**3.4 DRS reverse logistics**

To save the natural environment, the concept and operations of the reverse logistics should be considered and implemented in the disaster relief materials management. The DRS reverse logistics operations deals with a diversity of materials and waste from food surplus to medical surplus, consumable goods to durable goods, end-of-use product to end-of-life product, and packaging waste to debris waste, that exposes itself to the management challenges in the process of reusing (including the maintaining services), repairing, refurbishing, recycling and disposal. Some of the activities must be carried out under difficult situations simultaneously with disaster relief operations (e.g., removing unsolicited donations or debris waste), some of the decisions should take serious consideration of the social and environmental impacts in advance (e.g., resale options for the products with market values). Most importantly, given budget constraints and cost burdens, it lacks incentives, or even impossible for the DRS management and suppliers to operate a wide range of reverse systems simply with moral requirements or enforced regulations. Innovative and cost-effective business models for recapturing value or benefits from closing material loops are much more attractive for both academic research and practical applications [11, 12].

To bring the Right relief supplies with the Right quality and Right quantity at the Right time to the Right sites to serve the Right beneficiaries, called 6R rule in disaster rescue and relief operations [13], is well discussed and implemented in practice. However, a rich body of knowledge documented in commercial inventory management research provides limited insights in disastrous conditions. Comparing with the conventional practice, the DRS reverse logistics has at least several advantages in product value, operational cost, economies of scale in operations management, and management strategical consideration.

The products or parts handled in the conventional reverse logistics are of low value and not directly useful. But, most of the goods stored for disaster rescue and relief purposes are consumable [10]. Take the massively reserved food commodities as an example. The "food waste hierarchy" has been widely discussed in relevant food-management research, which indicates that the reuse option for surplus food, which refers to the removal of food from its intended supply chain, is highly recommended if the removed food is still fit for human consumption. Since the prevention of product depreciation is of top priority, food inventories should be updated and replenished with fresh items periodically before going expired. When removed, DRS managers and their suppliers could have a set of marketing choices. Transferring to legitimate secondary markets with markdown prices or selling with promotions and discounts in the supplier's primary market are both cost-effective options, dependent on the residual value of the food. In addition, donating them to other ongoing humanitarian programs or local food aid services for the poor population could be taken into consideration.

Capital items and rescue and relief equipment are normally kept in a higher level of organization centers, which also provide regular maintenance and normal repairing after operations. Quality guaranteed recovery management of these relief items should be incorporated into the overall planning because it may have a profound impact on the next disaster response operations. There is a chance to develop "sharing economy" markets between the suppliers and the equipment management organizations to seek the pooling of costs and risks, which lies within effective communication of information, proper design of cooperation schemes, and corresponding regulations or insurance to avoid moral hazard, bilaterally. Currently, there is not sufficient attention in either academic or business aspects addressing the recovery management issues of capital items and equipment in the humanitarian context.

The DRS items are in relatively concentrated storage and have about the same conditions. This feature gives the economies of scale in all operations of reverse logistics. The inspection process conducted before the removal can be implemented in the regular standards based on the statistical sampling instead of individual checking done in the conventional reverse logistics. These items can be assigned for reuse or remarketing simply at a lower price. The transportation and logistics in moving these items can be properly pre-arranged since the moving timing, purpose, and destination are all planed previously. The logistics cost is low due to the economies of scale. The operations can achieve high time efficiency for loading, transportation, unloading, refurbishing, remanufacturing, disposal, and others in the batch. This is the largest distinction comparing to the operations in reverse logistics in business supply chain management.

DRS are prepared, organized, and managed mainly by the government or semi-government agencies. This gives much flexibility and large room for DRS reverse logistics operations management. The fundamental purpose of DRS reverse logistics is to recover material value such that the operational cost can be saved and to minimize the waste so that the natural environment can be protected. Unlike the reverse logistics activities led by commercial organizations, the operations strategy of DRS reverse logistics is not restricted by other strategical considerations, such as profit maximization or market cannibalization.
