Eleven statewide waste characterization studies were compared to assess variation in the quantity and composition of waste after separation of recyclable and compostable materials, i.e., discarded ...waste. These data were also used to assess the impact of varying composition on sequestered carbon and methane yield. Inconsistencies in the designation of waste component categories and definitions were the primary differences between study methodologies; however, sampling methodologies were consistent with recommended protocols. The average municipal solid waste (MSW) discard rate based on the statewide studies was
1.90 kg MSW
person−1
day−1
, which was within the range of two national estimates: 2.35 and
1.46 kg MSW
person−1
day−1
. Dominant components in MSW discards were similar between studies. Organics (food waste, yard trimmings), paper, and plastic components averaged
23.6±4.9%
,
28.5±6.5%
, and
10.6±3.0%
of discarded MSW, respectively. Construction and demolition (C&D) waste was
20.2±9.7%
of total solid waste discards (i.e., MSW plus C&D). Based on average statewide waste composition data, a carbon sequestration factor (CSF) for MSW of 0.13 kg C dry
kg
MSW−1
was calculated. For C&D waste, a CSF of 0.14 kg C dry kg C and D
waste−1
was estimated. Ultimate methane yields
(
Lo
)
of 59.1 and
63.9
m3
CH4
wet Mg
refuse−1
were computed using EPA and state characterization study data, respectively, and were lower than AP-42 guidelines. Recycling, combustion, and other management practices at the local level could significantly impact CSF and
(
Lo
)
estimates, which are sensitive to the relative fraction of organic components in discarded MSW and C&D waste.
We investigate the following family of evolutionary 1+1 PDEs that describes the balance between convection and stretching for small viscosity in the dynamics of one-dimensional nonlinear waves in ...fluids: \ m_t\ +\ \underbrace{\ \ um_x\ \ }_{\text{convection}}\ +\ \underbrace{\ \ b\,u_xm\ \ }_{\text{stretching}}\ =\ \underbrace{\ \ \nu\,m_{xx}\ }_{\text{viscosity}} \quad\text{with}\quad u=g*m. \ Here u=g*m denotes $u(x)=\int_{-\infty}^\infty g(x-y)m(y)\,dy$. This convolution (or filtering) relates velocity u to momentum density m by integration against the kernel g(x). We shall choose g(x) to be an even function so that u and m have the same parity under spatial reflection. When $\nu=0$, this equation is both reversible in time and parity invariant. We shall study the effects of the balance parameter b and the kernel g(x) on the solitary wave structures and investigate their interactions analytically for $\nu=0$ and numerically for small or zero viscosity. This family of equations admits the classic Burgers "ramps and cliffs" solutions, which are stable for -1 < b < 1 with small viscosity. For b < -1, the Burgers ramps and cliffs are unstable. The stable solution for b < -1 moves leftward instead of rightward and tends to a stationary profile. When $m=u-\alpha^2u_{xx}$ and $\nu=0$, this profile is given by $u(x)\simeq{\rm sech}^2(x/(2\alpha))$ for b=-2 and by $u(x)\simeq{\rm sech}(x/\alpha)$ for b=-3. For b > 1, the Burgers ramps and cliffs are again unstable. The stable solitary traveling wave for b > 1 and $\nu=0$ is the "pulson" u(x,t)=cg(x-ct), which restricts to the "peakon" in the special case $g(x)=e^{-|x|/\alpha}$ when $m=u-\alpha^2u_{xx}$. Nonlinear interactions among these pulsons or peakons are governed by the superposition of solutions for b > 1 and $\nu=0$, \ m(x,t)=\sum_{i=1}^N p_i(t)\,\delta(x-q_i(t)),\quad u(x,t)=\sum_{i=1}^N p_i(t)\,g(x-q_i(t)). \ These pulson solutions obey a finite-dimensional dynamical system for the time-dependent speeds pi(t) and positions qi(t). We study the pulson and peakon interactions analytically, and we determine their fate numerically under adding viscosity. Finally, as outlook, we propose an n-dimensional vector version of this evolutionary equation with convection and stretching, namely, \ \frac{\partial }{\partial t}\mathbf{m} \ + \underbrace{\ \mathbf{u}\cdot\nabla \mathbf{m}\ }_{\text{convection}} + \underbrace{\ \nabla \mathbf{u}^T\cdot\mathbf{m} + (b-1)\,\mathbf{m}({\rm div\,}\mathbf{u})\ }_{\text{stretching}} =0 \ for a defining relation, $\mathbf{u}=G*\mathbf{m}$. These solutions show quasi-one-dimensional behavior for n,k=2,1 that we find numerically to be stable forb=2. The corresponding superposed solutions of the vector b-equation in n dimensions exist, with coordinates $\mathbf{x}\in{R^n}$, $s\in{R^k}$, n-k > 0, and 2N parameters $\mathbf{P}_i(s,t),\mathbf{Q}_i(s,t)\in{R^n}$, \mathbf{m}(\mathbf{x},t) &=& \sum_{i=1}^N\int\mathbf{P}_i(s,t)\, \delta\bigl(\,\mathbf{x}-\mathbf{Q}\,_i(s,t)\,\bigr)ds,\quad \mathbf{m}\in{R^n}, \\ \mathbf{u}(\mathbf{x},t) &=& \sum_{i=1}^N\int\mathbf{P}_i(s,t)\, G\bigl(\,\mathbf{x}-\mathbf{Q}\,_i(s,t)\,\bigr)ds,\quad \mathbf{u}\in{R^n}. These are momentum surfaces (or filaments for $k=1$), defined on surfaces (or curves) $\mathbf{x}=\mathbf{Q}\,_i(s,t)$, i=1,2,. . .,N. For b=2, the $\mathbf{P}_i(s,t),\mathbf{Q}_i(s,t)\in{R^n}$ satisfy canonical Hamiltonian equations for geodesic motion on the space of n-vector valued k-surfaces with cometric G.
The decomposition of landfilled refuse proceeds through distinct phases, each defined by varying environmental factors such as volatile fatty acid concentration, pH, and substrate quality. The ...succession of microbial communities in response to these changing conditions was monitored in a laboratory-scale simulated landfill to minimize measurement difficulties experienced at field scale. 16S rRNA gene sequences retrieved at separate stages of decomposition showed significant succession in both
Bacteria
and methanogenic
Archaea
. A majority of
Bacteria
sequences in landfilled refuse belong to members of the phylum Firmicutes, while Proteobacteria levels fluctuated and Bacteroidetes levels increased as decomposition proceeded. Roughly 44% of archaeal sequences retrieved under conditions of low pH and high acetate were strictly hydrogenotrophic (
Methanomicrobiales
,
Methanobacteriales
).
Methanosarcina
was present at all stages of decomposition. Correspondence analysis showed bacterial population shifts were attributed to carboxylic acid concentration and solids hydrolysis, while archaeal populations were affected to a higher degree by pH. T-RFLP analysis showed specific taxonomic groups responded differently and exhibited unique responses during decomposition, suggesting that species composition and abundance within
Bacteria
and
Archaea
are highly dynamic. This study shows landfill microbial demographics are highly variable across both spatial and temporal transects.
Landfills represent a unique microbial ecosystem and play a significant role in global biogeochemical processes. The study of complex ecosystems such as landfills using DNA-based techniques can be ...advantageous since they allow for analysis of uncultured organisms and offer higher resolution in measuring demographic and metabolic (functional) diversity. However, sample acquisition and processing from refuse is challenging due to material heterogeneity. Decomposed refuse was used to evaluate the effect of seven sample processing methods on Bacteria and Archaea community structure using T-RFLP. Bias was assessed using measured richness and by comparing community structure using multi-dimensional scaling (MDS). Generally, direct methods were found to be most biased while indirect methods (i.e., removal of cellular material from the refuse matrix before DNA extraction) were least biased. An indirect method using PO₄ buffer gave consistently high bacterial and archaeal richness and also resulted in 28 and 34% recovery of R. albus and M. formicicum spiked into refuse, respectively. However, the highest recovery of less abundant T-RFs was achieved using multiple processing methods. Results indicate differences in measured T-RF diversity from studies of landfill ecosystems could be caused by methodological (i.e., processing method) variation rather than refuse heterogeneity or true divergence in community structure.
Abstract
Refuse decomposition in landfills is a microbially mediated process that occurs primarily under anaerobic conditions. Because of limited moisture conditions, hydraulic transport as a means ...of cellular translocation within the landfill appears limited, especially during the initial stages of decomposition. Thus, microbial communities within the incoming refuse serve as a primary source of facultative and obligate anaerobic microorganisms that initiate refuse decomposition. Fresh residential refuse was collected five times over 26 months, and microbial communities in these samples were compared with those in individual refuse components and decomposed refuse. Bacterial and archaeal community structures were determined using T-RFLP. The Bacterial microbial community richness was correlated (r2 = 0.91) with seasonal differences in ambient air temperature. Analysis of the results shows that fresh refuse is most likely not the source of methanogens in landfills. Microbial communities in the solid and leachate phases were different, indicating that both matrices must be considered when characterizing microbial diversity within a landfill.
Despite a considerable overlap between people experiencing homelessness and people living with substance use disorder, there is a marked lack of integration between Hawai'i's systems of care for ...these populations. This gap in the current system of care often creates barriers to services for those living at the nexus of homelessness and substance use. This article describes Hawai'i's current homelessness and substance use systems of care, paying particular attention to the intersection between these two systems. With Hawai'i consistently ranking among the highest per capita rates of homelessness in the United States, this article argues that the intersection of homelessness and substance use is a pivotal site of intervention for addressing significant social problems. This article positions the Housing First paradigm as a critical model for bridging gaps and eliminating barriers in service provision through systems integration at the program level. Greater fidelity to the broader harm reduction principles underlying this model will effectively organize and equip programs to successfully address the needs of people experiencing homelessness and struggling with substance use.
Landfill gas contains numerous speciated organic compounds (SOCs) including alkanes, aromatics, chlorinated aliphatic hydrocarbons, alcohols, ketones, terpenes, chlorofluoro compounds, and siloxanes. ...The source, rate and extent of release of these compounds are poorly understood. The objective of this study was to characterize the release of SOCs and the regulated parameter, non-methane organic compounds (NMOCs) during the decomposition of residential refuse and its major biodegrad able components paper (P), yard waste (YW), food waste (FW). Work was conducted under anaerobic conditions in 8-L reactors operated to maximize decomposition. Refuse and YW were also tested under aerobic conditions. NMOC release during anaerobic decomposition of refuse, P, YW, and FW was 0.151, 0.016, 0.038, and 0.221 mg-C dry g-1, respectively, while release during aerobic decomposition of refuse and YW was 0.282 and 0.236 mg-C dry g-1, respectively. The highest NMOC release was measured under abiotic conditions (3.01 mg-C dry g-1), suggesting the importance of gas stripping. NMOC release was faster than CH4 production in all treatments. Terpenes and ketones accounted for 32−96% of SOC release in each treatment, while volatile fatty acids were not a significant contributor. Release in aerobic systems points to the potential importance of composting plants as an emissions source.
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