Advanced Water Recovery Technologies

Zero liquid discharge (ZLD) industrial applications currently receive a great deal of attention in the water industry press, but this most advanced level of wastewater treatment and reuse is really just the tip of a bigger iceberg

Certainly for the most water-stressed and water polluted regions of the world, industrial manufacturers and utilities have made strong regulatory pushes for increased ZLD adoption. The China power and coal-to-chemicals sectors are good examples, as are regions of India where all industrial manufacturers with wastewater discharge to river systems have been required to adopt ZLD technology. But high recovery water treatment technologies have many other application spaces and value propositions with high demand in the coming years. These applications are global and local in nature. They occur across multiple geographies and industry segments, but they are tied to specific local water scarcity, economic and legislative characteristics that collectively add up to a large application space for the technologies.

China water scarcity and economic expansion

In China’s industrial wastewater landscape, directives mandating ZLD and water reuse in certain industries and regions and their potential opportunities are exciting and daunting. These market drivers are closely connected to the way in which fresh water resources are distributed naturally across the country relative to where population concentrations and industrial expansion are located, particularly in coal-based industries. A 2013 Brookings Institute brief by Scott Moore lays out the big picture well. “China is blessed with the world’s fifth largest volume of freshwater, but on a per-capita basis it is well below the global average, at 2,000 m3 per person per year vs. 6,200 m3 per person per year. Freshwater resources per capita are highest in the mountainous and less populous southwest and is lowest in the north, where it is more arid and where the largest and fastest growing cities are, such as Beijing and Tianjin. In the north the per-capita average is below 500 m3/person/year.” This water distribution discrepancy has driven a massive central government water plan which has led to water rebalancing and distribution projects such as the famous Three Gorges Dam.

The north of China also contains the country’s coal belt, where the expansion of coal power and coal-to-chemical industries are not only tremendous industrial water users, but are vitally important to China’s economic future and independence from foreign oil. A 2013 World Resources Institute (WRI) report detailed China’s plan to add 363 coal fired power plants to their national fleet, adding more than 550 gigawatts of capacity (75 percent) to the existing 758 gigawatts of coal power. A Bloomberg article based on the WRI report determined that 51 percent of these plants will be in the water-starved north of China, near the largest coal reserves.

This points to why a strong push exists in China for ZLD and high recovery wastewater treatment tied to existing and newly built coal power plants. Coal-to-chemical manufacturing follows the same trends, concentrated in the north-central part of the country, requiring large annual volumes of freshwater., It is also mandated to include ZLD wastewater treatment. Financial Times in 2014 reported on 18 coal-to-chemical projects under construction in China with a total of 54 in the pipeline for possible construction. China’s water treatment design institutes, consultants and technology decision makers for the wastewater process technologies for these projects have sought out best-in-class technologies for reducing the energy consumption and cost of wastewater pretreatment, brine concentration and final crystallization of salts for disposal or resale.

Given these enormous pressures, it is not surprising that they have also been among the early adopters of advanced technologies such as forward osmosis (FO) for high recovery treatment of waste streams such as flue gas desulfurization (FGD) wet scrubber blowdown, boiler feedwater treatment regeneration streams and cooling tower blowdown. Overall, the size, water complexity and sheer number of projects in China present a growth opportunity for advanced wastewater technologies through at least 2020 and are proving to be an exciting, if not challenging, new market for next generation water technologies.

India water pollution mitigation

India is another market where strict industrial water regulation had been implemented to mitigate serious river pollution issues and address water scarcity in many regions of the country. According to GWI research, only 30 percent of wastewater generated in India is treated in any way, including wastewater from municipal, commercial and industrial sources. For the industrial sector, the Indian government has promoted ZLD and near ZLD as wastewater mandates for the largest wastewater generators, which a 2013 International Water Management Institute report identified as the thermal power, steel and petrochemical industries. Transitioning these large water users and wastewater generators toward reuse and ZLD can reduce the consumption of freshwater and the volume of wastewater generated, but it will take time and new solutions.

The southern Indian state of Tamil Nadu is one example of the effective implementation of industrial water reuse and ZLD. In a 2014 case study presented at the International Conference on “Green Enterprises and Green Industrial Parks,” Sajid Hussain, chief operations office of the Tamil Nadu Water Investment Co. presented on the region’s water problems and the adoption of ZLD. The regional regulations, central treatment plant funding and implementation began in the late 2000s and have already impacted nearly 600 processors. One-hundred and fifty of the largest constructed independent plants (typically 50 to 150 m3/day) and the rest either closed or sent wastewater to one of 20 central plants (typically 500 –to1000 m3/day). Problems with these early ZLD plants, due to suboptimal designs, seasonal and process-related water quality fluctuations and other issues, have become legendary in the region. And while enforcement of the regulations was not always thorough in the initial years, this is changing and has created opportunities for companies with ZLD experience and viable advanced water recovery technologies. Also, textile processing and other industries in the region continue to expand and require the capacities of their water recovery plants to grow as well. Advanced organics removal, forward osmosis (FO), other brine concentration and selective salt recovery technologies which can reduce water recovery costs and salt processing costs have the opportunity to prove their performance in Tamil Nadu and expand into the larger industrial wastewater markets in petroleum, power and steel. GWI predicts a doubling of demand in India for industrial wastewater treatment spending, from $1 billion in 2013 to $2 billion in 2020.

Source: Water Technology

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• Technology
• Zero Liquid Discharge
• Water & Wastewater