Zero Waste and Green Buildings
This month's M/E Roundtable focuses on a dirty word-pollution-by asking leading engineers about design strategies and technologies for minimizing air pollution, wastewater and solid waste. Their varied responses focus on building systems but also examine process waste streams, with references to regulatory issues and recent clients and occupancies.
CONSULTING-SPECIFYING ENGINEER (CSE) : What kinds of projects are most concerned with reducing pollution and waste? Which client types or industries seem to be the most innovative or proactive?
KLOPPING : In our experience, the environmental solutions we're providing to our pharmaceutical and microelectronics clients are the most innovative and reflect the high priority these two market sectors place on reducing pollution and waste.
MECKLER : Our most sensitive projects-for which indoor-air quality [IAQ] and waste-disposal issues are critical-involve hospitals, medical offices and clinics, industrial laboratories, manufacturing plants and associated clean-room facilities. Our most proactive clients include hospitals, medical offices and clinics and industrial laboratories, particularly where both effluent streams and airborne contaminants are adjacent to residential communities or where stack dispersal studies suggest carry-over.which could present a threat to human health.
CURATO : One specific example of success that we are very familiar with is water-use reduction within the pulp and paper industry. After implementing initiatives to reduce and reuse, most mills are operating at a fraction of their former water-use rates. However, we find the most significant variable governing a client's sensitivity and emphasis on reducing pollution and waste to be their corporate culture. If a client's leadership philosophy embodies a serious commitment to environmental sustainability, they will demand that life-cycle assessment tools be applied to engineering and design and, more importantly, will succeed in implementing sustainable aspects in their building projects.
Industries that care
Industries that compete globally, especially in the European Union and Asia, have developed environmental management systems (EMS) that comply with international standards, and conduct business accordingly. However, the clients we see succeeding to the greatest extent are those with leadership and the ability to create and communicate their sustainability vision, independent of [standard industrial classification] SIC code or EMS certification status.
CSE : Part of pollution prevention is "source reduction." What sources are affected by good design engineering?
CURATO : Architects and engineers have leveled the playing field in the last 20 years concerning energy-efficient designs. Driven somewhat by code-and now mostly by cost-conscious clients-all firms can develop state-of-the-art energy-efficient designs if requested (see "Life-Cycle Cost Is Key to Zero Waste," page 38).
MECKLER : Source reduction can be most cost-effective and practical in reducing airborne contaminant levels, particularly where direct exhaust of high-concentration effluent is feasible or nonintrusive to operations. Once contaminants of concern become diluted by ambient air-and still remain at harmful concentrations-air filtration or cleaning [or both] can prove expensive and often less effective.
Aside from manufacturing processes, sources of air contaminants with potential health impacts include cleaning chemicals, copy machines, bioeffluents generated by high humidity-e.g., 70-percent relative humidity or above-and conditions within sealed or insufficiently ventilated building space.
KLOPPING : Another common source is floor cleaning. The floor-cleaning chemicals themselves and the contaminants contained therein are problematic with respect to wastewater treatment or disposal. The design of floor sumps, drains and trenches impacts the fate of VOCs [volatile organic compounds] in a waste stream and can significantly contribute to fugitive emissions.
MECKLER : Also of concern are emissions associated with initial occupancy in new buildings where outgassing from new furniture or finishes may be high. Where such possibilities exist, we generally recommend ramping up ventilation rates by artificially lowering thermostat set points during both occupied and nonoccupied hours until acceptable contaminant levels can be maintained by monitoring. We also recommend that occupancies not be undertaken until adequate air balances and/or commissioning is completed.
CSE : With those sources in mind, how can engineers design pollution prevention into today's facilities?
KLOPPING : The use of water-based cleaners and reuse of cleaning chemicals can significantly reduce pollution ... Elimination of single-pass cooling water through the use of cooling towers and closed-loop cooling systems conserves water and minimizes thermal pollution. Design sumps and drains to discourage volatilization or prevent the escape of VOCs.
MECKLER : Methods for prevention of unwanted airborne contaminant carry-over into occupied space in the industrial sector have been established by industrial hygienists. The [American Conference of Governmental Industrial Hygienists] ACGIH design guide already serves as a source for proven strategies. With regard to commercial buildings, utilizing variable-air-volume systems for improved energy efficiency often fails to provide adequate ventilation air at all part-load conditions and, accordingly, IAQ problems may arise. One can utilize a bypass filtration strategy to minimize overventilation, provided proper control of CO 2 and other contaminants of concern are monitored.
CURATO : The answer is not as simple as specifying energy-efficient motors and state-of-the-art lighting systems. If, for example, the site's power grid is dominated by nuclear and natural gas, the extra cost of high-end energy-efficient fixtures may be better spent providing a remote park-and-ride lot with shuttle service to reduce greenhouse-gas emission from employee commuting.
MECKLER : With respect to wastewater and other pollutant streams, design practice is often driven by local ordinances and the U.S Environmental Protection Agency [EPA]. Control technologies vary significantly, particularly where there is contamination of soil and potential downstream exposure to groundwater. Use of selected microorganisms may assist in the remediation of such contaminants.
CSE : What are the most significant new technologies to emerge recently for air, water and other building pollution streams? Where have you seen it used?
KLOPPING : Membrane bioreactors are increasing in popularity due to increased reliability and reduced cost of membrane systems. In certain applications, the use of membranes for solids separation is a significant enhancement over the traditional clarifier and offers higher assurance in pollution prevention, as well as the opportunity for reuse.
Reclamation and remediation
CURATO : Membrane-separation technology is rapidly overcoming its perceived expense. Improved acceptance is driving installed costs down, coupled with the increasing value of its benefits. We believe the value of reclaiming water and raw materials-process chemicals-for reuse and avoiding disposal costs will accelerate membrane-separation technology growth.
MECKLER : Bioremediation versus air stripping and incineration for potentially harmful contaminant spills ... can substantially reduce the time required for remediation and has been used on a selected basis depending upon the nature of the effluent. Essentially, we find anaerobic bacteria strains that feed on such contaminants and consequently cleanse the soil of such impurities without costly removal and replacement of prior contaminated soil.
CURATO : Looking at this issue from another perspective, the proliferation of electrical devices in use over the past decade has had a dramatic effect on power consumption, to the point of negating and even reversing energy conservation progress made in the 1970s and 1980s.
Manufacturing processes aside, the emerging "technology" that is fast becoming most important for preventing pollution is awareness training for the resource user.
CSE : Regulatory and code issues drive many decisions for buildings and processes. Which regulations or codes are the most restricting or onerous?
KLOPPING : Total maximum daily loads, or TMDLs, of pollutants to receiving streams, including point-source and nonpoint-source discharges, are being established based on water-quality standards. TMDLs will have far-reaching consequences for industry. Participation in the TMDL process by all stakeholders, including regulated industries and their communities, is the best way to achieve an equitable waste-load allocation.
Sludge handling and disposal is another increasingly onerous aspect of [designing and operating] most industrial wastewater-treatment facilities.
MECKLER : Regulations or codes may prove onerous for clients when the "best available commercial technology," or BACT, is required for compliance with those laws.
CSE : Which environmental laws and rules are driving the adoption of pollution-prevention practices and technologies?
CURATO : Environmental regulations enacted by many states [for] toxic chemicals, such as Maine's Toxics and Hazardous Waste Reduction law, have resulted in dramatic reductions in emissions of air pollutants and hazardous-waste disposal volumes. It would not be surprising if Maine's recently enacted Mercury Discharge Reduction law results in the statewide elimination of common mercury use.
MECKLER : Sustainable design opportunities can be impacted when the client decides to take advantage of offset emission training where permitted.
CURATO : Environmental laws have caused significant improvement in the quality of our environment. However, the environmental conscience of business and industry leaders will dictate the level of the next plateau.
CSE : Are commercial and industrial buildings-and manufacturing processes-better at preventing pollution today than before?
CURATO : Commercial and industrial buildings and manufacturing processes being built today are far superior in terms of environmental impact than those built 20 years ago. Environmental legislation, codes, and economics have driven this change and will prevent backsliding in the foreseeable future. The economic drivers are probably the most important and include industry's need to improve their competitive position by increasing raw material yield and productivity, thereby reducing waste and associated disposal costs.
MECKLER : Commercial and industrial buildings as well as some manufacturing processes have lowered environmental impacts, particularly where recycling efforts or pretreatment of effluent discharge is employed. In some cases, we have been involved in setting up a pilot operation during the course of remodeling existing manufacturing facilities for clients where effluents are recycled rather than discharged to confirm projected savings.
CSE : What area leaves the most room for improvement?
CURATO : Where we see the greatest potential for further lowering environmental impact is in the environmental conscience of project developers and project end-users. Developers must demand well-planned and researched sustainability features incorporated into their projects by designers, and owners/tenants must operate under sustainability principles in order to achieve minimum environmental impact.
CSE : Still, pollution prevention comes at a cost. Do you try to measure the costs and benefits of such measures?
KLOPPING : Yes, the viability of many pollution-prevention and -control projects rests with our ability to deliver an acceptable return on investment. We are presently in the predesign phase of the largest animal-waste digester in the United States. At first glance this looks like a pollution-control project, but it is actually an energy-production facility. Ultimately, the value of the energy produced by this facility will determine the economic feasibility of this pollution-control alternative.
CURATO : Clients always require cost-benefit analyses. Clients that do not philosophically embrace environmental sustainability will neither fund nor act upon the results of an in-depth analysis of the benefits from seemingly costly variations from traditional designs. So, the methods used to develop indirect benefits-e.g., social benefit, risk avoidance and avoiding future clean-up costs-to offset costly technologies or processes are dictated by each client.
CSE : Are these kinds of projects different outside of the United States? Are we a global leader or laggard in pollution prevention?
CURATO : We feel the United States is a leader in technology development, and neither a leader nor laggard in technology implementation.
MECKLER : Recently we have been involved in evaluating cogeneration projects outside the United States. Where we are aware of a specific [rules] that might exceed U.S. standards but would comply with a lesser national or local standard, we are compelled to point that out to our client, particularly where safety issues and harm to adjacent communities are possible.
U.S. firms are often held to a higher standard when they are aware of such potential problems ... [and] cannot or should hide behind a lesser local or national standard than would be applied under similar conditions here.