Bio-inspired wastewater treatment using agricultural wastes

含油废水是世界各地炼油、金属加工、食品加工、食用油生产、油漆制造和木材防腐等行业不可避免的副产品。作为全球最大的食品和木制品出口国之一，加拿大拥有第二大可采油层，几乎拥有所有可以产生危险含油废水的行业。尤其是油砂行业的用水量是最大的担忧。在蒸汽辅助重力排水(SAGD)中，将蒸汽注入地面，以降低沥青的粘度，方便其提取。水和沥青的混合物然后返回到表面，在那里沥青和水通过一系列传统的重力、浮选和撇油过程从产出的水中去除沥青和残油。这些技术不环保，存在处理效率低、资金和维护成本高、产生大量污泥和高能耗等问题。因此，本研究的重点是利用天然有机吸附剂开发一种可持续、低成本、环境友好的技术，其中以农副产品为原料的吸附剂以其低成本和高可获得性而具有特别的优势。这些材料中高含量的碳水化合物聚合物通过碳水化合物聚合物中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。小麦秸秆是加拿大最可利用的农业废弃物之一。仅艾伯塔省就生产了5.6吨小麦、大麦、燕麦和亚麻秸秆，即使在利用其中一些用于土壤保护和牲畜饲养后也是如此。利用废麦秆作为吸附剂处理含油废水将是一项创新的技术，因为该系统的工作原理是以废代废，即该系统利用废秸秆处理废水，从中产生处理后的水，以及含油的饱和秸秆，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.