Bio-inspired wastewater treatment using agricultural wastes

含油废水是世界上许多行业不可避免的副产品，包括石油炼制、金属加工、食品加工、食用油生产、油漆制造和木材保鲜等行业。加拿大是全球最大的食品和木材产品出口国之一，拥有第二大可采油藏，几乎所有可能产生有害含油废水的行业都在加拿大。油砂行业的用水尤其令人担忧。蒸汽辅助重力抽提（SAGD）沥青抽提是将蒸汽注入地下以降低沥青的粘度，促进沥青的抽提。然后，水和沥青的混合物返回到地面，在那里，通过一系列常规的重力、浮选和撇油过程将沥青和水分离，从采出水中去除沥青和剩余油。这些技术不环保，而且处理效率低，投资和维护成本高，产生大量污泥，能耗高。因此，本研究项目的重点是利用天然有机吸附剂开发一种可持续、经济、环保的技术。来自农业副产品的吸附剂由于其作为起始材料的低成本和高可用性而具有特别的优势。这些材料中碳水化合物聚合物的高含量通过碳水化合物聚合物丰富的羟基与水污染物之间的一系列化学反应增加了它们的吸附能力。麦秸是加拿大最容易利用的农业废弃物之一。仅艾伯塔省就生产了560万吨小麦、大麦、燕麦和亚麻秸秆，其中一些秸秆用于土壤保护和牲畜饲养。利用废麦秸作为吸附剂处理含油废水将是一项创新技术，因为该系统的工作原理是“废物处理废物”，即在美国，该系统利用废秸秆处理废水，并从废水中产生处理后的水，同时还有带油的饱和秸秆，这也是一种废物，但由于它是可生物降解的，因此可以很容易地处理。

Oily wastewater is an inevitable byproduct of many industries worldwide including petroleum refining, metalfinishing, food processing, edible oil production, paint manufacturing, and wood preservation industries. Asone of the largest global exporters of food and wood products with the second largest recoverable oilreservoirs, Canada has almost all the industries that can produce hazardous oily wastewater. Water usage in theoil sands industry, in particular, is the biggest concern. In the steam assisted gravity drainage (SAGD) forbitumen extraction steam is injected into the ground to decrease the viscosity of bitumen and to facilitate itsextraction. The mixture of water and bitumen then returns to the surface where the bitumen and water areseparated using a series of conventional gravity, flotation, and oil skimming processes to remove the bitumenand residual oil from the produced water. These techniques are not eco-friendly and suffer from inefficienttreatment, high capital and maintenance cost, generation of large volumes of sludge, and high energyconsumption. Hence, the focus of this research project is to develop a sustainable, cost-efficient andenvironmentally-friendly technique by utilizing natural organic adsorbents.Adsorbents originated from agricultural by-products are particularly advantageous due to their low-cost andhigh availability as starting materials. The high content of carbohydrate polymers in these materials increasestheir adsorption capacity through a series of chemical reactions between abundant hydroxyl groups ofcarbohydrate polymers and water contaminants. Wheat straw is one of the most available agricultural waste inCanada. Alberta alone yields 5.6 Mt of wheat, barley, oat and flax straw even after utilizing some for soilconservation and livestock feeding. Utilization of the waste wheat straw as an adsorbent for the treatment ofoily wastewaters will be an innovative technique since the system works on the principle of 'waste by waste',i.e., the system utilizes waste straw for treating the wastewater from which it generates treated water along withsaturated straw with oil which again is a waste but can be handled easily since it is biodegradable.