data-bind='foreach: filters'>
    <li>
        <div class="filter-template">
            <input type="button" class="delete-filter" value="-"
                data-bind="click: function() { $root.removeFilter($data); }" />

            <select data-bind="options: $root.columns,                                
                               optionsValue: Column,
                               optionsText: 'Display',
                               value: ColumnObj">
            </select>

            <select class="opperator"
                data-bind="options: AvailableConditions, 
                           value: Condition">
            </select>
            
            <input type="text" data-bind="value: Value" />            

            <select style="width: 54px;" 
                data-bind="options: $root.nextFileterBinaryConditions,
                           value: NextFileterBinaryCondition">
            </select>

            <input type="button" class="add-filter" value="+"
                    data-bind="click: function() { $root.addFilter($data); }" />
        </div>
    </li>
</ul>

<p>
    <input type="button" id="submitFilters"  value="Submit" data-bind="click: postFilters" />
</p>

</div>